Mulibrey nanism is an extremely rare autosomal recessive genetic disorder characterized by profound growth delays and distinctive abnormalities of the muscles, liver, brain, and eyes. The acronym MULIBREY stands for (MU)scle, (LI)ver, (BR)ain, and (EY)e. Nanism is another word for dwarfism. A characteristic feature not included in the original acronym is the overgrowth of the fibrous sac that surrounds the heart restricting normal filling of the heart (constrictive pericarditis). Characteristic symptoms may include low birth weight, short stature, and severe progressive growth delays. Muscles are usually underdeveloped and lack normal tone (hypotonia). Some infants with this disorder may have an abnormally large liver (hepatomegaly). Infants typically have yellow discoloration in their eyes.