Inadvertent diagnosis of male infertility through genealogical DNA testing.

T he potentially informative relationship between Y chromosomes and patrilinearly inherited surnames has led to a major expansion in the number of commercial companies offering Y chromosomal DNA polymorphism analysis to members of the public; because of the geographical specificity of Y chromosomal types, many companies also offer to deduce ‘‘ancestry’’. As the number of markers used in these tests increases, so does the probability of inadvertently diagnosing male infertility through the detection of Y chromosomal deletions. Using commercially typed Y markers, we here report the ascertainment of such deletions in general population samples.