Mucopolysaccharidosis IIIA


Mucopolysaccharidosis type III (MPS III, Sanfilippo syndrome) is an autosomal recessive mucopolysaccharide storage disorder caused by a deficiency of various lysosomal enzymes. MPS III encompasses a group of four lysosomal storage disorders resulting from a failure to break down the glycosaminoglycan heparan sulphate. Each of the four sub-types (A, B, C, & D) of MPS III is caused by the deficiency of a different enzyme in the degradative pathway of heparan sulphate. MPS IIIA (Sanfilippo A Syndrome OMIM 252900) is caused by a deficiency of the enzyme heparan-N-sulphatase (Sulphamidase), which results in the accumulation of heparan sulphates in the lysosome. MPS IIIA is a multisystemic disorder, clinical symptoms of which usually occur after about 2 years of apparently normal development. These symptoms include hyperactivity, aggressive behaviour, delayed speech development, sleep disturbances, coarse hair, hirsutism and diarrhoea which are then followed by progressive mental retardation around 6 to 10 years of age resulting in death usually between the second and third decade of life. Type A has been reported to be the most severe, with earlier onset and rapid progression of symptoms and shorter survival. The gene for sulphamidase or N-sulphoglucosamine sulphohydrolase ( SGSH) resides on chromosome 17q25.3 spanning 11 kb and comprising 8 exons encoding a 502 amino acid precursor protein that is processed to a 482 amino acid glycoprotein that is active as a homodimer.

Referral information

This service is funded by the National Commissioning Group (NCG). Samples received from England, Northern Ireland and Scotland are charged to NCG with the majority of samples being received from The Willink Metabolic Unit. New patients are initially diagnosed by enzyme analysis, therefore patients will usually have already been referred to a relevant NCG centre before DNA analysis is requested. Funding from the NCG also covers carrier detection, by DNA analysis, for family members.

Price & reporting times

Test Price NHS (£) Price non- NHS (£ ) TRT (calendar days)
Mutation scanning POA POA 56
Single mutation test POA POA 28
Urgent/Predictive single mutation test POA POA 14

Test validation & quality assurance - information for users

The laboratory is UKAS assessed against ISO 15189 standards.

Sample requirements

4ml EDTA blood sample. If Willink laboratory testing is required, a 10ml urine sample is required

Referral guidelines

Please see our referral guidelines for more information.

OMIM Number(s) - 252900

Gene(s) - SGSH