Mucopolysaccharidosis III in Taiwan: Natural history, clinical and molecular characteristics of 28 patients diagnosed during a 21-year period

Abstract

Mucopolysaccharidosis type III (MPS III, Sanfilippo syndrome) has a variable age of onset and variable rate of progression. However, information regarding the natural history of this disorder in Asian populations is limited. A retrospective analysis was carried out for 28 patients with MPS III (types IIIA [n=3], IIIB [n=23], and IIIC [n=2]; 15 males and 13 females; median age, 8.2 years; age range, 2.7-26.5 years) seen in six medical centers in Taiwan from January 1996 through October 2017. The median age at confirmed diagnosis was 4.6 years. The most common initial symptom was speech delay (75%), followed by hirsutism (64%) and hyperactivity (54%). Both z scores for height and weight were negatively correlated with age (r=-.693 and -0.718, respectively; p<.01). The most prevalent clinical manifestations were speech delay (100%) and intellectual disability (100%), followed by hirsutism (93%), hyperactivity (79%), coarse facial features (68%), sleep disorders (61%), and hepatosplenomegaly (61%). Ten patients (36%) had epilepsy, and the median age at the first seizure was 11 years. Thirteen patients (46%) experienced at least one surgical procedure. At the time of the present study, 7 of the 28 patients had passed away at the median age of 13.0 years. Molecular studies showed an allelic heterogeneity without clear genotype and phenotype correlations. MPS IIIB is the most frequent subtype among MPS III in the Taiwanese population. An understanding of the natural history of MPS III may allow early diagnosis and timely management of the disease facilitating better treatment outcomes.