Galactokinase deficiency: clinical and biochemical findings in a new kindred.

The second reported case, in the United States, of hereditary galactokinase deficiency characterized by galactosuria and cataracts is presented. In contrast to others, our patient had uncontrollable seizures and severe neurologic deterioration which began at age 17 years. The relationship of these events to the galactokinase deficiency is unknown, but they may be related. The ratio of galactokinase activity to transferase activity in erythrocytes was found to be a more reliable determinant of heterozygosity than the measurement of erythrocyte galactokinase activity per se. The disorder is inherited in an autosomal recessive manner. Fibroblasts from the proposita possessed no galactokinase activity. Determination of galactokinase activity in skin fibroblasts appears to be a reliable method for the detection of heterozygous individuals; it should permit prenatal diagnosis of the disorder when cultivated amniotic fluid cells are used. Avoidance of lactose by heterozygous individuals may be justified until the possibility of development of cataracts in them is resolved.