Among all four subtypes of Sanfilippo syndrome (also called mucopolysaccharidosis type III, or MPS III), Sanfilippo type B is the most frequent subtype among the Taiwanese population, according to a retrospective study.
These findings are essential for the early diagnosis and timely management of this disorder, as well as the development of future therapies
The study, “Mucopolysaccharidosis III in Taiwan: Natural history, clinical and molecular characteristics of 28 patients diagnosed during a 21-year period,” was published in the American Journal of Medical Genetics.
The four subtypes of Sanfilippo syndrome (types A, B, C, D) are caused by a deficiency in different enzymes. However, all are involved in the degradation of a large molecule called heparan sulfate, which leads to the accumulation of toxic waste material inside cellular structures called lysosomes.
The incidence of Sanfilippo syndrome differs among various populations. Incidence in the Netherlands has been reported for 1 in 53,000 live births, while in Taiwan the numbers change to 1 in 255,000 live births.
Although the natural course of the disease in Caucasian populations has been described in several reports, there is limited information about the disease course among Asians, including the Taiwanese.
A team of Taiwanese researchers conducted a retrospective study of patients who had been diagnosed with Sanfilippo syndrome between 1996 and 2017. In total, 28 patients were included in the study — three with type A, 24 with type B, and one with type C.
Patient information including laboratory results, medical history, clinical features, and physical examinations were collected and analysed.
The median age at confirmed diagnosis among these patients was 4.6. Hyperactivity was a common initial symptom, while intellectual disability, hyperactivity, coarse facial features, and hepatosplenomegaly (swelling of the liver and spleen) were among the most common clinical features.
Epilepsy occurred in 10 patients, with a median age at first seizure of 11.
Overall, this study revealed that Taiwanese patients with Sanfilippo syndrome manifest a broad spectrum of disease phenotypes, from mild to severe, indicating the clinical heterogeneity of the disease.
These included neurological, respiratory, cardiovascular, auditory, visceral, and skeletal systems.
“Consequently, a multidisciplinary approach to patient management is required once the diagnosis is made,” researchers wrote.
“Accurate knowledge of the natural course of the disease will help assess disease progression and therapeutic effects, as well as evaluate clinical and biomarker endpoints for clinical trials,” they concluded.