Maple syrup urine disease in a Bedouin tribe: pre- and postnatal diagnosis.

Maple syrup urine disease (MSUD) was diagnosed in four Bedouin infants as a result of the lack of branched-chain keto amino acids (BCKA) decarboxylase activity in leukocytes and skin fibroblasts. Second trimester amniocenteses were performed in five at risk pregnancies for measurement of BCKA decarboxylase. The activity measured in amniocytes was undetectable in two of them. Pregnancy was terminated only in one case and the second continued to term. The diagnosis of MSUD was confirmed in tissues of one aborted fetus, and in leukocytes of the liveborn infant. The other three pregnancies, in which normal enzymatic activity was found in the amniotic cells, were carried to term, and BCKA decarboxylase activity was evident in the leukocytes.