Borderline galactosemia.

A family with combined heterozygosity for "classical" galactosemia (deficiency of uridyl-transferase) and for galactokinase deficiency is reported. The proband, who had this genetic combination was detected as newborn in the ordinary screening for galactosemia. A lactose tolerance test at the age of three months proved normal and he has no symptoms or signs on ordinary diet. The mother of the proband was not only heterozygote for "classical" galactosemia and galactokinase deficiency but also for the Durarte variant. She had a substantial urine excretion of galactose and high serum galactose after an oral lactose load. She had no clinical symptoms or signs. Patients with combined heterozygosity for galactosemia may develop cataracts and should be followed by clinical examinations.