We describe a Chinese patient with glycogen storage disease type 1b presenting with failure to thrive and protuberant abdomen. The neutropenia was mild and the patient did not have fasting hypoglycemia. Direct DNA sequencing of the G6PT1 gene revealed the patient to be a compound heterozygote of a novel missense mutation, Y24H, and another missense mutation, P191L, which we had described previously. The mother is heterozygous for the Y24H mutation and the father is heterozygous for the P191L mutation. Y24H and P191L may be ethnic-specific mutations as they have not been reported in other populations. The DNA-based diagnosis of GSD 1b will enable us to make an accurate determination of carrier status and to perform prenatal diagnosis of this disease.