A novel iduronate 2-sulfatase mutation in a Chinese family with mucopolysaccharidosis type II.

BACKGROUND

Mucopolysaccharidosis type II (MPS II; also known as Hunter syndrome) is an X-linked multisystem disorder resulting from the defective activity of the enzyme iduronate-2-sulfatase (IDS). Genetic testing is crucial in clarifying and diagnosing different types of MPS diseases. In this paper we report a novel IDS nonsense mutation resulting in MPS II in several patients from a Chinese family.

METHODS

IDS enzyme activity, polymerase chain reaction, and DNA sequencing were performed to confirm the diagnosis of MPS II.

RESULTS

Three patients had no detectable IDS activity. Two genetic tests revealed a novel IDS nonsense mutation (c.1030G>T, p.E344X) inherited from their mothers. The nonsense mutation shortened the peptide chain from 550 to 344 amino acids, which is believed to be a disease-causing mutation.

CONCLUSIONS

MPS II is inherited in an X-linked manner. The risk to sibs depends on the carrier status of the mother. Genetic testing is necessary to identify disease-causing mutation. With this information, carrier testing for at-risk female relatives and prenatal testing for pregnancies at increased risk become possible.