The isochromosome 12p (i(12p)) in fibroblasts of 3 patients with Pallister-Killian syndrome and one decreased prematurely born neonate, was characterized by fluorescent in situ hybridization (FISH) using chromosome 12-specific DNA probes. FISH is a useful technique for rapid and reliable detection and characterization of the i(12p) chromosome in Pallister-Killian patients. Detection was possible also in interphase cells. In addition, the in vitro selection against i(12p) cells at different passages in fibroblast cultures of two patients was monitored.

Total activities of acid hydrolases in liver of two patients with mucopolysaccharidosis are decreased for beta-galactosidase, alpha-galactosidase, and arylsulfatase A; total activities of four other hydrolases are normal or increased. The isoenzyme distribution of five hydrolases (beta-glucuronidase, alpha-glucosidase, beta- galactosidase, N-acetyl-beta-glucosaminidase, and alpha-galactosidase) is ábnormal in that the isoelectric points (by isoelectric focusing) of these enzymes are more acid than in control liver. Along with the isoenzyme abnormalities different kinds of glycolipids were stored in kidney, liver, and brain. The isoenzyme abnormalities can be reproduced in vitro by addition of chondroitin sulfate to a homogenate of normal liver, suggesting that stable binding occurs between mucopolysaccharides and the hydrolase molecules. After the addition of chondroitin sulfate, the total activity of beta-galactosidase is inhibited, whereas other hydrolases are affected only slightly or not at all.

A review of 63 patients with 45X karyotype (Turner's syndrome) admitted to a hospital from 1972 to 1985 showed that 20 (32%) had one or more major cardiac malformations (mostly coarctation and aortic stenosis). Four (20%) died in the neonatal. One infant had mitral stenosis and severe aortic stenosis and died at the age of 35 days. The three (15%) other patients who died had a typical hypoplastic left heart syndrome, with an atretic aortic valve in two and pinpoint aortic valve in one. Turner's syndrome was clinically suspected in three of the cases. One of these had mosaicism (46XX,45X) the others had a 45X pattern. During the same period (1972-85) 39 patients (14 girls and 25 boys) were admitted with diagnosis of hypoplastic left heart syndrome. Three (21.4%) girls had a 45X karyotype. The high incidence of hypoplastic left heart syndrome in Turner's syndrome and of Turner's syndrome in girls with hypoplastic left heart syndrome suggests that hypoplastic left heart syndrome can be another expression of the 45X karyotype.

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Case reports a karyotype of 46,X,del(Y)(ql 1). The deleted Y had neither C positive nor brightly fluorescing bands ( figure). The Y chromosome of the proband's father was normal in appearance.