Five-year follow-up of two siblings with aspartylglucosaminuria undergoing allogeneic stem-cell transplantation from unrelated donors

Aspartylglucosaminuria is a rare, inherited lysosomal disease characterized by a slowly progressive mental retardation and coarse facial and body features. With the intent to provide the deficient enzyme aspartylglucosaminidase, allogeneic stem-cell transplantation (ASCT) has been attempted. Only a few cases of transplants have been reported. Two siblings with aspartylglucosaminuria underwent allogeneic bone marrow transplants using unrelated human leukocyte antigen-A, -B, and DR identical donors at ages 10 years 5 months and 5 years 10 months, respectively. They were followed during 5 years with biochemical, neuroradiologic, neuropsychologic, and clinical investigations. During 5 years follow-up, no neuropsychologic or clinical deterioration was noted in the children. A stable expression of aspartylglucosaminidase was found during the whole follow-up period. The spinal fluid concentration of Tau-protein, a marker of neuronal and axonal degeneration and damage, peaked at approximately 12 months after bone-marrow transplantation and then declined to almost normal levels after 5 years. By magnetic resonance imaging (MRI), an improvement of myelination in the youngest sibling and an arrest of demyelination in the older one were observed. The importance of long-term follow-up of children after ASCT in this rare, very slowly progressive lysosomal disease must be emphasized. We report that none of the children had lost any capabilities since the transplantation; moreover, an improvement is shown in biochemical markers and MRI white-matter signals, suggesting a beneficial effect.