Abstract
Hunter syndrome, or mucopolysaccharidosis type 2 (MPS2), is a lysosomal storage disorder associated with the involvement of multiple organs such as the central nervous system, hepatomegaly, musculoskeletal, respiratory, cardiac, and hearing. This is due to the accumulation of glycosaminoglycans in body tissues leading to organ failure. Since the laboratories in Kenya do not screen for metabolic diseases, there is the likelihood of assumption that these patients do not exist. These first cases were referred from the eastern part of Kenya where the majority of inhabitants are from the same ethnic community. It was noted that there was increased mortality among boys below the age of 20 years, and hence, the families sought for help in the national referral and teaching hospital. The case series is meant to show that these cases exist and the majority of the patients may be dying before the diagnosis is made. There are no data on MPS2 from Kenya, and the prevalence and incidence are unknown. In this retrospective study, we present a case series of 6 Kenyan boys with MPS2 from a national referral hospital. They were part of 17 patients who had had their blood analyzed for metabolic diseases. All of them were symptomatic with varying degrees of central nervous system involvement. They had undetectable levels of iduronate-2-sulfatase (I2S) enzyme, and three genetic mutations were detected in the IDS gene.
Highlights
Mucopolysaccharidosis type II (Hunter syndrome or mucopolysaccharidosis type 2 (MPS2)) is an X-linked disorder caused by a deficiency in the lysosomal enzyme iduronate-2-sulfatase (I2S) leading to the accumulation of glycosaminoglycans (GAGs), dermatan sulfate and heparan sulfate
We present 6 confirmed cases of MPS2 and describe the clinical characteristics. is preliminary analysis will aid in informing Kenyan healthcare professionals on the presence of MPS2 patients among patients who report having had male relatives who died of similar illness without a diagnosis
Out of the total of 17 children that were reviewed, 6/17 (35.3%) patients had pathogenic variants in the IDS gene associated with X-linked recessive mucopolysaccharidosis type II. ey were all symptomatic with mainly neurological, musculoskeletal, and respiratory symptoms. e mean age at diagnosis was 7.5 years with a range of 3–13 years. e guardians noted the first early symptoms at an average age of three years. e six patients were from a total of four families with some being siblings
Summary
Mucopolysaccharidosis type II (Hunter syndrome or MPS2) is an X-linked disorder caused by a deficiency in the lysosomal enzyme iduronate-2-sulfatase (I2S) leading to the accumulation of glycosaminoglycans (GAGs), dermatan sulfate and heparan sulfate. Erefore, with a paucity of data on MPS2 in the majority of these countries, most of the patients with severe Hunter syndrome die early before the diagnosis is made. E boy had a missense type of mutation with a severe type of MPS2 He developed the symptoms of nocturnal snoring by age 4 years and progressively had regression of milestones, and by the age of ten years, he was deaf, could only mumble some things, was hyperactive, and could not follow any instructions. He had a severe form of MPS2 with a similar mutation as in case 1 He started snoring while asleep at the age of 3 years. Ough the enzyme activity for the three patients was the same, the first born had a severe form of the disease with deafness and poor cognitive function. A maternal uncle had died at 20 years with similar illness
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