Glycogen storage disease type 1 (GSD 1)results from deficiency of the micro
somal multicomponent glucose-6-phosphatase system. Malfunction of the catal
ytic subunit characterises GSD la. GSD Ib and GSD Ic are characterised by d
efective microsomal glucose-6-phosphate or pyrophosphate/phosphate transpor
t, respectively. Recently, a gene encoding a microsomal transporter protein
has been found to be mutated in GSD Ib and Ic patients. Here, we report th
e genomic sequence of the transporter gene and the detection of a homozygou
s 2-bp deletion (1211delCT) and a homozygous donor splice site mutation (31
7+1G-->T) in two GSD Ic patients, confirming that GSD Ic is allelic to GSD
1b.