Author Affiliations: Department of Pediatrics, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China (Li XY, Shi XY, Ju J, Yang XF, Zou LP); Department of Pediatrics, First Affiliated Hospital of Chinese PLA General Hospital, 51 Fucheng Street, Beijing 100037, China (Hu XH)

Corresponding Author: Li-Ping Zou, Department of Pediatrics, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China (Tel: +86 10 55499016; Fax: +86 10 55499016; Email: zouliping21@hotmail.com)

doi: 10.1007/s12519-012-0357-1

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.

Key words: iduronate 2-sulfatase gene; mucopolysaccharidosis II; mutation

World J Pediatr 2012;8(3):281-283