Complementation analysis in lymphoid cells from five patients with different forms of maple syrup urine disease.

The possibility of genetic heterogeneity in maple syrup urine disease was investigated by measuring branched-chain ketoacid dehydrogenase in polyethylene glycol-induced heterokaryons of lymphoid cells. The lymphoid cell lines from five patients with varying forms of the disease were established after incubation with Epstein-Barr virus. The results suggested that there are at least two genetic complementation groups in the disease.