OBJECTIVETo carry out prenatal diagnosis for a glycogen storage disease type II (GSD II ) affected family.

METHODSThe acid-α -glucosidase (GAA) activity was measured in whole leukocytes and cultured amniocytes with 4-methylumbelliferyl-α -D-glucopyranoside as substrate and with acarbose as inhibitor. The coding regions of GAA gene were amplified by polymerase chain reaction and analyzed by direct DNA sequencing.

RESULTSThe proband and the fetus had low GAA activity (12.3% and 1.1% of the average normal range, respectively). Mutation analysis of the GAA gene revealed a novel nonsense mutation p.W738X and a reported nonsense mutation p.E888X in both the proband and the fetus; the reported pseudodeficiency allele c.[1726G to A: 2065G to A] was found in the proband, the mother and the fetus.

CONCLUSIONThe proband and the fetus were both GSD II affected. A combination of GAA activity analysis and mutation analysis is efficient for the prenatal diagnosis of GSD II. Mutation analysis should be a routine method in the prenatal diagnosis of GSD II in Asian population, where pseudodeficiency allele can cause low GAA activity in normal individuals which is relatively common in Asian.