MTAP

The protein catalyzes the reversible phosphorylation of S-methyl-5'-thioadenosine to adenine and 5-methylthioribose-1-phosphate, functioning in polyamine metabolism and the methionine salvage pathway. Mutations cause diaphyseal medullary stenosis with malignant fibrous histiocytoma, inherited in an autosomal dominant pattern. The gene shows very low constraint against loss-of-function variants (pLI near zero), suggesting tolerance to such mutations in the general population.