General description

Hypomyelination and congenital cataract), also known as hypomyelinating leukodystrophy 5 (HLD5), is a rare autosomal recessive disorder characterized by abnormal brain white matter development and congenital cataracts. Typically, cataracts are noticed within the first month of life. Early motor development, such as head control and sitting, is usually normal, but developmental delays become evident when independent walking is not achieved by the age of one. Most affected individuals acquire supported walking by around two years old, but they never develop independent walking. Over time, they experience progressive motor decline, eventually losing their ability to walk in adulthood.

This condition is associated with cerebellar ataxia, pyramidal tract signs, and abnormal reflexes, including reduced tendon reflexes. Muscle weakness and atrophy, particularly in the lower limbs, are common, along with peripheral neuropathy leading to decreased sensation in the arms and legs. Some individuals develop scoliosis, further impairing mobility. Additionally, people with this syndrome often have speech difficulties (dysarthria) and mild to moderate intellectual disabilities.