Interstitial deletion of the short arm of chromosome 4 in a boy with mild psychomotor retardation and dysmorphism.

A 17-month-old boy is reported with 46,XY,del(4) (p15.2p15.32). He had mild psychomotor retardation and multiple minor anomalies, without growth retardation or microcephaly, which differs from the classical 4p--syndrome (Wolf-Hirschhorn syndrome). The activity of dihydropteridine reductase, a genetic marker for chromosome 4p15.3, was half that in a normal control.