Advances in molecular DNA sequencing allow researchers to obtain high-quality DNA samples from small quantities of hair, feathers, scales, or other body parts. These so-called noninvasive samples are an improvement over older allozyme and DNA sampling techniques that often required larger samples of tissue and blood or the destruction of the studied organism. Noninvasive genotyping is widely utilized in conservation efforts, where capture and sampling may be difficult or disruptive. Additionally, in medicine, this technique is being applied in humans for diagnosis of genetic disease and for the development of personalized genetic medicine.
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Conservation
In conservation, noninvasive genotyping has been used to supplement traditional techniques with broadly ranging levels of success. Modern DNA amplification methods allow researchers to use fecal or hair samples collected from the field to assess basic information about the specimen, including sex or species. Despite the potential that noninvasive genotyping has in conservation genetics efforts, the efficiency of this method is in question, as field samples often suffer from degradation and contamination or are difficult to procure.
Fetal genotyping
The most common use of noninvasive genotyping in medicine is non-invasive prenatal diagnosis (NIPD), which provides an alternative to riskier techniques such as amniocentesis. With the discovery of cell-free fetal DNA in maternal plasma, NIPD has become a popular method for determining sex, paternity, aneuploidy, and the occurrence of monogenic diseases as it requires only a simple blood sample.
Tumor detection
This same technique is also utilized to identify the incidence of tumor DNA in the blood, which can both provide early detection of tumor growth and indicate relapse in cancer. Circulating tumor DNA can be found in the blood before metastasis occurs and, therefore, detection may enhance survival rates in cancer patients.