Mulibrey nanism is a rare 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. Signs and symptoms of the disorder may include constrictive pericarditis; low birth weight; short stature; severe progressive growth delays; hypotonia; hepatomegaly; and yellow discoloration of the eyes in infancy. It is caused by mutations in the TRIM37 gene and is inherited in an autosomal recessive manner. Treatment may include surgery for constrictive pericarditis, medications for progressive heart failure and hormone replacement therapy.

Individuals with MN typically have a high-pitched voice. Other symptoms may include abnormally prominent veins in the neck, congestion in the lungs, abnormal fluid accumulation in the abdomen (ascites), swelling of the arms and/or legs (peripheral edema), and/or enlargement of the heart (cardiac hypertrophy) and/or liver (hepatomegaly). There may also be elevated pressure in the veins, congestion or blockage in the main artery serving the lungs (pulmonary artery), and/or a build-up of fibrous tissue in the walls of the lungs (pulmonary fibrosis). Associated complications of these conditions may lead to congestive heart failure.

In some cases, individuals with mulibrey nanism may have additional physical abnormalities, such as an unusually thin shinbone (fibrous tibia dysplasia). Large cerebral ventricles in the brain and delayed motor development are uncommon findings. Most affected individuals have normal intelligence. Individuals with mulibrey nanism often have underdevelopment of various endocrine glands, that leads to hormone deficiencies. Delayed puberty sometimes occurs, accompanied by infrequent or very light menstrual periods. Females have an increased risk for premature ovarian failure and ovarian tumors.

Differences in the nature and severity of the wide range of abnormalities and complications make it difficult to predict the course of the disorder in any one individual. Some individuals may be more mildly affected, while others experience severe complications. Episodes of respiratory failure induced by an infection, as well as congestive heart failure, have occurred in infants (in addition to older individuals) with the disorder and may cause early death. It has been suggested that constrictive pericarditis with restrictive cardiomyopathy, when present, plays a large part in the prognosis. Because the heart involvement is critical for the prognosis, early diagnosis is usually of major importance.