Glycogen storage disease type Ia (GSD Ia) is an autosomal recessive disorder caused by mutations in the G6PC gene encoding glucose-6-phosphatase (G6Pase), a key enzyme for the maintenance of glucose homeostasis. Molecular analysis is a reliable and accurate way of diagnosing GSD Ia without to need for invasive liver biopsies for enzyme tests. In some ethnic groups and geographic regions, allelic homogeneity was detected in GSD Ia. In the present study, the most common 12 mutations in the world were searched by microelectronic array technology, a new method, in 27 Turkish patients diagnosed for GSD Ia and the relation between detected mutations and clinical and laboratory findings was investigated. Mutations causing the disease were detected in 45 (83.3%) of 54 alleles screened in the cases with GSD Ia. Allelic frequency of mutations (p.R83C, p.G270V, p.G188R, p.W77R) looked for were found as 68.5%, 7.4%, 3.7%, and 3.7%, respectively. p.G188R mutation was detected for the first time in a patient of Turkish origin. Eight (p.R170Q p.Q347X, c.79delC, c.380_381insTA, p.D38V, p.W63X, c.648G>T, c.979_981delTTC) of 12 mutations looked for were coincided in none of the patients. The patient with homozygous p.W77R mutation seemed to present milder clinical and laboratory findings, compared to other patients. In conclusion, we suggest that microarray technology, which allows rapid analysis of frequently detected mutations and has considerably lower costs than other methods, can be successfully used in diagnosis of GSD Ia in populations with allelic homogeneity, such as patients of Turkish origin, instead of screening the whole gene. (C) 2013 Elsevier B.V. All rights reserved.