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A common variant of the AMPD1 gene predicts improved cardiovascular survival in patients with coronary artery disease.

OBJECTIVE: We tested whether a common AMPD1 gene variant is associated with improved cardiovascular (CV) survival in patients with coronary artery disease (CAD). BACKGROUND: Reduced activity of adenosine monophosphate deaminase (AMPD) may increase production of adenosine, a cardioprotective agent. A common, nonsense, point variant of the AMPD1 gene (C34T) results in enzymatic inactivity and has been associated with prolonged survival in heart failure. METHODS: Blood was collected from 367 patients undergoing coronary angiography. Genotyping was done by polymerase chain reaction amplification and restriction enzyme digestion, resulting in allele-specific fragments. Coronary artery disease was defined as > or =70% stenosis of > or =1 coronary artery. Patients were followed prospectively for up to 4.8 years. Survival statistics compared hetero- (+/-) or homozygotic (-/-) carriers with noncarriers. RESULTS: Patients were 66 +/- 10 years old; 79% were men; 22.6% were heterozygous and 1.9% homozygous for the variant AMPD1(-) allele. During a mean of 3.5 +/- 1.0 years, 52 patients (14.2%) died, 37 (10.1%) of CV causes. Cardiovascular mortality was 4.4% (4/90) in AMPD1(-) allele carriers compared with 11.9% (33/277) in noncarriers (p = 0.046). In multiple variable regression analysis, only age (hazard ratio, 1.11/year, p < 0.001) and AMPD1(-) carriage (hazard ratio, 0.36, p = 0.053) were independent predictors of CV mortality. CONCLUSIONS: Carriage of a common variant of the AMPD1 gene was associated with improved CV survival in patients with angiographically documented CAD. The dysfunctional AMPD1(-) allele may lead to increased cardiac adenosine and increased cardioprotection during ischemic events. Adenosine monophosphate deaminase-1 genotyping should be further explored in CAD for prognostic, mechanistic and therapeutic insights.

AMP Deaminase↗

Common variants in maturity-onset diabetes of the young genes contribute to risk of type 2 diabetes in Finns.

Prior reports have suggested that variants in the genes for maturity-onset diabetes of the young (MODY) may confer susceptibility to type 2 diabetes, but results have been conflicting and coverage of the MODY genes has been incomplete. To complement our previous studies of HNF4A, we examined the other five known MODY genes for association with type 2 diabetes in Finnish individuals. For each of the five genes, we selected 1) nonredundant single nucleotide polymorphisms (SNPs) (r(2)< 0.8 with other SNPs) from the HapMap database or another linkage disequilibrium map, 2) SNPs with previously reported type 2 diabetes association, and 3) nonsynonymous coding SNPs. We tested 128 SNPs for association with type 2 diabetes in 786 index cases from type 2 diabetic families and 619 normal glucose-tolerant control subjects. We followed up 35 of the most significant SNPs by genotyping them on another 384 case subjects and 366 control subjects from Finland. We also supplemented our previous HNF4A results by genotyping 12 SNPs on additional Finnish samples. After correcting for testing multiple correlated SNPs within a gene, we find evidence of type 2 diabetes association with SNPs in five of the six known MODY genes: GCK, HNF1A, HNF1B, NEUROD1, and HNF4A. Our data suggest that common variants in several MODY genes play a modest role in type 2 diabetes susceptibility.

Basic Helix-Loop-Helix Proteins↗

Common variants at the PCOL2 and Sp1 binding sites of the COL1A1 gene and their interactive effect influence bone mineral density in Caucasians.

BACKGROUND: Osteoporosis, mainly characterised by low bone mineral density (BMD), is a serious public health problem. The collagen type I alpha 1 (COL1A1) gene is a prominent candidate gene for osteoporosis. Here, we examined whether genetic variants at the COL1A1 gene can influence BMD variation. METHODS: BMD was measured at nine skeletal sites in 313 Caucasian males and 308 Caucasian females. We screened four single nucleotide polymorphisms (SNPs) at the COL1A1 gene: PCOL2 (-1997 G/T) in the promoter, Sp1 (1546 G/T) in the intron 1, Gly19Cys (3911 G/A) in exon 8, and Ala897Thr (13 773 G/A) in exon 45. Univariate and multivariate association approaches were used in the analyses. RESULTS: In multivariate analyses, we found a strong association between the PCOL2 SNP and BMD (p = 0.007 to 0.024) and a suggestive association between the Sp1 SNP and BMD (p = 0.023 to 0.048) in elderly Caucasian females. Interestingly, the interaction of these two SNPs was highly significantly associated with BMD variation (p = 0.001 to 0.003). The haplotype GG at the two SNPs had, on average, 2.7% higher BMD than non-carriers (p = 0.006 to 0.026). CONCLUSIONS: Our data suggested that the common genetic variants at the PCOL2 and Sp1 sites, and importantly, their interactive effects, may contribute to BMD variation in elderly Caucasian females. Further studies are necessary to delineate the mechanisms underlying the effects of these common variants on BMD variation and to test their clinical relevance for general populations. In addition, our study highlighted the importance of multivariate analyses when multiple correlated phenotypes are under study.

Binding Sites↗

Common variants in RB1 gene and risk of invasive ovarian cancer.

Somatic alteration of the RB1 gene is common in several types of cancer, and germ-line variants are implicated in others. We have used a single nucleotide polymorphism (SNP) tagging approach to evaluate the association between common variants (SNP) in RB1 and risks of invasive ovarian cancer. We genotyped 11 tagging SNPs in three ovarian case-control studies from the United Kingdom, United States, and Denmark, comprising >1500 cases and 4,800 controls. Two SNPs showed significant association with ovarian cancer risk: carriers of the minor allele of rs2854344 were at reduced risk compared with the common homozygotes [odds ratio (OR), 0.73; 95% confidence interval (95% CI), 0.61-0.89; P = 0.0009 dominant model]. Similarly, the minor allele of rs4151620 was found to be associated with reduced risk (rare versus common homozygote; OR, 0.19; 95% CI, 0.07-0.53; P = 0.00005 recessive model). After adjusting for multiple testing, the most significant association (rs4151620) was P = 0.001. A global test comparing common haplotype frequencies in cases and controls was of borderline significance (P(8df) = 0.04). There are no common coding SNPs in the RB1 gene. However, intron 17 of RB1 contains the open reading frame for the P2RY5 gene, and rs4151620 is perfectly correlated with rs2227311, which is located in the 5'-untranslated region of P2RY5 and is predicted to affect P2RY5 transcription. rs2854344 has been reported previously to be associated with breast cancer risk. The possible associations of rs2854344 and rs4151620 with ovarian cancer risk warrant confirmation in independent case-control studies before studies on their biological mode of action.

Case-Control Studies↗

A common variant associated with prostate cancer in European and African populations.

With the increasing incidence of prostate cancer, identifying common genetic variants that confer risk of the disease is important. Here we report such a variant on chromosome 8q24, a region initially identified through a study of Icelandic families. Allele -8 of the microsatellite DG8S737 was associated with prostate cancer in three case-control series of European ancestry from Iceland, Sweden and the US. The estimated odds ratio (OR) of the allele is 1.62 (P = 2.7 x 10(-11)). About 19% of affected men and 13% of the general population carry at least one copy, yielding a population attributable risk (PAR) of approximately 8%. The association was also replicated in an African American case-control group with a similar OR, in which 41% of affected individuals and 30% of the population are carriers. This leads to a greater estimated PAR (16%) that may contribute to higher incidence of prostate cancer in African American men than in men of European ancestry.

Alleles↗

Common variants in myocardial ion channel genes modify the QT interval in the general population: results from the KORA study.

Altered myocardial repolarization is one of the important substrates of ventricular tachycardia and fibrillation. The influence of rare gene variants on repolarization is evident in familial long QT syndrome. To investigate the influence of common gene variants on the QT interval we performed a linkage disequilibrium based SNP association study of four candidate genes. Using a two-step design we analyzed 174 SNPs from the KCNQ1, KCNH2, KCNE1, and KCNE2 genes in 689 individuals from the population-based KORA study and 14 SNPs with results suggestive of association in a confirmatory sample of 3277 individuals from the same survey. We detected association to a gene variant in intron 1 of the KCNQ1 gene (rs757092, +1.7 ms/allele, P=0.0002) and observed weaker association to a variant upstream of the KCNE1 gene (rs727957, +1.2 ms/allele, P=0.0051). In addition we detected association to two SNPs in the KCNH2 gene, the previously described K897T variant (rs1805123, -1.9 ms/allele, P=0.0006) and a gene variant that tags a different haplotype in the same block (rs3815459, +1.7 ms/allele, P=0.0004). The analysis of additive effects by an allelic score explained a 10.5 ms difference in corrected QT interval length between extreme score groups and 0.951 of trait variance (P<0.00005). These results confirm previous heritability studies indicating that repolarization is a complex trait with a significant heritable component and demonstrate that high-resolution SNP-mapping in large population samples can detect and fine map quantitative trait loci even if locus specific heritabilities are small.

Adult↗

Blunted renal vascular response to angiotensin II is associated with a common variant of the angiotensinogen gene and obesity.

OBJECTIVE: Recently, we reported evidence for genetic linkage between human essential hypertension and the angiotensinogen gene (AGT) and an association with a common molecular variant of this gene (methionine 235 --> threonine or T235). Other studies had led us to hypothesize that blunted renal plasma flow responses to infused angiotensin II (Ang II) when in high salt balance may reflect increased intrarenal formation of Ang II, a condition that might promote hypertension. Here we examine the relationship between AGT genotype and renal vascular response to infused Ang II. METHODS: Hypertensive (n = 34, all off medication) and normotensive (n = 57) members of families with a history of hypertension (age 18-60 years) as well as 29 normotensive volunteers without a family history of hypertension were studied after controlled diets with 200 mequiv./day sodium. Ang II was infused at a mildly pressor dose (3 ng/kg/min) and renal plasma flow was determined by steady-state plasma para-aminohippurate concentration. RESULTS: After correction for covariates in multivariate analyses, participants homozygous for the T235 variant had significantly diminished renal plasma flow responses to the Ang II infusion (P = 0.005). Changes in renal arterial resistance were also blunted in the T235 homozygotes. Similar results were found when analysis was restricted to normotensive participants or subdivided based on family history of hypertension. No confounding factors associated with AGT genotype that could explain these differences were found. Furthermore, obesity, which also suppressed renovascular response to Ang II, was found to interact significantly (P = 0.017) with genotype such that, among T235 homozygotes, obesity had a greater blunting effect on renal vascular response. CONCLUSIONS: Expected renovascular response to infused Ang II was blunted in persons with the AGT TT genotype. This is the first report of an association between a specific gene variant and altered renal physiology in humans with particular relevance to essential hypertension.

Adolescent↗

A common variant of the methylenetetrahydrofolate reductase gene (1p36) is associated with an increased risk of cancer.

Folate metabolism is thought to play an important role in carcinogenesis through its involvement in both DNA methylation and nucleotide synthesis. A common Ala(222)/Val variant in the methylenetetrahydrofolate reductase (MTHFR) gene leads to a disturbed folate metabolism and is associated with decreased genomic DNA methylation. We previously reported that the MTHFR Val/Val genotype was associated with increased cancer mortality in men from a population-based cohort of subjects ages > or = 85 years. To further explore the deleterious effects of the MTHFR genotype, we studied the association of the genotype with cancer risk in 860 men ages 65-84 years who were followed >10 years (Zutphen Elderly Study). During follow-up, 149 new cases of cancer occurred among the 793 men without cancer at baseline. The risk of developing cancer was 1.80-fold (95% confidence interval, 1.09-3.00) higher among men with the Val/Val genotype than among men with the Ala/Ala genotype. Except for lung cancer [relative risk (RR), 1.15], the risks of common forms of cancers were significantly increased among men with the Val/Val genotype [cancer of the prostate (RR, 3.48); the colorectum (RR, 3.65); the kidney and bladder (RR, 5.48)]. The risks of cancer were particularly increased among men with a lower folate and a higher alcohol intake and men of an older age. In conclusion, our current and previous studies in two independent populations indicate that a common Ala/Val variant in the MTHFR gene is a risk factor for cancer in elderly men from the general population. The mechanism underlying this association might involve genomic instability as a result of insufficient methylation of genomic DNA.

Aged↗

Intrahepatic cholestasis of pregnancy: the severe form is associated with common variants of the hepatobiliary phospholipid transporter ABCB4 gene.

BACKGROUND: Intrahepatic cholestasis of pregnancy (ICP) is characterised by troublesome maternal pruritus, raised serum bile acid levels and increased fetal risk. Mutations of the ABCB4 gene encoding the hepatobiliary phospholipid transporter have been identified in a small proportion of patients with cholestasis of pregnancy. In a recent prospective study on 693 patients with cholestasis of pregnancy, a cut-off level for serum bile acid (> or =40 micromol/l) was determined for increased risk of fetal complications. OBJECTIVES: To investigate whether common combinations of polymorphic alleles (haplotypes) of the genes encoding the hepatobiliary ATP-binding cassette (ABC) transporters for phospholipids (ABCB4) and bile acids (ABCB11) were associated with this severe form of cholestasis of pregnancy. METHODS: For genetic analysis, 52 women with bile acid levels > or =40 micromol/l (called cases) and 52 unaffected women (called controls) matched for age, parity and geographical residence were studied. Gene variants tagging common ABCB4 and ABCB11 haplotypes were genotyped and haplotype distributions were compared between cases and controls by permutation testing. RESULTS: In contrast with ABCB11 haplotypes, ABCB4 haplotypes differed between the two groups (p = 0.019), showing that the severe form of cholestasis of pregnancy is associated with the ABCB4 gene variants. Specifically, haplotype ABCB4_5 occurred more often in cases, whereas haplotypes ABCB4_3 and ABCB4_7 were more common in controls. These associations were reflected by different frequencies of at-risk alleles of the two tagging polymorphisms (c.711A: odds ratio (OR) 2.27, p = 0.04; deletion intron 5: OR 14.68, p = 0.012). CONCLUSION: Variants of ABCB4 represent genetic risk factors for the severe form of ICP in Sweden.

ATP Binding Cassette Transporter, Subfamily B↗

Left-sided leg edema of the elderly: a common variant of the iliac compression syndrome.

BACKGROUND: Anatomically, the right common iliac artery crosses the left iliac vein and its accompanying lymphatics. We hypothesized that this situation could lead to a predominance of edema, telangiectasis, and venous varicosities on the left lower extremities of older persons. METHODS: To test this hypothesis, a research assistant who was blinded to the study goals examined 215 predominantly elderly residents of North Carolina homes for the aged and disabled. RESULTS: Among these subjects, 17.7 percent had predominantly left-sided edema, and 5.7 percent had predominantly right-sided edema (P < 0.001). When the 88 subjects with pitting edema greater than 3 mm were studied, 34.5 percent showed a left-sided predominance, and 6.9 percent showed a right-sided predominance (P < 0.001). In contrast, no significant difference was found in the lateralization of venous varicosities or of telangiectasis. CONCLUSIONS: Asymmetric edema is common and is usually left-sided in older persons. Compression of the left common iliac vein and its accompanying lymphatics by the right iliac artery, rather than overt clinical disease, might explain the majority of asymmetric edema seen in clinical practice.

Adult↗

Associations of classic Kaposi sarcoma with common variants in genes that modulate host immunity.

Classic Kaposi sarcoma (CKS) is an inflammatory-mediated neoplasm primarily caused by Kaposi sarcoma-associated herpesvirus (KSHV). Kaposi sarcoma lesions are characterized, in part, by the presence of proinflammatory cytokines and growth factors thought to regulate KSHV replication and CKS pathogenesis. Using genomic DNA extracted from 133 CKS cases and 172 KSHV-latent nuclear antigen-positive, population-based controls in Italy without HIV infection, we examined the risk of CKS associated with 28 common genetic variants in 14 immune-modulating genes. Haplotypes were estimated for IL1A, IL1B, IL4, IL8, IL8RB, IL10, IL12A, IL13, and TNF. Compared with controls, CKS risk was decreased with 1235T/-1010G-containing diplotypes of IL8RB (odds ratio, 0.49; 95% confidence interval, 0.30-0.78; P = 0.003), whereas risk was increased with diplotypes of IL13 containing the promoter region variant 98A (rs20541, alias +130; odds ratio, 1.88; 95% confidence interval, 1.15-3.08; P = 0.01) when considered in multivariate analysis. Risk estimates did not substantially vary by age, sex, incident disease, or disease burden. Our data provide preliminary evidence for variants in immune-modulating genes that could influence the risk of CKS. Among KSHV-seropositive Italians, CKS risk was associated with diplotypes of IL8RB and IL13, supporting laboratory evidence of immune-mediated pathogenesis.

Adult↗

Analysis of CARD15 polymorphisms in Korean patients with ankylosing spondylitis reveals absence of common variants seen in western populations.

OBJECTIVE: Substantial epidemiological and genetic evidence suggests that ankylosing spondylitis (AS) is likely due to an interplay of genetic and environmental factors. Recently, CARD15, located in chromosome 16q12, has been established as a disease susceptibility gene for Crohn's disease, Blau syndrome, and possibly psoriatic arthritis. Association studies in admixed populations from Northern European ancestry noted no such association between CARD15 mutations and AS. However, a homogenous population has yet to be studied. We investigated the prevalence of the 3 common CARD15 variants in a homogenous Korean population with AS. METHODS: All subjects were native Koreans with AS satisfying the modified New York criteria. Korean controls were examined and confirmed to be unaffected by AS. Subjects with AS were genotyped for the R702W, G908R, and Leu1007fsinsC variants of CARD15 using mass array MALDI-TOF mass spectrometry. RESULTS: A total of 205 AS subjects and 200 controls were genotyped. No subject with AS had any variants at the 702 and 1007 sites of CARD15. Only one subject was heterozygous for the 908 variant. The overall genotype frequency in AS for any CARD15 variant was 0.5%. No control had any of the 3 CARD15 variants. CONCLUSION: Our findings indicate that the CARD15 gene is not a major contributor to AS susceptibility in the Korean population.

Adult↗

A common variant located in the 3'UTR of the RET gene is associated with protection from Hirschsprung disease.

Complex diseases are common genetic disorders showing familial aggregation but no typical Mendelian inheritance. Hirschsprung disease (HSCR), a developmental disorder characterized by the absence of enteric neurons in distal segments of the gut, shows a complex pattern of inheritance, with the RET protooncogene acting as a major gene and additional susceptibility loci playing minor roles. In the last years, we have identified a "protective" RET haplotype, which is underrepresented in HSCR patients with respect to controls. Here, we demonstrate that the protective effect of this haplotype is due to a variant located in the 3' untranslated region (UTR) of the RET gene, which slows down the physiological mRNA decay of the gene transcripts. Such a functional effect of this common RET variant explains the under-representation of the whole haplotype and its role as a modifying factor in HSCR pathogenesis.

3' Untranslated Regions↗

The role of a common variant of the cholesteryl ester transfer protein gene in the progression of coronary atherosclerosis. The Regression Growth Evaluation Statin Study Group.

BACKGROUND: The high-density lipoprotein (HDL) cholesterol concentration is inversely related to the risk of coronary artery disease. The cholesteryl ester transfer protein (CETP) has a central role in the metabolism of this lipoprotein and may therefore alter the susceptibility to atherosclerosis. METHODS: The DNA of 807 men with angiographically documented coronary atherosclerosis was analyzed for the presence of a polymorphism in the gene coding for CETP. The presence of this DNA variation was referred to as B1, and its absence as B2. All patients participated in a cholesterol-lowering trial designed to induce the regression of coronary atherosclerosis and were randomly assigned to treatment with either pravastatin or placebo for two years. RESULTS: The B1 variant of the CETP gene was associated with both higher plasma CETP concentrations (mean [+/-SD], 2.29+/-0.62 microg per milliliter for the B1B1 genotype vs. 1.76+/-0.51 microg per milliliter for the B2B2 genotype) and lower HDL cholesterol concentrations (34+/-8 vs. 39+/-10 mg per deciliter). In addition, we observed a significant dose-dependent association between this marker and the progression of coronary atherosclerosis in the placebo group (decrease in mean luminal diameter: 0.14+/-0.21 mm for the B1B1 genotype, 0.10+/-0.20 mm for the B1B2 genotype, and 0.05+/-0.22 mm for the B2B2 genotype). This association was abolished by pravastatin. Pravastatin therapy slowed the progression of coronary atherosclerosis in B1B1 carriers but not in B2B2 carriers (representing 16 percent of the patients taking pravastatin). CONCLUSIONS: There is a significant relation between variation at the CETP gene locus and the progression of coronary atherosclerosis that is independent of plasma HDL cholesterol levels and the activities of lipolytic plasma enzymes. This common DNA variant appears to predict whether men with coronary artery disease will benefit from treatment with pravastatin to delay the progression of coronary atherosclerosis.

Anticholesteremic Agents↗

A truncated hMSH2 transcript occurs as a common variant in the population: implications for genetic diagnosis.

Germline mutations of the hMSH2 gene are responsible for many cases of hereditary nonpolyposis colorectal cancer. While screening for hMSH2 gene mutations in hereditary nonpolyposis colorectal cancer kindreds, we observed that a previously reported germline mutation is in fact a common, alternatively spliced variant in the population. Using RT-PCR and the protein truncation test, the hMSH2 exon 13 deletion variant was found in more than 90% of individuals. The exon 13 deletion transcript was only present in lymphocyte RNA, no abnormalities were detected in genomic DNA flanking exon 13, and the deletion transcript is apparently not translated. These findings highlight further that caution should be exercised in providing genetic risk assessment on the basis of currently used germline mutation detection strategies.

Colorectal Neoplasms↗

Insulin resistance: interactions between obesity and a common variant of insulin receptor substrate-1.

We previously discovered two aminoacid polymorphisms in codons 513 and 972 of the protein insulin receptor substrate-1 (IRS-1), which is important in cellular insulin action. We have investigated whether these polymorphisms are associated with changes in insulin sensitivity in a random sample of young healthy adults. Insulin sensitivity and secretion were measured during a combined intravenous glucose and tolbutamide tolerance test in 380 unrelated white subjects aged 18-32. IRS-1 polymorphisms were examined by single-strand conformation polymorphism and verified by restriction-enzyme digestion. No homozygous carrier of the codon-513 variant was identified, but one non-obese man had the codon-972 mutation on both alleles. He had low fasting-serum insulin and C-peptide concentrations and low insulin sensitivity and glucose effectiveness. During a 24 h dexamethasone test, he developed transient diabetes. In their heterozygous forms the codon-513 and codon-972 variants of IRS-1 were found in 3% and 9% of the subjects. Non-obese carriers of either polymorphism had similar insulin sensitivity and pancreatic beta-cell function to non-obese wild-type subjects (no known variants of IRS-1). Analysis of variance showed, however, a significant interaction between obesity (body-mass index > or = 25 kg/m2) and the heterozygous form of the codon-972 variant (p < 0.003); obese polymorphism carriers had lower insulin sensitivity than obese non-carriers (mean 6.0 [SD 3.3] vs 12.3 [9.5] x 10(-5) L min-1 pmol-1). The obese carriers of the codon-972 variant were also characterised by a clustering of metabolic cardiovascular risk factors, with raised fasting concentrations of plasma glucose, serum triglyceride, and plasma tissue-plasminogen-activator and its fast-acting inhibitor. With adjustment for known modulators of insulin sensitivity, multivariate analyses showed that the combination of obesity and the codon-972 variant was associated with a 50% reduction in insulin sensitivity (p = 0.0008). Our results suggest that the codon-972 IRS-1 gene variant may interact with obesity in the pathogenesis of common insulin-resistant disorders.

Adolescent↗

Common variants in the ENPP1 gene are not reproducibly associated with diabetes or obesity.

The common missense single nucleotide polymorphism (SNP) K121Q in the ectoenzyme nucleotide pyrophosphate phosphodiesterase (ENPP1) gene has recently been associated with type 2 diabetes in Italian, U.S., and South-Asian populations. A three-SNP haplotype, including K121Q, has also been associated with obesity and type 2 diabetes in French and Austrian populations. We set out to confirm these findings in several large samples. We genotyped the haplotype K121Q (rs1044498), rs1799774, and rs7754561 in 8,676 individuals of European ancestry with and without type 2 diabetes, in 1,900 obese and 930 lean individuals of European ancestry from the U.S. and Poland, and in 1,101 African-American individuals. Neither the K121Q missense polymorphism nor the putative risk haplotype were significantly associated with type 2 diabetes or BMI. Two SNPs showed suggestive evidence of association in a meta-analysis of our European ancestry samples. These SNPs were rs7754561 with type 2 diabetes (odds ratio for the G-allele, 0.85 [95% CI 0.78-0.92], P = 0.00003) and rs1799774 with BMI (homozygotes of the delT-allele, 0.6 [0.42-0.88], P = 0.007). However, these findings are not supported by other studies. We did not observe a reproducible association between these three ENPP1 variants and BMI or type 2 diabetes.

Asian People↗

[Genetics of atrial fibrillation: rare mutations, common variants and clinical relevance?].

Atrial fibrillation (AF) is considered the, by far, the most common arrhythmia of man, affecting millions of patients worldwide. The high socio-economic relevance is due to several severe complications and therefore requires profound scientific research in the field of etiology and treatment options. Atrial fibrillation typically occurs in the older patient who often suffers from a number of underlying diseases that act as predisposing factors. That genetics contribute strongly to this rhythm disorder is therefore not evident at a first glance. However, there are a number of investigations that prove familial accumulation for lone AF. Furthermore it is remarkable that many older patients suddenly develop atrial fibrillation without underlying disease, while others remain in sinus rhythm although suffering from a series of risk factors. Considering all this, genetic interference becomes most probable. Therefore in the recent past remarkable endeavours have been ventured to clarify the genetic basis of both lone AF and AF in the context of underlying diseases. For the former, until now four different genetic loci and three disease genes have been identified as causative. Concerning AF in the general population, mainly studies turning the spotlight on single-nucleotide polymorphisms (SNPs) have been applied. It is assumed that SNPs in disease-causing genes are distributed differentially among healthy and diseased individuals. These differences in frequency have been investigated with case-control studies. Up to now six different genes have been found to be associated with AF, including the genes for angiotensin-converting enzyme, angiotensinogen and several cardiac ion channels. Promising new technologies, especially high-throughput SNP genotyping and the genome wide scan for new candidate genes using chip arrays capable of genotyping up to 500 000 SNPs at a time, will multiply the speed to achieve new results. With that the possibility, approaches to optimize existing therapies and to open up new pathways to treat AF.

Atrial Fibrillation↗