Despite having two unique genomes, most congenital chimera manifest no outward signs or symptoms of the condition and remain undiagnosed throughout their lives. Undiagnosed chimerism confounds gold standard molecular forensic and relationship tests. In forensics, observing only one of two genomes from congenital or acquired chimerism may cause mismatches between evidence and reference samples, leading to wrongful convictions or exonerations. In relationship testing, false exclusions of paternity and maternity have been documented. Cases of false parentage exclusions have resulted in loss of child custody. Possible financial losses include loss of child support and loss of inheritances. Immigration opportunities for families may be lost when the DNA tests do not confirm declared relationships. Greater analytical sensitivity of newer molecular tests should improve detection of chimerism, but errors due to tissue sampling limitations will continue to be problematic. Studies of chimerism are needed to determine the condition’s prevalence and the tissues that most frequently manifest both genomes.
KeywordsParental DNA testing Molecular forensic testing Chimerism Microchimerism DNA testing recommendations
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