Glutaric acidemia type I (GAI) (McKusick 231670) is an autosomal recessive disease affecting the catabolism of the amino acids lysine, hydroxylysine and tryptophan, caused by a defect in the gene encoding glutaryl-coenzyme A dehydrogenase (GCDH) and associated with severe neurological symptoms. Several pathogenic mutations in GCDH have been reported to cause GAI. One mutation, R402W, is more common than the others, which seem to be private" mutations. Here we report the entire sequences of introns 1, 2, 3, 6, 7, 8 and 9, and part of those of introns 4, 5 and 10 as well as 21 different mutations in 20 patients with GAI, corresponding to 38 out of 40 alleles.