Microsatellite polymorphisms at the glucokinase locus: a population association study in Caucasian type 2 diabetic subjects

Genetics of type 2 diabetes mellitus and obesity--a review

Type 2 diabetes (T2D) and obesity are recognized as conditions of growing biomedical importance to societies worldwide. Despite this, lack of understanding concerning the processes which normally serve to maintain weight and to regulate glucose concentrations, and ignorance about the mechanisms by which these homeostatic processes fail, remains a significant obstacle to the development of improved tools for management and prevention. There has been a long-standing belief that the identification of the specific genes influencing development of these conditions has the potential to reveal these fundamental processes, thereby providing vital clues to support clinical advances. Furthermore, there has been the hope that this information will translate into the capacity to deliver more 'personalized' medical care, whereby management can be tailored in accordance with an appreciation of individual molecular pathogenesis. As this review indicates, these developments are already a reality for selected monogenic forms of diabetes and obesity. Recent advances in the identification of genes underlying multifactorial forms of these conditions will accelerate efforts to effect similar clinical translation across the full spectrum of disease.

The search for type 2 diabetes genes

Type 2 diabetes (T2DM) is a serious disease with severe complications. Around one in 10 people alive today suffer from type 2 diabetes or are destined to develop it before they die. Inheritance plays an important role in the cause of type 2 diabetes. A considerable amount of research is devoted to defining the genes involved in the aetiology of this widespread disease. This information is crucial if we are to improve our methods of preventing and treating diabetes. Over the last 25 years there have been considerable advances in our understanding of the genetics of diabetes. Important discoveries have been made in dissecting the genes involved in rare monogenic forms of type 2 diabetes which has become a paradigm for genetic studies of type 2 diabetes. This review focuses on the main approaches currently adopted and our current understanding of the genes involved in susceptibility to type 2 diabetes.

CA-repeated microsatellite polymorphism of the glucokinase gene and its association with non-insulin-dependent diabetes mellitus in Taiwanese

Mutation of the glucokinase gene has recently been identified as a cause of maturity-onset diabetes of the young (MODY), a subset of non-insulin-dependent diabetes mellitus (NIDDM). However, its role in the wide variety of NIDDM remains controversial due to conflicting reports of association studies, negative results of linkage studies and low prevalence of glucokinase mutations in the common variety of NIDDM. In this study, two (CA)n-microsatellite polymorphisms flanking both ends of the glucokinase gene, termed GCK1 and GCK2, were used to evaluate the role of glucokinase on NIDDM susceptibility of Taiwanese. For GCK1, three alleles (Z,Z+2 and Z+4 with a polymorphic information content index (PIC) of 0.53) and six genotypes were evident in 119 Taiwanese. When compared with control subjects, the NIDDM group had a much less frequency of the Z+2 allele (14.0% vs. 23.9%). In addition, the Z+2 allele was noted to have a marginal protective effect for NIDDM in Taiwanese with the odds ratio of 0.52 (95% confidence interval (C.I.) 0.26-1.03, P = 0.058). For GCK2, four alleles (0, 2, 4 and 6 with a PIC of 0.48) and seven genotypes were identified. There was no significant difference in allele frequency between NIDDM and control groups in the locus of GCK2. Our data were in agreement with reports from American Blacks, Mauritian Creoles, Asian Indians, Japanese and Finnish--that there is a positive association of GCK1 and a negative association of GCK2 with NIDDM. Furthermore, the Z+2 allele was a protective factor for NIDDM in Taiwanese.