Abstract: Objective To explore the clinical characteristics, imaging and genetic features of two brothers in a core family with Pelizaeus-Merzbache disease. Methods The clinical data of two brothers in a core family with Pelizaeus-Merzbache disease were retrospectively analyzed and followed up. Results Both the proband (male, 7 years old) and his younger brother ( 5 years old ) showed motor retardation since childhood, and so far they cannot stand and walk alone, but their intellectual development is basically unaffected. The brain magnetic resonance imaging (MRI) T 2 -weighted image showed diffuse hyperintensities in white matter. Both the proband and the younger brother had a hemizygous mutation of c. 259 delC in the proteolipid protein 1 gene. The proband’s mother was acarrier. Combined with family history, clinical manifestations and gene detection data, the type of the two brothers with Pelizaeus-Merzbache disease in a family was confimed. After 3 years followup, the motor function of both brothers was regressed. The proband can only stand with support for a short time, and the muscle strength of the limbs was grade III. the younger brother of the proband had deformed ankles and obviously talipes equinovarus， and cannot stand with support. In contrast, there was no obvious regression in their intelligence. Conclusion The two brothers had typical clinical features of Pelizaeus-Merzbache disease. With combination of clinical features and gene sequencing, they were diagnosed as Pelizaeus-Merzbache disease.

Key words: Pelizaeus-Merzbache disease; gene detection; proteolipid protein 1 gene