Glycogen storage disease type 1b (GSD1b) is an autosomal recessive inborn error of metabolism caused by deficiency of glucose-6-phosphate translocase (G6PT1). Current laboratory diagnosis for GSD1b is established by a functional enzyme assay of glucose-6-phosphatase in both fresh and detergent-treated liver homogenates. This procedure requires liver biopsy and is impractical for routine prenatal diagnosis owing to the high morbidity of fetal liver biopsy. Recently, the gene for GSD1b has been cloned and the prevalent mutations in different ethnic groups have been determined. In this study, prenatal molecular diagnosis was performed for a Chinese family in which a previous child was born homozygous for the G149E mutation. We detected genomic sequence variants by heteroduplex formation, followed by denaturing high performance liquid chromatography (DHPLC). With this method, post-PCR analysis was shortened to 7 min. In the case we analysed, PCR products amplified from the fetal DNA yielded a single peak in the chromatogram, indicating a homozygous state in the fetus. When wild-type PCR products were mixed with fetal PCR products, two peaks were observed, indicating that the fetus was homozygous for the parental (G149E) mutation. Sequencing results confirmed this diagnosis. As a result, the pregnancy was terminated and the diagnosis was confirmed on DNA analysis of the aborted fetus. We show here that DNA mutation analysis can be used in the prenatal diagnosis of GSD1b and that DHPLC promises to be a robust technique for this and other prenatal molecular diagnoses.
Copyright 2000 John Wiley & Sons, Ltd.