Low prevalence of glucokinase gene mutations in gestational diabetic patients with good glycemic control.

Glucokinase (GCK) plays a key role in glucose homeostasis. Gestational diabetes mellitus increases the risk of gestational complications in pregnant women and fetuses. We screened for mutations in coding and flanking regions of the GCK gene in pregnant women with or without gestational diabetes in a Brazilian population. A sample of 200 pregnant women classified as healthy (control, N = 100) or with gestational diabetes (N = 100) was analyzed for mutations in the GCK gene. All gestational diabetes mellitus patients had good glycemic control maintained by diet alone and no complications during pregnancy. Mutations were detected by single-strand conformation polymorphism and DNA sequencing. Thirteen of the 200 subjects had GCK gene mutations. The mutations detected were in intron 3 (c.43331A>G, new), intron 6 (c.47702T>C, rs2268574), intron 9 (c.48935C>T, rs2908274), and exon 10 (c.49620G>A, rs13306388). None of these GCK mutations were found to be significantly associated with gestational diabetes mellitus. In summary, we report a low frequency of GCK mutations in a pregnant Brazilian population and describe a new intronic variation (c.43331A>G, intron 3). We conclude that mutations in GCK introns and in non-translatable regions of the GCK gene do not affect glycemic control and are not correlated with gestational diabetes mellitus.

The functional polymorphisms -429T>C and -374T>A of the RAGE gene promoter are not associated with gestational diabetes in Euro-Brazilians.

The receptor for advanced glycation end products (RAGE or AGER) is a multiligand member of the immunoglobulin superfamily. RAGE is expressed in several tissues, including human myometrium, chorionic villi and placenta. Advanced glycation end products are the best studied ligands of RAGE; they have pro-inflammatory actions in human gestational tissues, increasing oxidative stress and the release of cytokines and prostaglandins. We investigated the association of RAGE gene promoter polymorphisms -429T>C (rs1800625) and -374T>A (rs1800624) with gestational diabetes. A sample of 750 unrelated European origin pregnant Brazilian women were classified as nondiabetic (control group, N = 600) or having gestational diabetes (N = 150) according to American Diabetes Association 2009 criteria. Genotyping was performed by PCR-RFLP. The frequencies of the rare alleles -429C (6.3 versus 9.1%) and -374A (26 versus 30%) were not significantly different between the gestational diabetes patients and healthy pregnant women. Also, the -429T>C and -374T>A polymorphisms were not associated with body mass index, lipid profile, fasting glycemia, HbA1C, or insulin requirement. We found that functional promoter polymorphisms of the RAGE gene were not associated with gestational diabetes or its complications in these Euro-Brazilian patients.