Bone marrow transplantation in metachromatic leukodystrophy caused by saposin-B deficiency: a case report with a 3-year follow-up period.

A 2-year-old child had a metachromatic leukodystrophy-variant phenotype mainly involving the peripheral nervous system (PNS) that was caused by saposin-B deficiency. Bone marrow transplantation resulted in transient deterioration then continuous improvement of PNS functions. These findings were supported by nerve conduction velocity measurements, but the symptoms ultimately worsened. Magnetic resonance imaging showed persistent white matter lesions and progressive pontocerebellar atrophy.