1.
Relationships between common polymorphisms of adenosine triphosphate-binding cassette transporter A1 and high-density lipoprotein cholesterol and coronary heart disease in a population with type 2 diabetes mellitus.
Porchay-Baldérelli, I, Péan, F, Emery, N, Maimaitiming, S, Bellili, N, Travert, F, Mohammedi, K, Roussel, R, Marre, M, Fumeron, F, et al
Metabolism: clinical and experimental. 2009;(1):74-9
Abstract
Patients with type 2 diabetes mellitus (T2D) have a high coronary risk partly because of low levels of high-density lipoprotein-cholesterol (HDL-C). The adenosine triphosphate-binding cassette transporter A1 (ABCA1) plays a key role in HDL metabolism. We studied the association of common single nucleotide polymorphisms (SNPs) in the ABCA1 gene with HDL-C levels and coronary risk in a cohort of subjects with T2D. We studied 5 SNPs: +69C>T, +378G>C, R219K, I883M, and R1587K. The C allele of +378G>C was significantly associated with lower HDL-C concentrations (P = .04); and the M allele of I883M, with higher HDL-C concentrations (P = .03). No significant association was found between these SNPs and the incidence of new coronary events. Nevertheless, cross-sectional data on entry showed that the frequency of K219 was lower in patients with previous coronary heart disease (angina pectoris and/or myocardial infarction) (odds ratio, OR [95% confidence interval, CI] = 0.80 [0.65-0.98], P = .03, after adjustment for multiple risk factors other than HDL-C). The frequency of K1587 was higher in patients with angina pectoris (OR [95% CI] = 1.27 [1.01-1.58], P = .04, after multiple adjustment). The TT genotype of the C69T SNP was less frequent in subjects with prior myocardial infarction (OR [95% CI] = 0.28 [0.13-0.61], P = .001, after multiple adjustment). These associations persisted after further adjustment for HDL-C levels. In conclusion, common genetic variations of ABCA1 had a moderate influence on HDL-C levels and/or coronary heart disease in patients with T2D. These 2 effects were independent.
2.
Genetic and epigenetic factors at COL2A1 and ABCA4 influence clinical outcome in congenital toxoplasmosis.
Jamieson, SE, de Roubaix, LA, Cortina-Borja, M, Tan, HK, Mui, EJ, Cordell, HJ, Kirisits, MJ, Miller, EN, Peacock, CS, Hargrave, AC, et al
PloS one. 2008;(6):e2285
Abstract
BACKGROUND Primary Toxoplasma gondii infection during pregnancy can be transmitted to the fetus. At birth, infected infants may have intracranial calcification, hydrocephalus, and retinochoroiditis, and new ocular lesions can occur at any age after birth. Not all children who acquire infection in utero develop these clinical signs of disease. Whilst severity of disease is influenced by trimester in which infection is acquired by the mother, other factors including genetic predisposition may contribute. METHODS AND FINDINGS In 457 mother-child pairs from Europe, and 149 child/parent trios from North America, we show that ocular and brain disease in congenital toxoplasmosis associate with polymorphisms in ABCA4 encoding ATP-binding cassette transporter, subfamily A, member 4. Polymorphisms at COL2A1 encoding type II collagen associate only with ocular disease. Both loci showed unusual inheritance patterns for the disease allele when comparing outcomes in heterozygous affected children with outcomes in affected children of heterozygous mothers. Modeling suggested either an effect of mother's genotype, or parent-of-origin effects. Experimental studies showed that both ABCA4 and COL2A1 show isoform-specific epigenetic modifications consistent with imprinting. CONCLUSIONS These associations between clinical outcomes of congenital toxoplasmosis and polymorphisms at ABCA4 and COL2A1 provide novel insight into the molecular pathways that can be affected by congenital infection with this parasite.
3.
Type 2 diabetes-associated missense polymorphisms KCNJ11 E23K and ABCC8 A1369S influence progression to diabetes and response to interventions in the Diabetes Prevention Program.
Florez, JC, Jablonski, KA, Kahn, SE, Franks, PW, Dabelea, D, Hamman, RF, Knowler, WC, Nathan, DM, Altshuler, D
Diabetes. 2007;(2):531-6
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Abstract
The common polymorphisms KCNJ11 E23K and ABCC8 A1369S have been consistently associated with type 2 diabetes. We examined whether these variants are also associated with progression from impaired glucose tolerance (IGT) to diabetes and responses to preventive interventions in the Diabetes Prevention Program. We genotyped both variants in 3,534 participants and performed Cox regression analysis using genotype, intervention, and their interactions as predictors of diabetes incidence over approximately 3 years. We also assessed the effect of genotype on insulin secretion and insulin sensitivity at 1 year. As previously shown in other studies, lysine carriers at KCNJ11 E23K had reduced insulin secretion at baseline; however, they were less likely to develop diabetes than E/E homozygotes. Lysine carriers were less protected by 1-year metformin treatment than E/E homozygotes (P < 0.02). Results for ABCC8 A1369S were essentially identical to those for KCNJ11 E23K. We conclude that the lysine variant in KCNJ11 E23K leads to diminished insulin secretion in individuals with IGT. Given our contrasting results compared with case-control analyses, we hypothesize that its effect on diabetes risk may occur before the IGT-to-diabetes transition. We further hypothesize that the diabetes-preventive effect of metformin may interact with the impact of these variants on insulin regulation.