A T-TO-A SUBSTITUTION IN THE E1-ALPHA SUBUNIT GENE OF THE BRANCHED-CHAIN ALPHA-KETOACID DEHYDROGENASE COMPLEX IN 2 CELL-LINES DERIVED FROM MENONITE MAPLE SYRUP URINE DISEASE PATIENTS

We cloned and sequenced cDNAs of the E1α and E1β subunits of the branched chain α-ketoacid dehydrogenase complex (BCKDH) in two cell lines derived from two different Menonite MSUD patients (GM 1655, GM 1099). A T-to-A substitution which generates an asparagine in place of a tyrosine at amino acid 394 of the mature E1α subunit was present in both alleles in these two cell lines, whereas cDNAs of the E1β subunit in these cell lines were identical to that of normal human lymphoid cell line and that of the clone from a human placenta cDNA library. It is suggested that the Menonite MSUD is caused by the missense mutation of the E1α subunit of the BCKDH complex. © 1990.