Introduction
Pelizaeus-Merzbacher Disease (PMD) is a rare X-linked recessive leukodystrophy caused by mutations in the proteolipid protein-1 (PLP1) gene on the Xq22.2 chromosome (1,2). The primary biological deficiency in affected patients with PMD is the failure of oligodendrocytes to properly myelinate axons, resulting in axonal degeneration and neurological dysfunction (1). More than 50% of cases are caused by duplication of a genomic region, including the entire PLP1 gene (2,3). PMD is characterized clinically by nystagmus, spastic quadriplegia, ataxia, and developmental delay (1). There is no definitive curative treatment. We report here a successful matched unrelated umbilical cord blood stem cell transplantation (UCBT) for PMD in a 2-year-old boy.