Molecular diagnosis of type 1c glycogen storage disease

Glycogen storage disease type 1 (GSD 1)results from deficiency of the microsomal multicomponent glucose-6-phosphatase system. Malfunction of the catalytic subunit characterises GSD la. GSD Ib and GSD Ic are characterised by defective microsomal glucose-6-phosphate or pyrophosphate/phosphate transport, respectively. Recently, a gene encoding a microsomal transporter protein has been found to be mutated in GSD Ib and Ic patients. Here, we report the genomic sequence of the transporter gene and the detection of a homozygous 2-bp deletion (1211delCT) and a homozygous donor splice site mutation (317+1G-->T) in two GSD Ic patients, confirming that GSD Ic is allelic to GSD 1b.