www.paternitytests.info
Posted on | September 24, 2009 | No Comments
DNA Paternity Testing is now the most widely used tool for confirming direct biological relationships. This blog has been set-up to provide in-depth information on the various aspects of the paternity test. If you are planning to order a paternity test or want to know about paternity testing, we recommend that you search through the various DNA paternity testing articles available. Feel free to leave us your comments or feedback!
Unreliable DNA Evidence in Knox-sollecito trial
Posted on | December 13, 2009 | 1 Comment
The Meredith Kercher trial comes to an end as the sentences are finally read for the accused- Amdna Knox and her Italian lover Raffaele Sollecito in the city of Perugia, Northern Italy. However, the defense still questions the reliability of the DNA forensic evidence brought forward by the prosecution and Knox is supported by many who feel she has been unfairly convicted and butchered by the media.
Amanda Knox, sentenced to 26 years in prison, still declares herself Kercher’s friend, claiming that she would have never hurt her. Raffaele Sollecito, Knox’s boyfriend, was sentenced to 27 years. The two have already spent two years behind bars whilst awaiting their final verdict.
The Italian judiciary system has gone under virulent criticism by factions which support Knox’s innocence and mock the flaws of Italian law. Knox’s family have voiced serious doubts about the way the system operates in Italy and champion Amanda’s innocence. Whatever the case, there will unlikely be any diplomatic clashes over the Kercher case between the US and Italy. Knox and Sollecito will have another appeal without jury followed by a final appeal should they lose the second.
Amanda Knox as Devil
The image created by the media of the American student, Amanda Knox, is of one who was often high on drugs, had divergent sexual habit and was a party girl. She has been portrayed as being the instigator of the sex game in which Kercher unwillingly participated. The Italian media have used dehumanizing terms and have undertook a character defamation and Knox using terms which in America might well have been banned from use in the media under such circumstances.
The Flawed DNA Forensic Investigation
A view still upheld by the defense is that the gathering of DNA samples from the crime scene was flawed. This is an issue that has over-spilled into much of the US where sentiment has built up for Knox and her conviction has caused much outrage. The Italian judiciary system has come under attack by many Americans but many also feel that this is the time for Italy to take proper hold of justice and show that it can punish serious crimes with due punishment.
The evidence was pinned onto the questionable murder weapon which was found in Sollecito’s apartment. The knife had Knox’s DNA on the handle and a very small amount of Kercher’s DNA on the blade. However, the defense notes how the knife was unlikely to have been the one that caused the death of Kercher as the wounds in her neck did not match the size of the blade on the supposed murder weapon.
Furthermore, the defense notes how the traces of blood found on the knife proved to yield too little genetic material to produce conclusive DNA results. In fact, they even claim that the forensic DNA evidence was destroyed whilst being analyzed by the forensic DNA experts.
All innocent?
Rudy Hermann Guede was accused by Knox and Sollecito’s lawyers of acting alone in the murder of Kercher. However, he too claims to be innocent and is appealing the case. Sollecito claimed to have received a call in his flat at 11:00pm but this call was never traced. Knox at first claimed to have been in the flat with Kercher and have witnessed Kercher scream as she was being killed; later she claimed she was not actually in the house with Kercher the night she was murdered and only said she was because she was placed under pressure by the police forces of Perugia.
The case will still cause outrage as campaigns have been launched in Knox’s home town of Washington; people will forever sustain the unreliability of the forensic DNA evidence gathered and put forward as court evidence and criticize the judiciary inconsistencies, if any, of the Italian law.
Tags: DNA contamination > DNA evidence > dna testing > dna testing laboratory > forensic DNA test
Genealogy and Ancestry Testing
Posted on | November 25, 2009 | No Comments
Advances in DNA testing have made it possible to accurately carry out DNA ancestry tests to track our ancestral origins. In the past, mapping ancestry relied on searches in archives, birth certificates, death certificates and the likes. Whilst this is still used, internet searches have made things all the easier as such investigation can span a global scale. But ultimately, genetic testing is the most reliable means of determining whether individuals are truly genetically related.
Ancestry Testing for the Romanovs – the last of the Russian Imperial Family
The story of the last Romanovs is a chilling account of the massacre of a whole family and the end of Russian Imperialism. A bit of genealogy is mandatory at this point. Empress Alexandra was Queen Victoria’s granddaughter. She was consort princess to Tsar Nicholas II and the last tsaritsa Russia would see. During the First World War there was a build-up of resentment because the Romanovs had German consorts and a lot of this resentment was channeled in the form of hatred towards Empress Alexandra.
Tsar Nicholas and his family were all shot in July 1918; Nicholas, his wife Alexandra, his four daughters and their son. It was not until 1991 that nine skeletons were found and suspected to be those of the Romanov family. The remains could only be identified correctly using DNA testing techniques which confirmed that the remains in fact where somewhere connected to the Imperial family.
Mitochondrial DNA Testing for the Female Remains
MtDNA testing (mitochondrial DNA testing) was used to identify that the putative tsarina in the grave was the mother of the three other female skeletons found there buried. The DNA forensic testing was complex, before prior to the MtDNA test, all skeletons found in the grave had to undergo the amelogenin gene test to help understand which remains belonged to males and which to females.
MtDNA or mitochondrial DNA is passed only down the female line down the maternal line, from mother to daughter. To further corroborate and confirm findings, scientists involved in the case had to find a living descendent to the Russian imperial family, or better a direct descendent of Empress Alexandra. For this, the investigators turned to the British Royal family. Queen Victoria was Empress Alexandra’s maternal grandmother. Queen Victoria’s DNA type was traced down the family line until her present descendants, namely Prince Philip. By collecting DNA samples from living descendants, genetic profiles could be drawn up and compared to the DNA profiles of the remains found in the grave. STR testing was then used to determine if the remains in the grave were all somehow related to each other. This type of test is very important in forensic DNA testing to locate repeated sequences of DNA which can then be located on the profiles of other relatives.
Ancestry Testing- what is it?
An ancestry test might not require the same depth of research as it did to confirm the remains of the Romanovs. DNA testing companies offer an ancestry test with a wider scope taking populations and native areas into consideration. In-depth research to map whole family trees back generations would prove immensely costly and take months if not years of research. Many DNA testing companies now offer ancestry testing which can be done at home using a simple mouth swab. The scope of this test is far more general. The test will tell you a lot about your ancestral origins, linking you to different anthropological regions and populations and plotting them onto a high resolution map to show your unique geogenetic links. The test will work at locating regional affiliations with the anthropological regions in its database.
DNA testing companies will have access to a DNA database in which are stored the genetic information of thousands of people. The DNA profile of the person who wishes to have their DNA tested for ancestry is compared to those in the database to track their ancestral origins.
What the Test does not do
The results can be fascinating to say the least. You can be ethnically and anthropologically linked to your ancestors and will likely be surprised at who they where and where they came from. However, whilst DNA ancestry testing can establish that you are related to an ethnics group or population, it cannot tell you what exactly the relationship is. Moreover, this type of testing will not establish direct relationships unless the other person undergoes a DNA test. And finally, it will not provide you with your family tree since the exact relationships between individual cannot be determined through this type of test. However, considering the ease and cost friendliness of ancestry testing as opposed to extremely expensive in-depth genealogical research, DNA ancestry testing is indeed an interesting and informative test for anyone wishing to locate ancestral origins.
The Myths Of Paternity Testing
Posted on | October 30, 2009 | No Comments
Today paternity DNA testing has become that most reliable and accurate means of determining biological relationships between an alleged father and a child. Given its widespread use it is normal that there should be a number of myths surrounding this type of testing. Hereunder, I shall try and clarify a few of the most common ones.
I need to have blood taken and this is painful
The days of blood DNA tests are somewhat over and are though still sometimes used, it is rather rare. However, since we are talking about blood, one has to clarify that the process is not painful in itself, but it is invasive, it involves a needle penetrating the skin, bruising which can look unsightly and psychological mini-traumas especially in children. Advances in DNA technology means that today there is the harmless and painless buccal swab. A cotton bud like utensil that is rubbed on the inner cheeks and send to be analyzed in the correct laboratories. Paternity DNA tests cannot be easier with the use of oral swabs and are equally accurate as a blood DNA test.
It is not possible to do DNA testing on an unborn child
Though this is possible it is a rather thorny issue. The procedure is invasive and involves taking cell samples from inside the mother’s womb. Cells are normally gather form either the placenta, the organ which gives the child food and oxygen, or from loose fetal cells. Any samples gathered have to be analyzed very quickly as samples cannot be kept for long. The procedure has a small risk factor- the child can be harmed. Though the risk is small, it is there. Some DNA testing companies have offered this service in the past but chose to do away with it for the above reasons and moreover, for reasons of ethicality. Parents might choose to abort the child should the results not favor their expectations. One should be heavily critical of companies offering pre-natal DNA testing using techniques which are non-invasive as these are not scientifically or medically grounded.
What about confidentiality?
These tests are as confidential as you want them to be. When you buy a home DNA kit you are responsible for taking the samples and returning them to be processed in laboratories. When results are returned determined paternity, they are returned specifically to the address the buyer stipulated. After that, what the buyer of the kit does with the results is up to them. Companies providing DNA testing services guarantee total confidentiality as they understand how delicate and stressful a matter this can be. However, when doing a legal paternity test, one must bear in mind that these will have to appear in court and handed through perhaps, various legal entities. The issue of confidentiality is diminished in such cases.
The lengthy wait for results must be nerve-wrecking
Once the samples of the swabs with the DNA are sent back, it is only a matter of days till they are returned with the results. Of course, there are issues of postage involved but usually the differences here are negligible. Once the swabs are returned with the DNA samples, the results can be expected within 5 to 7 days. Receiving the kit in the first place is another issue. The time here depends on the efficiency of postal services which vary from country to country, whether one opts for courier mail, any strikes there might be.
If there is not father then there can be no paternity DNA test
In the case of an absent, deceased or unwilling father, other members of the alleged father’s family can be tested using what is known as avuncular DNA testing, a substitute test for the standard DNA paternity test. The genetic profiles of the aunt, uncle or grandparent can be used and compared with that of the alleged father’s child. If both the father’s parents are tested, it is possible to re-create the alleged father’s genetic profile and this taken for comparison with the child’s DNA.
Tags: dna paternity > dna paternity test > dna testing > legal paternity test > paternity test kit
DNA testing for twins
Posted on | October 14, 2009 | No Comments
Establishing twins as being either identical or fraternal can accurately be done by means of a Twins DNA test. Whist reliance on facial similarity to make the distinction between the two types of twins is common; this is often misleading and medically discouraged. Identifying the DNA profile of the twins and consequently, comparing genetic blue prints through DNA testing is the principle method advocated by those in the medical field.
What does the DNA Zygosity Twin test tell us?
The zygosity test basically tells us whether the twins in question are monozygotic (identical twins) or dizygotic (fraternal twins). Zygosity is a generic term which encompasses both types of twins and essentially simply refers to the degree of similarity between the twin genomes. Whilst DNA profiles in dizygotic twins (Fraternal twins) can approximate each other, the match between the two twin profiles can however, never be identical. Thus, it is only monozygotic twins (identical twins) that will have identical DNA profiles.
Identical or fraternal – how are they made?
The scientific terms themselves-monozygotic and dizygotic- explain the nature of fertilisation in the two types of twins as it happens at conception. Monozygotic twins are born when one sperm cell (hence, the prefix mono), fertilises one egg and the egg then splits to form two independent embryos. On the other hand, dizygotic twins are formed when two sperm cells (Hence the prefix di) fertilize two separate eggs and both are simultaneously implanted in the uterine wall.
Why perform a Twin DNA Zygosity Test?
The Twin Zygosity DNA test is often done simply out of curiosity as either parents of twins, or twins themselves may have their interest piqued and wish to find out if they are identical or not . However, more importantly, in the case of the need for organ transplants, identical twins offer the highest success rate, reducing dramatically the chance of the organ being rejected. This is due to the identical genetic make up and tissues type of identical twins. The same applies to blood transfusion- identical twins have the same blood group, and thus, should the need arise, one becomes the life line of the other.
Twin Zygosity DNA test and Paternity DNA test
When a paternity test is requested to verify paternal lineage, it is customary to ask for both twins to be sent for testing. This is due to the possibility of the mother having slept with two men within a short time frame and thus, the chance of two separate ova (female eggs) being fertilised by two sperm cells, each sperm from a different man. Under such circumstances, the children will have different fathers; hence, it is important to determine whether the twins are identical or fraternal.
Moreover, paternity DNA tests might prove inconclusive if the alleged fathers are identical twins as their DNA profiles will be identical replicas of each others’. The child’s father in this case cannot be found through a DNA paternity test.
The Missouri identical twin fathers case
Identical twin brothers became father and uncle to a girl- but exactly which twin has what relationship to the girl? Each twin had been simultaneously having an affair with the mother of the girl and both slept with her on the same day. Identical twin father means that DNA paternity tests were of little use to solve the father or uncle dilemma- both would have equal probability of being the father. The mother’s testimony was the only evidence that the court could rely on. The story clearly shows up the limitation of current DNA testing.
Tags: dizygotic > dna paternity test > dna testing > DNA zygosity DNA test > monozygotic > paternity DNA tests > paternity test > twin test > Twin zygosity DNA test > twins dna testing > zygosity test
Test del DNA di Infedeltà
Posted on | September 23, 2009 | No Comments
Recenti adattamenti nei test del DNA permettono di determinare se è presente del materiale genetico estraneo, maschile o femminile, su un particolare oggetto. Se viene fornito un campione del presunto “traditore”, il test del DNA può stabilire se il campione in questione è un campione biologico e confermare il sesso del donatore del campione.
I campioni forniti possono variare da caso a caso, ma gli oggetti più comuni sono indumenti intimi, lenzuola, fazzoletti e profilattici. Il test del DNA può essere applicato a qualsiasi oggetto che sia sospettato di essere contaminato con materiale biologico.
La percentuale di successo dell’estrazione del DNA dipende dalla qualità del campione fornito: la maggior quantità di materiale biologico presente e la minor contaminazione dello stesso, garantiscono risultati migliori nello stilare il profilo del DNA. Detto questo, oggi i laboratorio di analisi del DNA hanno sviluppato molto la possibilità di ottenere il profilo del DNA da campioni anche limitati, quindi spesso riescono a ottenere un profilo totale o parziale da una vasta tipologia di campioni e in varie condizioni.
Test del DNA di Infedeltà
Confermare o Dissipare Sospetti Tramite il Test DNA di Infedeltà
Se hai sospetti di infedeltà del tuo partner, un test del DNA potrebbe essere un buon metodo per provare o smentire le tue paure. Basta sottoporre alle analisi dei campioni rilevanti ritenuti sospetti per determinare l’identità del probabile donatore del campione.
Per prima cosa, una procedura di questo tipo può stabilire se il DNA è maschile o femminile. A questo punto si riducono le possibilità del donatore. Il secondo passo è quello di ottenere un campione dal presunto traditore e metterlo a confronto con il campione non ancora identificato. Il risultato stabilisce se i campioni coincidono oppure no.
É importante ricordare che fare il test del DNA di infedeltà non porta a risultati definitivi. Con un processo di esclusione, è possibile arrivare a conclusioni certe, ma potrebbe rimanere una zona grigia, specialmente nell’identificazione di campioni del DNA sconosciuti. Non c’è garanzia che le prove raccolte portino a casi di infedeltà, spesso si può semplicemente accertare la presenza di materiale genetico estraneo. È importante ricordarsi che i risultati del test DNA sono possibili indizi e non la prova del comportamento di una persona o del suo tradimento. Possono essere usati per confrontare certe situazioni o per indirizzare dei ragionevoli dubbi verso una possibile risposta, ma non dare certezze.
Tags: esame dna > profilo del DNA > test di infedeltà > test di paternità > test dna
DNA Testing For Forensic Purposes
Posted on | January 30, 2009 | No Comments
One of the significant developments in Forensic science has been the use DNA Testing. This method of testing has helped solve many crimes that would not have been possible a few decades ago. More importantly it has been able to solve the crimes with a very high degree of accuracy resulting in avoidance of other circumspect or doubtful methods of investigation.
Every human being on the earth has genes. These genes are a unit of heredity and are also unique for each person. They are made up of made up of a number of molecules of DNA (Deoxyribonucleic Acid) in a particular sequence that is unique for each person. Thus a person’s genes can be identified and mapped. This system is known as DNA profiling.
In Forensic science the DNA from biological samples such as human hair, blood, semen, skin or saliva found at the scene of the crime is compared with the DNA of the suspect person and by the comparison it can be found whether the suspect person is innocent or guilty. This process is called genetic fingerprinting or DNA profiling. The system of DNA profiling is normally accurate only if the samples at the scene of the crime are not contaminated although as technology develops the capabilities of extracting DNA have improved immensely.
The first person to be sentenced to life imprisonment in the United Kingdom on the basis of evidence of DNA profiling was a rapist and murderer by the name of Colin Pitchfork. In the years 1983 and 1986, bodies of two young teenage girls were found. These girls had been raped and strangulated in a small town of Narborough, when each of the girls was returning home alone late in the day. There were no witnesses of the crimes, but the DNA profiles of the samples drawn from the scene of the two murders confirmed that the crime was perpetrated by the same person. Investigations led to the arrest of Richard Buckland, a young lad who confessed to murdering the second girl and denied that he had anything to do with the murder of the first girl. The DNA profile of Richard Buckland did not match with the DNA of the samples drawn at the scene of two murders. Further investigation led to the arrest of Colin Pitchfork in September 1987. The DNA profile of Colin’s blood sample matched with the DNA profile of the killer of the two girls. Colin Pitchfork confessed and was sentenced to life imprisonment in 1988 and became the first person to be convicted based on the evidence obtained from DNA profiling. Richard Buckland was the first person to be proved innocent of the crimes alleged to him by DNA profiling.
DNA testing can be done on samples of different material obtained from the scene of the crime. The non standard samples can be blood stains from clothes, tissues and tampons, clothes such as caps, bandanas, underwear, cigarette butts, gum, hair (at least four to five hair strands with hair roots), post mortem tissues. Standard samples are obtained from Buccal swabs (swabs of saliva taken from the cheek inside the mouth), blood, semen or sperm, or dry umbilical cord. The success rates vary depending on the samples and the condition they are in. The methods of preserving the samples also vary from preserving in dry ice to tubes to simple paper envelopes.
The National DNA Index (NDIS) has thousands of records of DNA profiles of samples drawn at the scene of the crime and as well as DNA profiles of body fluid samples furnished by known offenders. This data has been used to match and solve crimes and has resulted in over seventy thousand convictions. The NDIS and the DNAAU-II departments have helped in tracing missing persons and also in identifying unidentified bodies.
Forensic investigations based on DNA profiling have come a long way since the first studies were done during the 1980s. Paternity testing can confirm that the alleged father is not a father with one hundred percent accuracy and can conclude that the alleged father is the father with 99%+ accuracy. The results are accurate even when the mother is not tested. Infidelity or ancestry can also be tracked based on DNA profiles.
A lot of innocent victims have found freedom after DNA profiling proved that they were no way connected with the crime. As the testing methodologies are further refined, DNA Forensic testing will continue to cement itself as a very important tool in crime investigation.
Tags: dna paternity > dna paternity test > dna paternity testing > dna test > dna test kit > dna testing laboratory > dna tests > home dna test > home paternity test > paternity test kit
Test ADN de Paternidad : Envío de Muestras No Estándard (2nda parte)
Posted on | January 30, 2009 | 1 Comment
Indices de Éxito de Extracción de ADN desde muestras no estándar.
En la primera parte de este artículo, vimos algunos de los métodos no comunes para obtener ADN de un individuo para efectos de Pruebas de ADN. En este artículo, veremos el índice de éxito de extracción de ADN de varios tipos de muestras y como pueden variar de uno a otro.
Las muestras no estándar no siempre garantizan la obtención de un perfil de ADN. Aún con el uso de cotonetes bucales es posible que no se obtenga ADN, como en algunos casos donde la raspada bucal no ha sido hecha adecuadamente o que a los cotonetes les crece moho por condiciones de almacenamiento húmedos, en general, con este tipo de muestreo los problemas son menos del 2%- Por lo tanto, y dependiendo de la naturaleza de la muestra, usualmente se le relaciona un grado de Alto, Medio o Bajo de probabilidad de éxito de extracción de ADN de cada muestra (en algunos casos, se provee un porcentaje de probabilidad de éxito)
Test ADN de Paternidad : Envío de Muestras No Estándard
Alto (80%): Para muestras tales como manchas frescas de sangre o cabello con raíz, donde, para un laboratorio ADN calificado y con experiencia, la extracción del ADN es realizado sin complicaciones. En tales casos, y siempre y cuando la muestra haya sido manejada apropiadamente tanto en la recolección como en su posterior envío, uno puede esperar un alto grado de probabilidad de éxito en la extracción de ADN.
Medio (50%-60%): Para muestras tales como cepillos dentales o colillas de cigarrillo el éxito es influido por un numero de variables, incluyendo cantidad de uso y /o condiciones de almacenamiento. Por lo tanto, una colilla de cigarrillo completamente fumado, que se encuentra en un cenicero en casa, tiene mas probabilidades de éxito de extracción de ADN que un cigarrillo parcialmente fumado y encontrado en la calle y expuesto a los elementos (por ejemplo lluvia).
Bajo (20% – 30%): Para muestras tales como hueso o dientes, donde la extracción de ADN es un proceso complicado y requiere de mucho tiempo, estos deben ser normalmente manejados por un laboratorio altamente especializado. En estos casos, se recomienda que el individuo consulte con el laboratorio ADN su grado de experiencia, si aceptaran la muestra y su costo.
La clasificación descrita arriba es solamente una guía, ya que como hemos visto, lo importante no es solamente el tipo de muestra, sino que también otras variantes que pueden influir, tales como:
1. Condiciones no apropiadas de almacenamiento (ej. Ambiente húmedo, calor excesivo, etc.)
2. Manejo inadecuado de la muestra (contaminación con otra muestra de ADN o de tierra al tocar la muestra)
3. Presencia de ADN insuficiente (ej. Un cepillo dental usado frecuentemente vs. uno utilizado solo una vez)
También es importante mencionar que el índice de éxito dependerá mucho en la habilidad del laboratorio de realizar la prueba. No todos los laboratorios que pueden realizar una Prueba de Paternidad ADN con cotonetes bucales son capaces de extraer ADN por otros medios- Entre mas difícil el medio (Ej. Hueso y Diente), mayor grado de especialización y experiencia se requieren para incrementar las probabilidades de una extracción de ADN exitosa.
Finalmente, también es importante mencionar una vez más, que con muestras no estándar existe el riesgo que la extracción no funcione. Por lo tanto, una persona que esté considerando el envío de dicha muestra, especialmente donde solo exista una cantidad limitada de muestra, (por ej. Por que la persona falleció) deberá considerar esto. La selección de un laboratorio experimentado (con posible especialización ADN forense) minimizará éste riesgo.
Tags: adn paternidad > analisis de adn > Analisis de Paternidad > Kit de ADN > Kit de Prueba de paternidad > Laboratorio de pruebas de ADN > laboratorios de adn > paternidad ADN > prueba ADN > prueba paternidad > pruebas ADN > pruebas de adn > Pruebas de Paternidad > pruebas de paternidad cabello > test adn > Test de Paternidad
Test de Paternidad ADN: Envío de Muestras no Estandard (1ra parte)
Posted on | January 30, 2009 | 2 Comments
La prueba ADN de Paternidad es la forma más exacta de confirmar la relación biológica entre individuos. La manera estándar de recolectar muestras de los individuos a ser evaluados es a través del uso de cotonetes bucales / orales. Los Cotonetes bucales son relativamente fáciles de utilizar y son sin dolor, ya que el procedimiento implica simplemente frotar con el cotonete la parte interior de la boca y obtener una muestra de saliva. Adicionalmente, son fáciles de enviar por correo cuando se ordena una prueba. Por lo tanto, proveen un excelente medio para obtener ADN de un individuo.
Sin embargo, hay ocasiones en las cuales no es posible obtener una muestra directamente del individuo. Como por ejemplo en casos de muerte o personas perdidas o muestras tomadas de la escena de crimen. Por lo tanto, en estos casos, es posible utilizar muestras alternas (conocidas como Muestras no Estandard) para obtener el ADN de una persona con el propósito de Pruebas de ADN.
La siguiente lista provee información acerca de un número de muestras No Estándar que se puedan utilizar para obtener ADN a efectos de evaluación.
Test de Paternidad ADN: Envío de Muestras no Estandard
1. Muestras Biologicas Directas
Cualquier muestra de cabello enviada debe contener la raíz o el folículo. Pelo que ha sido cortado no produce AND significativo. Al enviar una muestra de cabello, uno debe asegurarse lo mas posible de no tocar la parte con el folículo y así evitar contaminación. El cabello puede ser enviado en un sobre normal de papel o plástico y deberá ser claramente marcado como una muestra no estándar. El laboratorio requerirá de al menos 6 a 10 cabellos (o lo mas posible) dependiendo de lo disponible. Entre mas cabellos estén disponibles, la mayor oportunidad de obtener un perfil ADN de ellos.
Muestras de sangre pueden ser en diversas formas, entre ellas sangre en si, manchas de sangre en papel u otro material (telas, muebles, etc.) Sangre seca, etc. La sangre era la manera mas común de obtener muestras de ADN para las Pruebas ADN de Paternidad, hasta el surgimiento del uso de cotonetes bucales. En la actualidad, es raramente requerido, ya que su obtención es a través de métodos invasivos, al contrario del método no invasivo e indoloro del cotonete bucal. Sangre fresca enviada en un tubo de ensayo proveerá una muestra mas que suficiente para obtener ADN. En los casos en que la sangre es enviada como mancha en alguna forma de material, entonces el éxito de la extracción dependerá del estado de la sangre y si ha sido expuesta a posible contaminación, ya sea de los elementos, contaminación humana y/o agentes químicos.
Tambien es posible extraer ADN de las uñas. Las uñas recien cortadas funcionan mejor y tienen mayor probabilidad de exito. Las uñas normalmente se recomiendan (ademas del cabello) en casos en que la persona ha recien fallecido. Es importante manejar las uñas con el minimo contacto directo para evitar contaminación. Las uñas pueden ser enviadas en un sobre normal de papel o plástico y deberá ser claramente marcado como una muestra no estándar.
En el caso de semen liquido, es recomendable que la muestra se absorba a través de un cotonete nuevo y que se deje secar al aire por una hora. En el caso de manchas de semen seco, o se envía el material directamente al laboratorio, o de lo contrario absorba la mancha a un cotonete nuevo, humedecido con agua destilada. Luego se deja secar al aire por una hora. Estas muestras podrán ser enviadas en un sobre normal de papel o plástico y deberá ser claramente marcado como una muestra no estándar.
Hueso
El Hueso es de los materiales más complicados de extraer ADN, y no todos los laboratorios ofrecen este servicio. El porcentaje de éxito depende del estado de los huesos (ej. Cuanto tiempo tiene la persona de fallecida, como ha sido preservado el cuerpo, etc.) Al enviar muestras de hueso, es recomendable que sean fragmentos de la diáfisis femoral o del Húmero de aproximadamente 2 gramos por individuo. Se recomienda que contacte al laboratorio que procesara la muestra, sea contactado previo a llevar las muestras para discutir el caso anticipadamente. La recolección de las muestras deberá ser por una persona calificada para hacerlo.
2. Artículos diarios que pueden contener ADN para efectos de evaluación.
Colilla de Cigarrillo
Las colillas de cigarrillo pueden ser una excelente fuente de ADN si la muestra no ha sido contaminada. Entre más ha sido fumado el cigarrillo, mayor probabilidad de que haya ADN presente. En casos en que el cigarrillo haya sido compartido, es muy probable que se obtenga un perfil mixto de ADN, en cuyo caso, se requerirá de un análisis mas especializado para separar ambos perfiles. El cliente deberá asegurarse que la muestra no se manipule del lado en que se ha inhalado al cigarrillo. Lo ideal es que se envien 2 – 4 colillas si es posible. Las colillas pueden ser enviadas en un sobre normal de papel o plástico y deberá ser claramente marcado como una muestra no estándar.
Cepillo Dental
Un cepillo dental puede ser una Buena fuente de ADN si la muestra no ha sido contaminada. Entre mas ha sido utilizado el cepillo, mayor cantidad de ADN estará disponible. Si el cepillo ha sido compartido, es posible que se obtenga un perfil mixto de ADN, en cuyo caso, se requerirá de un análisis mas especializado para separar ambos perfiles. El cliente deberá asegurarse que la muestra no se manipule del lado de las cerdas para evitar contaminación. También el cepillo deberá secarse al aire por 30 – 60 minutos para asegurarse que este completamente seco previo a envío al laboratorio. El cepillo puede ser enviado en un sobre normal de papel o plástico y deberá ser claramente marcado como una muestra no estándar.
Estampilla y Sobre
Sobres y Estampillas que han sido lamidos pueden ser una fuente de AND a efectos de evaluación de Paternidad por ADN. Sin embargo, el índice de éxito de éste método puede variar ya que no es siempre posible saber si la estampilla o sobre han sido lamidos o no. En casos en que no ha habido contacto con la saliva de una persona, es claramente imposible obtener ADN. Por lo tanto, la muestra es usualmente clasificada como poco probable de obtener éxito de extracción. Al enviar las muestras es importante asegurarse de no tocar los sellos o la parte trasera de la estampilla para minimizar contaminación.
Goma de Mascar
La goma de mascar o chicle, puede ser una buena fuente de ADN si la muestra no ha sido expuesta a contaminación por los elementos. La Goma sin azúcar es preferible a la goma normal. Es importante no tocar el chicle con los dedos, ya que esto puede producir contaminación. La goma puede ser enviada en un sobre normal de papel o plástico y deberá ser claramente marcado como una muestra no estándar.
Tags: adn paternidad > analisis de adn > Analisis de Paternidad > Kit de ADN > Kit de Prueba de paternidad > Laboratorio de pruebas de ADN > laboratorios de adn > paternidad ADN > prueba ADN > prueba paternidad > pruebas ADN > pruebas de adn > Pruebas de Paternidad > pruebas de paternidad cabello > test adn > Test de Paternidad
Test ADN de paternité : Le dépôt énchantillons non standards (partie 1)
Posted on | January 16, 2009 | No Comments
Le test de paternité d’ADN est le moyen le plus sûr pour confirmer les rapports biologiques entre individus. La méthode standard de prélèvement des échantillons chez les personnes à examiner se fait à l’aide de tiges de prélèvement buccal. Les tiges de prélèvement buccal sont relativement faciles à utiliser et n’occasionnent aucune douleur puisque le procédé demande de simplement frotter la tige contre la paroi intérieure de la bouche afin de prélever des échantillons de salive. En plus, elles peuvent être facilement envoyées par la poste au client quand celui-ci commande un test. Elles sont par conséquent un moyen excellent d’obtention d’ADN pour chacun.
Cependant, il arrive qu’il soit parfois impossible d’obtenir directement un échantillon provenant d’une personne, comme par exemple dans le cas d’une personne disparue ou décédée ou d’échantillons prélevés sur une scène du crime. Il convient par conséquent d’utiliser dans ce cas des échantillons alternatifs (appelés non standards), pour obtenir l’ADN de cette dernière.
La liste suivante fournit des informations sur un certain nombre d’échantillons non standards pouvant être utilisés pour le test ADN.
1. Échantillons biologiques directs
Les cheveux prélevés doivent conserver leur racine ou follicule. Les cheveux qui sont coupés ne produiront aucun ADN significatif. Lorsque l’on rend l’échantillon de cheveux, l’on doit veiller à ne pas toucher le follicule pour éviter toute contamination. Les cheveux peuvent être envoyés par une enveloppe normale en plastique ou en papier et clairement marquée échantillon non standard. Le laboratoire exigera au minimum 6-10 cheveux (ou plus si possible) selon la disponibilité. Plus il y a des cheveux disponibles, plus il est possible d’obtenir de meilleurs résultats du test de paternité ADN.
Les prises de sang peuvent être de diverses formes à savoir le sang prélevé ordinairement, les taches de sang sur du papier ou autre matériel (tissus, habits ou meubles), desséché etc. Le sang jusqu’à l’apparition des tiges de prélèvement buccal fut l’échantillon le plus utilisé pour les tests ADN. La méthode de prise de sang est de nos jours rarement demandée car celle par frottis buccal n’est ni douloureuse ni invasive. Le sang frais envoyé par tube normal est plus que parfait comme échantillon pour obtenir de l’ADN. Dans les cas où le sang prélevé est celui d’une tache sur un quelconque matériel, le résultat du prélèvement dépendra de l’état du sang et du fait qu’il ait été exposé ou non à toute contamination possible telle que les éléments extérieurs, la contamination humaine et/ou les agents chimiques.
Les ongles
Il est également possible d’obtenir de l’ADN à partir des ongles. Les ongles fraîchement coupés sont les mieux adaptés pour obtenir un bon résultat. Les ongles sont généralement recommandés (à part les cheveux) dans les cas où la personne est récemment décédée. Il est important de manipuler les ongles avec moins de contact direct possible pour éviter toute contamination. Les ongles peuvent être envoyés par une enveloppe normale en plastique ou en papier et clairement marquée échantillon non standard.
Le sperme
Dans le cas du sperme liquide, il est recommandé de prélever l’échantillon avec un coton-tige et le laisser sécher à l’air libre pendant environ une heure. Dans le cas de taches sèches de sperme, soit envoyer le tissu directement au laboratoire ou absorber la tache à l’aide d’un coton-tige propre humidifié à d’eau distillée. Le laisser sécher ensuite à l’air libre pendant environ une heure. Les échantillons peuvent être envoyés par une enveloppe normale en plastique ou en papier et clairement marquée échantillon non standard.
Les os
L’échantillon des os est l’un des éléments les plus difficiles à manipuler pour extraire l’ADN et tous les laboratoires d’ADN n’offrent pas ce genre de service. La probabilité d’une bonne extraction dépendra de l’état des os (par exemple période écoulé depuis le décès de la personne, comment est-ce que le corps a été conservé, etc). Il est généralement recommandé de prélever comme échantillons, des fragments provenant de l’intérieur du fémur ou de l’humérus et pesant approximativement 2g par personne. Il est aussi conseillé que le laboratoire chargé de la manipulation de l’échantillon soit contacté pour discuter du cas avant de prendre l’échantillon. La collecte d’échantillons devrait être effectuée par un personnel sanitaire.
2. Eléments de touts les jours pouvant contenir de l’ADN pour un test
Le mégot de cigarette
Les mégots peuvent être une excellente source d’ADN si l’échantillon n’a pas été contaminé. Plus la cigarette a été fumée plus l’ADN est susceptible d’être disponible. Si la cigarette a été partagée il est probable d’obtenir un profil ADN mélangé, dans ce cas une analyse spécialisée est requise pour séparer les profils. Le client devrait s’assurer que l’échantillon n’est pas été manipulé par le bout utilisé pour inhaler la fumée. L’idéal serait qu’il fournisse 2-4 mégots de cigarette si possible. Le mégot peut être envoyé par une enveloppe normale en plastique ou en papier et clairement marquée échantillon non standard.
Brosse à Dents
Une brosse à dents peut être une bonne source de d’ADN si l’échantillon n’a pas été contaminé. Plus la brosse à dents a été utilisée plus l’ADN est susceptible d’être disponible. Si la brosse à dents a été partagée il est probable d’obtenir un profil ADN mélangé, dans ce cas une analyse spécialisée sera requise pour séparer les profils. Le client devrait s’assurer que l’échantillon n’est pas été manipulé par les extrémités des brins pour éviter toute contamination. La brosse devrait être par la suite séchée à l’air sec pendant environ 30-60 minutes pour s’assurer qu’elle l’est correctement avant de l’expédier au laboratoire. La brosse à dent peut être envoyée par une enveloppe normale en plastique ou en papier et clairement marquée échantillon non standard.
Enveloppe et timbre
Les enveloppes et timbres utilisés avec la salive peuvent être une source d’ADN pour le test de paternité. Cependant, la probabilité d’obtention de bons résultats sur ce type d’échantillon est très vague puisqu’il n’est pas possible de toujours savoir si le timbre et l’enveloppe ont été utilisés avec la salive ou pas. Dans le cas où il n’y a eu aucun contact avec la salive du sujet, il est clairement impossible d’obtenir de l’ADN. Pour cette raison, ce type d’échantillon est généralement classé comme ayant un faible taux de réussite d’extraction. Il est important lors du dépôt de l’échantillon de s’assurer de ne pas toucher la surface collante et le dos du timbre pour éviter toute contamination possible.
Chewing-gum
Le chewing-gum peut être une bonne source d’ADN si l’échantillon n’a pas été exposé à des agents contagieux. Le chewing-gum sans sucre est préféré par rapport au normal. Il est important de ne pas essayer de toucher le chewing-gum avec les doigts pour éviter toute contamination. Le chewing-gum peut être envoyé par une enveloppe normale en plastique ou en papier et clairement marquée échantillon non standard.
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