Objective: The presence of a 47, XYY karyotype in boys with pervasive developmental disorders (PDDs) has rarely been described in the past. Herein, 2 boys with PDDs and a supernumerary Y chromosome are presented.
Methods: The case histories of the 2 patients are described along with the results of associated testing. The literature on psychosocial development as well as brain morphology and physiology in males with 47, XYY karyotypes is reviewed.
Results: Both boys had presentations typical of PDDs, one with autistic disorder and the other with PDD not otherwise specified.
Conclusion: The finding that, in a clinic for children with developmental disorders, 2 of 40 male referrals had 47, XYY karyotypes suggests that the rate of this sex chromosome anomaly may be increased in PDDs. An extra Y chromosome may be related to abnormal brain development, which may, in turn, predispose vulnerable males to PDDs.