RESUMO
We investigated the decline of activities of daily living with symptomatic progression in patients with mucopolysaccharidosis type II (MPS II) and investigated the associated factors. Clinical data were retrospectively collected from the medical records of 28 patients with MPS II who visited our hospital between October 2007 and August 2019. Activities of daily living were assessed over time using a 5-point scale (from stage 1, indicating independent, to stage 5, indicating total assistance + medical care); the relationships of the interval years from stage 2 (mild symptoms) to stage 4 (total assistance) with therapeutic intervention, anti-drug antibodies (ADA), urinary glycosaminoglycans (uGAG), and genotypes were analyzed. Eight are attenuated types, and 20 are severe types. Further, 20 underwent enzyme replacement therapy (ERT) alone, 5 underwent hematopoietic stem cell transplantation (HSCT) alone, and 3 underwent both therapy. The mean interval years (standard deviation) from stage 2 to 4 was 3.5 (0.7) and 7.3 (3.3) in patients who started undergoing ERT (n = 6) and HSCT (n = 3) at stage 2, respectively, whereas it was 3.1 (1.5) in patients who received no treatment until they reached stage 4 (n = 8). The study findings revealed the process of changes in the activities of daily living over a long duration in patients with MPS II undergoing different treatments. In severe type, the activity deteriorated regardless of the stage at which ERT was initiated. The activity declined slower in patients who received HSCT at an early stage.
RESUMO
Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is an X-linked recessive lysosomal storage disease caused by a mutation in the IDS gene and characterized by systemic accumulations of glycosaminoglycans. Its somatic symptoms can be relieved by enzyme replacement therapy (ERT) with idursulfase, but because the enzyme cannot cross the blood-brain-barrier (BBB), it does not address the progressive neurodegeneration and subsequent central nervous system (CNS) manifestations seen in patients with neuropathic MPS-II. However, pabinafusp alfa, a human iduronate-2-sulfatase (IDS) fused with a BBB-crossing anti-transferrin receptor antibody, has been shown to be efficacious against both the somatic and CNS symptoms of MPS II. We report two cases of MPS-II in Japanese siblings sharing the same G140V mutation in the IDS gene, who showed markedly contrasting developmental trajectories following enzyme replacement therapy (ERT). Sibling 1 was diagnosed at 2 years of age, started undergoing conventional ERT shortly afterward, and scored a developmental quotient (DQ) of 53 on the Kyoto Scale of Psychological Development (KSPD) at 4 years of age. Sibling 2 was diagnosed prenatally and received conventional ERT from the age of 1 month through 1 year and 11 months, when he switched to pabinafusp alpha. He attained a DQ of 104 at age 3 years and 11 months, along with significant declines in heparan sulfate concentrations in the cerebrospinal fluid. This marked difference in neurocognitive development highlights the importance of early initiation of ERT with a BBB-penetrating enzyme in patients with neuropathic MPS-II.
