Hunter syndrome (MIM 309900) is an X-linked recessive lysosomal storage disorder. The condition is caused by a deficiency of the enzyme iduronate-2-sulphatase (IDS), which is required for the lysosomal degradation of the glycosaminoglycans, heparan sulphate and dermatan sulphate. Affected males have a characteristic pattern of urine metabolites and a deficiency of the IDS enzyme; biochemical enzyme analysis utilises these features to confirm a clinical diagnosis. Hunter syndrome is clinically heterogeneous, but the predominant clinical features include coarse facial features, stiff joints, hepatosplenomegaly, cardiovascular and respiratory disorders, developmental delay and mental retardation. The IDS gene consists of 9 exons and family specific mutations are found throughout the gene. Homologous recombination between the IDS gene and an adjacent unexpressed IDS pseudogene, located 20kb telomeric of IDS, leads to inversions and deletions, a common inversion accounts for ~10% of Hunter cases.
Also known as
Hunter syndrome, iduronate 2-sulphatase deficiency, IDS deficiency, MPS
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Clinically affected patients should have their diagnosis confirmed by biochemical analysis; such patients may then be referred for mutation analysis. If the necessary patient samples are unavailable genetic testing can be undertaken in the mother of the affected child. All confirmed Hunter patients (or their mothers if no sample is available from the affected male) are first tested for the presence of a common inversion, which has been shown to occur in ~10% of Hunter patients. Mutation screening is then undertaken in the remainder of the gene including MLPA analysis to detect large deletions and duplications.
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Great Ormond Street Hospital NE Thames Regional Genetics Service Laboratories
Great Ormond Street Hospital for Children
37 Queen Square
1ml EDTA neonates, 5ml EDTA adults
Deletion screen - 20 days; gene screen - 40 days
Disease / group
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Prenatals must be arranged in advance, through a Clinical Genetics department if possible. Amniotic fluid or CV samples should be sent to Cytogenetics for dissecting and culturing, with instructions to forward the sample to the Regional Molecular Genetics laboratory for analysis