PMM2 and congenital disorder of glycosylation: The clinical signs of PMM2 (phosphomannomutase‐2)‐CDG, the most common type of CDG, include psychomotor retardation with cerebellar hypoplasia, an abnormal fat distribution, inverted nipples, strabismus, hypotonia, failure to thrive, liver dysfunction, blood coagulation abnormalities, and cardiac and renal involvement.