![]() The specific form of congenital chimerism in our case study was determined to be tetragametic chimerism (tetra = four gametes). ![]() Unbeknownst to the family and to the fertility clinic, the reason for the test’s false negative result was that the father harbored more than one genome, a condition called chimerism. In this paper, we present a case where the gold standard STR-based DNA paternity test repeatedly excluded the proband from being the biological father, despite the fact that the child was conceived by a semen sample provided by the proband. ![]() In cases where a baby was conceived in a fertility clinic, false negative tests can have ramifications for the clinic and staff. A negative result, where the proband is excluded as the father of the child, has serious consequences to families ranging from broken trust (fidelity concerns), divorce, lost child support, or denied immigration. Understanding these is of critical importance. This technology was developed in the 1980s and has known limitations and failures. (With less than 60% of all surveyed paternity testing laboratories reporting data to the American Association of Blood Banks in 2010, this is a considerable underestimate.) Additionally, an unknown number are self-administered at home.Ĭurrently, the gold standard technology used for these tests is a PCR-based assay that amplifies short tandem repeat (STR) regions within the tested person’s DNA. In the USA, well over 382,000 legal paternity tests are ordered annually. Common reasons for testing are child custody, child support, and immigration cases. Parental (paternity/maternity) DNA testing is indicated where a parent-child relationship requires confirmation. We offer specific suggestions for improving laboratory reporting and creating clinical guidelines to aid in identifying and rectifying future cases of false exclusions of paternity due to chimerism. This case underscores the possibility that some allegations of fertility clinic missteps may be explained by undiagnosed chimerism, a condition where an individual harbors two distinct genomes. His paternity was subsequently affirmed and the fertility clinic exonerated of claims of a semen sample mix-up. Additional tissue samples were analyzed and family studies were conducted at paternity and forensic laboratories using STR-based DNA tests to elucidate the proband’s condition of congenital tetragametic chimerism. Microarray technology was utilized to confirm biological relatedness, which revealed an avuncular (uncle/nephew) relationship. The proband, a 34 year-old male, contacted our research group when routine blood testing revealed discrepant blood types between the parents and the baby, repeat paternity tests were negative (excluding the proband as the baby’s father), and the fertility clinic found no evidence of any wrongdoing. However, we report a case where, despite repeat negative paternity test results, the alleged father (referred to as “the proband”) was confirmed to be the baby’s father. In the fertility clinic setting, a negative DNA paternity test result usually suggests a sample mix-up likely occurred at the testing company or in the clinic.
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