General description

Pelizaeus-Merzbacher-like disease (PMLD), also known as hypomyelinating leukodystrophy 2 (HLD2), is distinguished from Pelizaeus-Merzbacher disease (PMD, HLD1) by the absence of pathogenic variants in the PLP1 gene, despite exhibiting clinically indistinguishable symptoms. Some cases of PMLD are caused by pathogenic variants in the GJC2 gene and are classified as PMLD1. PMLD follows an autosomal recessive inheritance pattern and can affect both males and females.

Typical cases present with nystagmus in early infancy, delayed motor development by the age of one, cerebellar ataxia by four, and spasticity by six. Compared to PMD, PMLD generally allows for better motor development, with about one-third of cases achieving independent walking. However, regression often begins during adolescence.