Monosomy, trisomy, fragile sites, and rearrangements of chromosome no. 1 in a mentally retarded male with multiple congenital anomalies.

A 17-year-old male was referred for evaluation because of short stature and severe mental retardation. Major clinical findings included microphthalmia, micrognathia, low-set ears, a prominent beaked nose, clubbing of digits, and premature graying of hair. Cytogenetic analysis revealed a 45,XY,-1/46,XY/47,XY,+1 mosaicism in lymphocytic culture, a 45,XY,-1/46,XY mosaicism in skin fibroblasts, and fra(1p) sites in 2% of the metaphases from lymphocyte, fibroblast and bone marrow cultures. Post-zygotic non-disjunction causing this mosaicism is believed to be responsible for the patient's phenotype.