MED13L syndrome

MED13L syndrome is a developmental disorder characterized by developmental delay, intellectual disability, and minor differences in facial features. Additionally, some people with this condition have recurrent seizures (epilepsy) or heart abnormalities that are present from birth (congenital heart defects).

Intellectual disability and developmental delay are usually moderate to severe in people with MED13L syndrome. Weak muscle tone (hypotonia) and delayed development of motor skills, such as sitting, standing, and walking, are early symptoms of the condition. After learning to walk, some affected individuals continue to have difficulty with coordination and balance (ataxia). Speech is also delayed, and most people with this condition develop only a few words or never learn to talk. People with MED13L syndrome may exhibit characteristics typical of autism spectrum disorder, including repetitive actions and difficulty with social interactions.

Most people with MED13L syndrome have unusual facial features that consist of a depressed nasal bridge, a bulbous nasal tip, straight eyebrows, outside corners of the eyes that point upward (upslanting palpebral fissures), full cheeks, and an open mouth. Other facial features that sometimes occur are a pronounced double curve of the upper lip (Cupid's bow), and a deep space between the nose and upper lip (philtrum).

Different congenital heart defects can occur in MED13L syndrome. Affected individuals may have transposition of the great arteries, which is abnormal positioning of the large blood vessel that distributes blood from the heart to the rest of the body (aorta) and the artery that carries blood from the heart to the lungs (the pulmonary artery). Other congenital heart defects in MED13L syndrome include a hole between the two lower chambers of the heart (ventricular septal defect), a hole between the two upper chambers of the heart (patent foramen ovale), or a particular combination of heart defects known as tetralogy of Fallot.