Mucopolysaccharidosis type 3 (MPS3 / Sanfilippo syndrome MIM #252900) is an autosomal recessive lysosomal storage disorder caused by impaired degradation of heparan sulfate (found in the urine of affected patients). The syndrome is characterised by severe central nervous system degeneration, but only mild somatic disease (moderately severe claw hand and visceromegaly, little or no corneal clouding or skeletal change). Onset of clinical features usually occurs between 2 and 6 years; severe neurologic degeneration occurs in most patients between 6 and 10 years of age leading to a vegetative state, and death occurs typically during the second or third decade of life (primarily from aspiration pneumonia). Affected patients have a characteristic pattern of urine metabolites and a deficiency in one of the enzymes involved in heparan sulphate degradation; biochemical enzyme analysis utilises these features to confirm a clinical diagnosis. Type B is due to deficiency of the enzyme alpha-N-acetylglucosaminidase (NAGLU). There have been several recurrent mutations identified in the NAGLU gene although these are generally population specific.
Also known as
Sanfilippo syndrome type 3B, NAGLU deficiency, MPS
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Clinically affected patients should have their diagnosis confirmed by biochemical analysis (including disease subtype e.g. B); this should be arranged either locally or with the Enzyme Unit, Great Ormond Street Hospital. Such patients may then be referred for mutation analysis. If the necessary patient samples are unavailable genetic testing can be undertaken in the parents of the affected child.
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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
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