The question of causality vs concomitance of nodulocystic acne (NCA) and XYY genotype is examined. The results of our previous pilot study on the frequency of the XYY genotype in prisoners (four in 100) and outpatients (two in 100) with NCA are discussed in relation to the 44% (seven in 16) frequency of NCA in three series of XYY subjects in whom the presence of NCA was sought and recorded. The 2% XYY frequency in NCA outpatients (11 times the 0.18% XYY incidence in neonatal males), 4% XYY frequency in prisoners with and none in prisoners without NCA, and 44% frequency of moderate to severe acne in known XYY's (14 times the 3% NCA incidence in XY boys) suggests an association between NCA and the XYY genotype. The XYY subjects appear to have NCA commonly, whereas any one NCA patient will only very rarely have an XYY genotype.
Voorhees JJ, Wilkins JW, Hayes E, Harrell ER. Nodulocystic Acne as a Phenotypic Feature of the XYY GenotypeReport of Five Cases, Review of All Known XYY Subjects With Severe Acne, and Discussion of XYY Cytodiagnosis. Arch Dermatol. 1972;105(6):913-919. doi:10.1001/archderm.1972.01620090079019