Although single nucleotide polymorphism chromosomal microarrays identify areas of small genetic deletions or duplications, they can also reveal regions of homozygosity indicative of consanguinity. As more nongeneticists order single nucleotide polymorphism microarrays, they must prepare for the potential ethical, legal, and social issues that result from revelation of unanticipated consanguinity.

We describe an infant with multiple congenital anomalies who underwent single nucleotide polymorphism microarray testing.

The results of the single nucleotide polymorphism microarray revealed several large regions of homozygosity that indicated identity by descent most consistent with a second-degree or third-degree relative mating (e.g., uncle/niece, half-brother/sister, first cousins). The mother was not aware of the test's potential to reveal consanguinity. When informed of the test results, she reluctantly admitted to being raped by her half-brother around the time of conception.

During the pretesting consent process, providers should inform parents that single nucleotide polymorphism microarray testing could reveal consanguinity. Providers must also understand the psychological implications, as well as the legal and moral obligations, that accompany single nucleotide polymorphism microarray results that indicate consanguinity.