LETHAL PALLISTER-KILLIAN SYNDROME - PHENOTYPIC SIMILARITY WITH FRYNS SYNDROME

The Pallister-Killian syndrome is a sporadic multiple congenital anoma ly syndrome characterized by ''coarse'' face, profound mental retardat ion, and epilepsy Chromosomes of peripheral lymphocytes are usually no rmal, but tissue cultures show varying degrees of mosaicism for isochr omosome 12p. In babies who die neonatally of severe malformations, inc luding diaphragmatic hernia, and who also have a ''coarse'' face, acra l hypoplasia, and other internal anomalies, Fryns syndrome is more lik ely to be suspected than Pallister-Killian syndrome, especially if kar yotyping is unavailable or if peripheral lymphocytes have a normal chr omosome constitution. An initial diagnosis of Fryns syndrome had to be modified in 3 successive newborn infants since chromosome analysis or in situ hybridization with a chromosome 12 probe on kidney tissue dem onstrated the mosaic aneuploidy characteristic of Pallister-Killian sy ndrome. These 3 patients confirm that a similar pattern of malformatio ns can be present in both conditions at birth. It consists of ''coarse '' face, acral hypoplasia, diaphragmatic hernia, and other defects. Ne wborn infants who present this phenotype, but lack a conclusively norm al chromosome test, may not have Fryns syndrome. A diagnosis of Fryns syndrome should be made carefully to avoid the risk of inappropriate g enetic counseling. (C) 1994 Wiley-Liss, Inc.