2 MISSENSE POINT MUTATIONS IN DIFFERENT ALLELES IN THE 3-HYDROXY-3-METHYLGLUTARYL COENZYME-A LYASE GENE PRODUCE 3-HYDROXY-3-METHYLGLUTARIC ACIDURIA IN A FRENCH PATIENT

Two novel point mutations in the 3-hydroxy-3methylglutaryl coenzyme A lyase gene were found in a French patient with double heterozygous 3-h ydroxy-3-methylglutaric aciduria. Amplification by reverse transcripta se-polymerase chain reaction of the mRNA using five different pairs of oligonucleotides produced no differences in the fragments amplified w ith respect to the control. Single-strand conformation polymorphism an alysis showed that only one amplified fragment was different in the pa tient vs, control. Sequencing of the amplified fragments showed two mi ssense point mutations, A698G and T788C, each of them mixed with the w ild-type sequence. These mutations produced the changes H233R and L263 P, leading to changes in the enzyme activity, which was largely abolis hed. The father and one brother of the proband were heterozygous for t he L263P mutation and the mother and one daughter were heterozygous fo r the H233R mutation, which confirms the double-heterozygous character of the patient. Another sibling was free of the mutations. An enzymat ic restriction analysis has been proposed to screen the occurrence of these two mutations in future patients. (C) 1998 Academic Press.