Forensic DNA Testing & Specialty Services
The OSU Human Identity Testing Laboratory offers forensic DNA typing and consultation to law enforcement agencies and attorneys throughout the country. Our lab is experienced in obtaining DNA from forensic type evidence, including body fluid stains, bone and body tissue and even touched items. Our lab has extensive experience with extracting DNA from bones, teeth and tissues in varying stages of decomposition.
Please contact the OSU Human Identity Testing laboratory at 1-800-299-7919 for additional information.
Forensic DNA Testing
The OSU Human Identity Testing Laboratory offers forensic DNA typing and consultation to law enforcement and attorneys around the country. The lab is experienced in obtaining DNA from forensic type evidence and producing a DNA profile that is probative. In addition, we can provide consultation to law enforcement and attorneys regarding work previously performed by a different DNA typing laboratory.
Identification Of Human Remains
Medical examiners and coroners are often called upon to identify human remains. Techniques that are routinely used in their facilities may be insufficient to determine identity when there is a lack of ante-mortem information or when remains have been exposed to the elements or buried for extended periods.
Our extensive experience in the human identification field has allowed us to improve our procedures for recovering DNA from difficult sample types, such as touch DNA, bone, paraffin embedded tissues, teeth, and other biological samples in sufficient amounts to produce a DNA profile. In addition, our laboratory information system allows for precise documentation and tracking of each case processed and includes a robust capability for statistical calculations in relationship cases involving complex pedigrees.
By using specialized extraction techniques and then performing DNA typing of 25 autosomal and 23 Y-chromosome short tandem repeat (STR) markers, our laboratory is able to obtain DNA profiles that can be compared with the profiles of individual who are thought to be parents, siblings or other relatives in order to identify the remains. A known sample from the deceased individual can also be used as a comparison sample in cases where there are no known relatives.
Typical turn-around-time from receipt of all samples to report is 3-5 days. Extenuating circumstances may lead to an increase of this time. A report will be issued that includes or excludes the tested relationship between the deceased individual and the reference family members. When comparing the deceased to a reference sample, the report will provide a likelihood of how often that particular profile occurs in the General Population.
Please contact the OSU Human Identity Testing laboratory at 1-800-299-7919 to discuss your case and to obtain the required documentation forms.
Maternal Cell Contamination
Interpretation of prenatal analyses is one of the most complex areas in genetic testing. Invasive methods, such as chorionic villus sampling (CVS) and the collection of amniotic fluid, are often performed to obtain DNA for genetic testing because of a family risk for a genetic disorder. Contamination of a fetal sample with cells of maternal origin is a potential source of error in diagnostic prenatal testing, as it may result in analysis of the maternal rather than the fetal DNA. Although contaminating blood may be visualized in an amniotic fluid sample, the source of the blood, either maternal or fetal, cannot be assessed without maternal cell contamination (MCC) studies. In CVS samples, maternal decidua may be difficult to separate from chorionic villi. The molecular diagnostician must be confident that the sample used for analyses are purely fetal in origin in order to provide accurate results.
The OSU Human Identity Testing laboratory uses 20 genetic markers to determine whether maternal DNA is present in the fetal DNA sample that will be tested by a molecular lab to identify genetic conditions. Even low levels of maternal contamination can negatively impact molecular genetic testing. Our testing can provide assurance that future genetic testing will provide an accurate result for genetic risk for the fetus.
Additionally, MCC studies can serve as a quality assurance measure to ensure that the biological mother is matched with her fetus, thereby minimizing the possibility of a sample mix-up when future DNA testing is performed.
One method of monitoring the engraftment of transplanted bone marrow in a recipient is to exploit differences in the genetic markers of the donor and the recipient. One class of highly polymorphic markers of this type is short tandem repeats (STRs) that can be efficiently amplified using the polymerase chain reaction (PCR). A typical STR marker will be composed of 5-10 alleles in the population, making it unlikely that unrelated and even related individuals will yield identical DNA typing results for the genetic systems tested by our laboratory. Moreover, since all alleles at a locus are amplified with equal efficiency, it is possible to quantitate the relative contributions of DNA from the donor and the recipient present in a mixture. This is important in the monitoring of engraftment since the recurrence of hematopoietic activity in the recipient can occur resulting in a mixed cell population in the circulation, which can be prognostic to a clinician in terms of a relapse of disease.
Evaluating engraftment at the OSU Human Identity Testing laboratory employs the use of a collection of as many as 25 STR systems that are capable of identifying the source(s) of DNA in a sample. In the case of bone marrow transplantation, the testing available would be sufficient to identify with certainty if circulating cells in a recipient were from a donor and would identify with a high probability if circulating cells in a recipient were from the donor (with the exception of identical twins). In addition, our STR analysis methodology employs the use of fluorescent labels to visualize PCR products. It is therefore a simple task to accurately quantify the relative contributions of donor and recipient cells to a mixed cell population. The sensitivity of our testing program is such that mixtures containing less than 5 percent of one cell population can be reliably detected.
If monitoring is to be performed, we first need pre-transplant specimens. Pre-transplant samples may be blood samples or buccal swabs from both the donor and recipient. The pre-transplant testing allows us to identify those genetic markers in which the donor and recipient differ in their DNA profiles. Donors do not need to be re-collected post-transplant. Post-transplant recipient samples utilize the markers that were determined to differ during pre-transplant testing of the donor and the recipient so that we can determine recurrence of recipient cells.
Once transplantation occurs, a series of post-transplant blood samples should be evaluated both for long-term engraftment and for possible re-appearance of host hematopoietic activity. The recommended schedule for post-transplant monitoring is:
- One week post transplant
- One month post transplant
- Three months post transplant
- Six months post transplant
- One year post transplant
- Three years post transplant
- Five years post transplant
Testing should also be done anytime recurrence is suspected.
Reports will identify the source of circulating white cells in the recipient and state whether or not there is evidence of a mixture of donor and recipient cells. If a mixture that indicates returning recipient cells is present, the report will further quantify the relative contributions of cells from each individual to the mixture. Our laboratory uses validated mixture studies to ensure that we can detect as few as 5 percent circulating cells from the transplant recipient. Turn around time for reports averages three working days.
DNA can be extracted from paraffin embedded tissues in order to compare the DNA profile with a reference sample(s). This can be useful not only for relatedness testing but also to confirm that the pathology lab is reporting results from the correct patient.
The preferred sample for this testing is 20 x 5μm slices cut with a microtome from the paraffin block. The slices are placed in a single layer between two sheets of glassine weigh paper or other wax coated paper that will not adhere slices. The encased slices should then be protected within a cardboard or plastic side holder. The slices can be stored and shipped at room temperature. Slices from multiple paraffin blocks and/or reference sample(s) can be compared. In most case, buccal swabs are collected from a reference individual but any biological sample can be used as a known reference sample.
Once our lab receives all samples to be tested [generally paraffin slices and a reference sample(s)], processing generally takes 3-5 days. A report will be generated that includes a table of loci tested and the resulting alleles, a calculation of the number of individuals in a defined population who have this combination of alleles and a conclusion as to whether the unknown paraffin sample is consistent or not consistent with a reference sample.