Abstract: Objective　To explore the clinical characteristics, gene mutation and pathogenesis of succinic semialdehyde dehydrogenase deficiency (SSADHD) caused by ALDH5A1 gene mutation. Method　The clinical data and gene sequencing results of SSADHD in a child were retrospectively analyzed, and the related literature was reviewed. Results　A 3-year- and 6-month-old girl presented with recurrent episodes of paroxysmal dystonia. However, the brain magnetic resonance imaging, video electroencephalogram, blood biochemical examination and hematuria genetic metabolism screening all found no abnormalities. Gene sequencing showed that there were two heterozygous mutations in the exon region of ALDH5A1 gene, c.112G > A (p.A38T) (pathogenicity is not yet clear) and c.1529C > T (p.S510F) (reported pathogenic mutation). The two heterozygous mutations were derived from their parents respectively, which were complex heterozygous mutations and consistent with autosomal recessive inheritance. Therefore, the child was diagnosed with SSADHD caused by ALDH5A1 gene mutation. A total of 26 related literatures were retrieved, and 75 ALDH5A1 gene mutations located in Exon1~Exon11 were reported, including missense mutations, deletion mutations, insertion mutations, splicing mutations and nonsense mutations. Conclusion　ALDH5A1 gene mutation is closely related to SSADHD, and gene detection is helpful for the diagnosis of SSADHD.

Key words: succinic semialdehyde dehydrogenase deficiency;　ALDH5A1 gene mutation;　child