The group of inherited metabolic disorders (IMD) comprises more than 1000 diseases, in which the deficient enzyme activity is the most common cause.The autosomal recessive pattern of inheritance is the most freuqent, the maternal inheritance is also possible in case of some mitochondrial disorders. The clinical severity depends on the type of molecular defect and residual enzyme activity.
First clinical signs may appear already in early childhood, however some IMD may manifest later, even in late adulthood. The early manifestation usually predicts more severe systemic disease with poor prognosis.
The latter forms are oligosymptomatic often accompanied by psychiatric symptoms.