label: chromosome Xp11.23-p11.22 duplication syndrome
label_lc: chromosome xp11.23-p11.22 duplication syndrome
description: A form of methylmalonic acidemia with homocystinuria (see this term), an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, lethargy, failure to thrive, developmental delay, intellectual deficit and seizures.