Clinical, biochemical and molecular findings of 24 Brazilian patients with glutaric acidemia type 1: 4 novel mutations in the GCDH gene

Glutaric aciduria type 1 (GA-1) is a rare but treatable inherited disease caused by deficiency of glutaryl-CoA dehydrogenase activity due to GCDH gene mutations. In this study, we report 24 symptomatic GA-1 Brazilian patients, and present their clinical, biochemical, and molecular findings. Patients were diagnosed by high levels of glutaric and/or 3-hydroxyglutaric and glutarylcarnitine. Diagnosis was confirmed by genetic analysis. Most patients had the early-onset severe form of the disease and the main features were neurological deterioration, seizures and dystonia, usually following an episode of metabolic decompensation. Despite the early symptomatology, diagnosis took a long time for most patients. We identified 13 variants in the GCDH gene, four of them were novel: c.91 + 5G > A, c.167T > G, c.257C > T, and c.10A > T. The most common mutation was c.1204C > T (p.R402W). Surprisingly, the second most frequent mutation was the new mutation c.91 + 5G > A (IVS1 ds G-A + 5). Our results allowed a complete characterization of the GA-1 Brazilian patients. Besides, they expand the mutational spectrum of GA-1, with the description of four new mutations. This work reinforces the importance of awareness of GA-1 among doctors in order to allow early diagnosis and treatment in countries like Brazil where the disease has not been included in newborn screening programs.

Molecular and biochemical study of glutaric aciduria type 1 in 49 Russian families: nine novel mutations in the GCDH gene

Glutaric aciduria type 1 (GA1, deficiency of glutaryl CoA dehydrogenase, glutaric acidemia type 1) (ICD-10 code: E72.3; MIM 231670) is an autosomal recessive disease caused by mutations in the gene encoding the enzyme glutaryl CoA dehydrogenase (GCDH). Herein, we present the biochemical and molecular genetic characteristics of 51 patients diagnosed with GA1 from 49 unrelated families in Russia. We identified a total of 21 variants, 9 of which were novel: c.127 + 1G > T, с.471_473delCGA, c.161 T > C (p.Leu54Pro), c.531C > A (р.Phe177Leu), c.647C > T (p.Ser216Leu), c.705G > A (р.Gly235Asp), c.898 G > A (р.Gly300Ser), c.1205G > C (р.Arg402Pro), c.1178G > A (р.Gly393Glu). The most commonly detected missense variants were c.1204C > T (p.Arg402Trp) and с.1262C > T (р.Ala421Val), which were identified in 56.38% and 11.7% of mutated alleles. A heterozygous microdeletion of the short arm (p) of chromosome 19 from position 12,994,984-13,003,217 (8233 b.p.) and from position 12,991,506-13,003,217 (11,711 b.p.) were detected in two patients. Genes located in the area of imbalance were KLF1, DNASE2, and GCDH. Patients presented typical GA1 biochemical changes in the biological fluids, except one patient with the homozygous mutation p.Val400Met. No correlation was found between the GCDH genotype and glutaric acid (GA) concentration in the cohort of our patients.