PREZYGOTIC ORIGIN OF THE ISOCHROMOSOME-12P IN PALLISTER-KILLIAN-SYNDROME

Pallister-Killian syndrome is a rare disorder comprising multiple cong enital. anomalies, streaks of hypo(hyper)pigmentation, seizures, profo und mental retardation, and the presence of an extra metacentric chrom osome i(12)(p10), usually limited to skin fibroblasts. The mechanism a nd parental origin of the extra chromosome i(12)(p10) are unknown. Her e, we present a girl with Pallister-Killian syndrome and the i(12)(p10 ) in 50% of cultured skin fibroblasts. Using microsatellite DNA marker s of chromosome 12p, we detected 3 alleles-including 2 different allel es of maternal origin-in cultured skin fibroblasts, suggesting that th e tetrasomy 12p is the result of a prezygotic event, with a nondisjunc tion event during maternal meiosis. (C) 1997 Wiley-Liss, Inc.