Introduction: S-adenosylhomocysteine hydrolase (SAHH) is one of the enzymes involved in converting methionine to homocysteine with transmethylation processes. Methyltransfer reactions are impaired in SAHH deficiency. SAHH deficiency is multisystemic and antenatal onset disorder. It is also ultra rare disease. Only 19 cases have been reported so far. Case Presentation: We report an eighteen-month-old female patient who was investigated due to elevated transaminase levels, coagulopathy, cataract, hypotonia, and global developmental delay. She also had dysmorphic findings. Significant methionine elevation and mild homocysteine elevation were detected. Other metabolic investigations and laboratory findings were unremarkable. Homozygous novel variant in the AHCY gene and heterozygous novel variant in the PITX3 gene were found by whole-exome sequencing (WES) analysis. Methionine restricted diet, phosphatidylcholine, and creatine supplements were advised. Conclusion: In this report, a case with a novel variant in the AHCY gene and prominent dysmorphic findings was reported. More SAHH deficiency cases with different findings and phenotypes will be revealed through the use of WES and genetic panels.

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