Premature arteriosclerosis and thromboembolic events are well-known complications of homozygous homocystinuria due to cystathionine synthase deficiency. It is unknown whether heterozygosity for homocystinuria predisposes to premature vascular disease. We explored the frequency of excessive homocysteine accumulation after standardized methionine loading in 75 patients presenting with clinical signs of ischemic disease before the age of 50:25 with occlusive peripheral arterial disease, 25 with occlusive cerebrovascular disease, and 25 with myocardial infarction. In seven patients in each of the first two groups but in none of the patients in the third group, heterozygosity for homocystinuria was established on the basis of pathological homocysteinemia after methionine loading and cystathionine synthase deficiency in skin fibroblast cultures. Because the frequency of heterozygosity for homocystinuria in the normal population is 1 in 70 at the most, we conclude that this condition predisposes to the development of premature occlusive arterial disease, causing intermittent claudication, renovascular hypertension, and ischemic cerebrovascular disease.

The prevalence of malnutrition and its predictive value for the incidence of complications were determined in 155 patients hospitalized for internal or gastrointestinal diseases. At admission, 45% of the patients were malnourished according to the Subjective Global Assessment (physical examination plus questionnaire), 57% according to the Nutritional Risk Index [(1.5 X albumin) + (41.7 X present/usual weight)], and 62% according to the Maastricht Index [(20.68 -(0.24 X albumin) -(19.21 X transthyretin (prealbumin) -(1.86 X lymphocytes) -(0.04 X ideal weight)]. Crude odds ratios for the incidence of any complication in malnourished compared with well-nourished pa tients during hospitalization were 2.7 (95% Cl: 1

A 10-year-old boy with microcephaly, stunted growth, mental retardation, café-au-lait spots and immunodeficiency is described. An older brother of the patient had the same clinical symptoms and a more severe immunodeficiency. Cytogenetic studies in the proband revealed a typical form of chromosome instability with multiple rearrangements of chromosomes 7 and 14. Such abnormalities were also present, though in very low frequencies, in the father and three of the phenotypically normal sibs. The similarity of the symptoms in the two sibs, the close consanguinity of their parents and the results of the cytogenetic studies in the family favour the hypothesis that the disorder is an inherited one. The clinical features and the chromosome aberrations as present in the proband are usually found in chromosomal breakage syndromes, but it was possible to exclude each of the classical chromosomal breakage syndromes on clinical and/or cytogenetic grounds.

ABSTRACT. Objectives. To further define the clinical spectrum of the disease for pediatric and metabolic spe cialists, and to suggest that the general pediatrician and pediatric neurologist consider succinic semialdehyde de hydrogenase (SSADH) deficiency in the differential di agnosis of patients with (idiopathic) mental retardation and emphasize the need for accurate, quantitative or ganic acid analysis in such patients.Patients. The clinical features of 23 patients (20 fam ilies) with SSADH deficiency (4-hydroxybutyric acid uria) are presented. The age at diagnosis ranged from 3