What Can We Learn from the Parents of Children Affected with Mucopolysaccharidosis Type III-A in Israel?

Sanfilippo Syndrome, or mucopolysaccharidosis type III (MPS III), is a group of autosomal-recessive lysosomal storage disorders leading to tissue accumulation of heparan sulfate. MPS III is caused by deficiency in one of 4 enzymes involved in lysosomal degradation of heparan sulfate. Based on the relevant enzyme deficiency, 4 types have been recognized. MPS III constitutes a progressive neurodegenerative and systemic disorder. Parents of children diagnosed with MPS III were interviewed using a retrospective questionnaire based on the known clinical manifestations of MPS III. Eight patients from 4 unrelated families of varied ethnic origin were included. All children were diagnosed with MPS type III-A. Average age at diagnosis was 6.1 years. The most common early clinical manifestations leading to parental suspicion of illness were speech delay and coarse facial features. All children were reported to have global developmental delay, sleep disorders, recurrent infections, hyperactivity, and decreased hearing. The time from first medical inquiry until diagnosis was over 2 years on average, consistent with the delay in diagnosis described in the literature. MPS III children frequently undergo early and repeated ear, nose and throat surgeries, thus we suggest that a high index of suspicion is warranted in relevant clinical circumstances.

Lysosomal storage diseases. Mucopolysaccharidosis type III, sanfilippo syndrome

The review describes the clinical, biochemical and molecular genetic characteristics of autosomal recessive mucopolysaccharidosis type III, or Sanfilippo syndrome. This is a genetically heterogeneous group of rare, but similar in nature, diseases caused by a deficiency of one of the four lysosomal enzymes involved in the degradation of heparan sulfate. All types of mucopolysaccharidosis III are characterized by severe degeneration of the central nervous system in combination with mild somatic manifestations, which is explained by the accumulation of high concentrations of heparan sulfate in the lysosomes of various cells, including the central nervous system. The primary biochemical defect in the most common type of mucopolysaccharidosis IIIA, occurring with a frequency of 1 : 105 and presented in 60% of all cases of the disease, is heparan-N-sulfatase, or sulfamidase deficiency. Mucopolysaccharidosis IIIB type occurs twice less often and accounts for about 30% of all cases of Sanfilippo syndrome. It is caused by the presence of inactivating mutations in the lysosomal -N-acetylglucosaminidase gene. Mucopolysaccharidosis IIIC and IIID are 4% and 6%, and occur at frequencies of 0.7 and 1.0 : 106. Mucopolysaccharidosis IIIC is caused by inactivating mutations in the gene of membrane-bound lysosomal acetyl-CoA:-glucosaminid-N-acetyltransferase, or N-acetyltransferase. Mucopolysaccharidosis IIID is based on the deficiency of lysosomal N-acetylglucosamine-6-sulfatase. The role of experimental models in the study of the biochemical basis of the pathogenesis of Sanfilippo syndrome and the development of various therapeutic approaches are discussed. The possibility of neonatal screening, early diagnosis, prevention and pathogenetic therapy of these severe lysosomal diseases are considered. As an example, a clinical case of diagnosis and treatment of a child with type IIIB mucopolysaccharidosis is presented.

Gastrointestinal Manifestations in Mucopolysaccharidosis Type III: Review of Death Certificates and the Literature

Background: Mucopolysaccharidosis type III (MPS III, Sanfilippo disease) is a life-limiting recessive lysosomal storage disorder caused by a deficiency in the enzymes involved in degrading glycosaminoglycan heparan sulfate. MPS III is characterized by progressive deterioration of the central nervous system. Respiratory tract infections have been reported as frequent and as the most common cause of death, but gastrointestinal (GI) manifestations have not been acknowledged as a cause of concern. The aim of this study was to determine the incidence of GI problems as a primary cause of death and to review GI symptoms reported in published studies. Methods: Causes of death from 221 UK death certificates (1957–2020) were reviewed and the literature was searched to ascertain reported GI symptoms. Results: GI manifestations were listed in 5.9% (n = 13) of death certificates. Median (IQR) age at death was 16.7 (5.3) years. Causes of death included GI failure, GI bleed, haemorrhagic pancreatitis, perforation due to gastrostomies, paralytic ileus and emaciation. Twenty-one GI conditions were reported in 30 studies, mostly related to functional GI disorders, including diarrhoea, dysphagia, constipation, faecal incontinence, abdominal pain/distension and cachexia. Conclusions: GI manifestations may be an under-recognized but important clinical feature of MPS III. Early recognition of GI symptoms and timely interventions is an important part of the management of MPS III patients.

Hip pathologies in mucopolysaccharidosis type III

Background Mucopolysaccharidosis type III (MPS III) comprises a group of rare lysosomal storage diseases. Although musculoskeletal symptoms are less pronounced than in other MPS subtypes, pathologies of hip and spine have been reported in MPS III patients. The purpose of this study was to describe hip pathologies and influencing parameters in MPS III patients. Methods A retrospective chart review was performed for 101 MPS III patients. Thirty-two patients met the inclusion criteria of enzymatically or genetically confirmed diagnosis and anteroposterior radiograph of the hips. Modified Ficat classification, Wiberg’s center-edge angle, and Reimer’s migration percentage were measured. Results The mean age at data assessment was 11.0 years (SD 5.7). Osteonecrosis of the femoral head was observed in 17/32 patients. No statistically significant association was found between these changes and age, sex, or MPS III subtype. Patients with a severe phenotype showed significantly higher rates of osteonecrosis (14/17) than patients with an intermediate phenotype. Hip dysplasia was present in 9/32 patients and was significantly associated with osteonecrosis of the femoral head (p = 0.04). Conclusions The present study demonstrates a high rate of hip pathologies in MPS III patients. Hip dysplasia and severe phenotype were significantly correlated with osteonecrosis of the femoral head. Therefore, radiographs of the hips are highly recommended in baseline and follow-up assessments of MPS III patients. Trial registration Retrospectively registered.