Distinct from non-syndromic POI, pleiotropic Mendelian disorders, including fragile X syndrome: familial mental retardation 1 (FMR1); (Xq27.3), blepharophimosis-ptosis-epicanthus syndrome (BPES): forkhead box L2 (FOXL2) (3q23); galactosemia: galactose-1-phosphate uridyl transferase (GALT) (9p13); carbohydrate-deficient glycoprotein syndrome type 1: phosphomannomutase 2 (PMM2) (16p13), may manifest POI as part of their phenotypic spectrum [4]. The gene discussed is PMM2; the disease is classic galactosemia.