Succinic semialdehyde dehydrogenase deficiency (SSADH-D) in an eleven-month-old infant with marked hypotonia and staring episodes: a case report

Summary Introduction Succinic semialdehyde dehydrogenase deficiency (SSADH), also known as 4-hydroxybutyric aciduria (OMIM #271980, 610045), is an ultra-rare neurometabolic disorder inherited in an autosomal recessive pattern. It is usually characterised by a relatively nonprogressive encephalopathy in the first two years of life with hypotonia and developmental delay, associated with mild ataxia and hyporeflexia, as well as delays in language and speech development. Case report We report on a case of a four-year-old girl with SSADH deficiency who presented, at the age of 11 months old, with marked hypotonia, global neurodevelopmental delay and epilepsy. The diagnosis of “Succinic semialdehyde dehydrogenase deficiency” was indicated as there was a marked elevation of the levels of 4-hydroxy-butyric and 3,4-dihydroxybutyric acid caused by mutation at the gene ALDH5A1 in the homozygous state, identified with WES technique. Currently, she is four years old and has a severe global psychomotor delay, excessive hypotonia, hyperextensibility, and ataxia and is free of seizures. Conclusion At the early stage of clinical presentation, the condition is difficult to differentiate from other encephalopathies. This case report suggests that analysis of urinary organic acids should be performed in all patients at risk to allow early diagnosis. DNA analysis with the WES technique can confirm the diagnosis.