The distributions of seven genetic polymorphisms in patients with Down's syndrome

The distributions of serum complement C3, haptoglobin and transferrin and erythrocyte acid phosphatase, adenylate kinase, 6-phosphogluconate dehydrogenase and phosphoglucomutase 1 polymorphisms were determined in 171 persons with Down's syndrome and in a control group of 200 normal, healthy persons. In Down's syndrome, unusual phenotypic proportions were observed in the haptoglobin and acid phosphatase systems, while deviations from Hardy-Weinberg equilibrium were found in the complement C3, acid phosphatase and phosphoglucomutase 1 polymorphisms. The proportion of persons with Down's syndrome of acid phosphatase type A declined linearly with age.