Glycogen storage disease (GSD) type Ib is an autosomal recessive disease caused by deficiency of glucose-6-phosphate translocase. We present here a five-month-old infant with GSD type Ib presented with neutropenia and classical features accompanied with hypercalcemia in the first and recurrent attacks. A homozygous mutation c1211_1212delCT in the G6PT (SLC37A4) gene confirmed the diagnosis. We suggest that hypercalcemia may be used as a new marker to demonstrate poor metabolic control in patients with GSD type Ib. GSD type I should be considered in the differential diagnosis of prolonged hypoglycemia in the newborn period.

Keywords: glikojen depo hastalığı tip Ib, hiperkalsemi, metabolik bozulma, nötropeni, hipoglisemi.