Beta2-adrenoceptor polymorphisms and asthma from childhood to middle age in the British 1958 birth cohort: a genetic association study.

BACKGROUND: Functionally relevant polymorphisms of the beta2-adrenoceptor gene (ADRB2) are common in white populations, but their contribution to the burden of airways disease in the population is uncertain. We aimed to relate the long-term prevalence of asthma or wheeze to functional coding region polymorphisms in the ADRB2 gene. METHODS: The British 1958 birth cohort consisted of all people born in Britain during a week in 1958. Asthma, wheezy bronchitis, and wheezing were ascertained by interview at ages 7, 11, 16, 23, 33, and 42 years, and lung function tests at 35 and 45 years. DNA samples from 8018 participants in the 45-year follow-up were genotyped for three coding variants in the ADRB2 gene. We extend the follow-up of this nationwide cohort by a further 10 years and relate asthma prevalence, prognosis, and lung function to functional coding region polymorphisms in the ADRB2 gene in the cohort members who contributed DNA samples. We also compared and combined our findings with those reaching significance in two previous meta-analyses. FINDINGS: Half the cohort (4105 of 8018) had some history of wheezing illness by age 42 years. Neither lifetime prevalence nor age at onset were related to ADRB2 coding variants. However, the common polymorphisms Arg16Gly (rs1042713, Arg 16 allele frequency 36.3%) and Gln27Glu (rs1042714, Glu 27 allele frequency 44.6%) were significantly associated with persistence of asthmatic symptoms from childhood to middle age. Among homozygotes for the Arg16-Gln27 haplotype at these loci, 19.3% (41 of 212) childhood wheezers had five or more wheezing episodes in the past year at age 42, compared with 11.9% (71 of 599) with no copy of this haplotype. However, only 3% of all frequent adult wheezing was statistically attributable to this haplotype. The less common Thr164Ile polymorphism (rs1800888, Ile allele frequency 1.5%) was not a major predictor of either frequency or prognosis of asthma. Our data do not support the findings of previous meta-analyses when considered in isolation or when combined with their contributory studies. INTERPRETATION: ADRB2 polymorphisms might predict a small component of the long-term prognosis in childhood asthma, but are not important determinants of asthma incidence or prevalence in the British population.

Sequence variants affecting eosinophil numbers associate with asthma and myocardial infarction.

Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of inflammatory responses and thus have important roles in the pathogenesis of inflammatory diseases. Here we describe a genome-wide association scan for sequence variants affecting eosinophil counts in blood of 9,392 Icelanders. The most significant SNPs were studied further in 12,118 Europeans and 5,212 East Asians. SNPs at 2q12 (rs1420101), 2q13 (rs12619285), 3q21 (rs4857855), 5q31 (rs4143832) and 12q24 (rs3184504) reached genome-wide significance (P = 5.3 x 10(-14), 5.4 x 10(-10), 8.6 x 10(-17), 1.2 x 10(-10) and 6.5 x 10(-19), respectively). A SNP at IL1RL1 associated with asthma (P = 5.5 x 10(-12)) in a collection of ten different populations (7,996 cases and 44,890 controls). SNPs at WDR36, IL33 and MYB that showed suggestive association with eosinophil counts were also associated with atopic asthma (P = 4.2 x 10(-6), 2.2 x 10(-5) and 2.4 x 10(-4), respectively). We also found that a nonsynonymous SNP at 12q24, in SH2B3, associated significantly (P = 8.6 x 10(-8)) with myocardial infarction in six different populations (6,650 cases and 40,621 controls).

Genetic variation at the growth hormone (GH1) and growth hormone receptor (GHR) loci as a risk factor for hypertension and stroke.

An increased prevalence of both hypertension and cerebrovascular stroke is apparent in growth hormone (GH) deficiency whilst hypertension is a frequent complication in acromegaly. This has suggested a possible link between GH, stature and arterial function. Since the risk of both hypertension and stroke also appears to be inversely correlated with adult height, we have instigated an exploratory study to assess whether inter-individual variation in the genes encoding human growth hormone (GH1) and the GH receptor (GHR) might be associated with an increased risk of hypertension and stroke. GH1 promoter haplotypes were found to differ significantly not only between hypertensive patients (n = 111) and controls (n = 121) but also between stroke patients (n = 155) and controls (n = 158). Intriguingly, the association between GH1 promoter haplotype and risk of hypertension was much greater in females than in males. An inverse correlation between height and central systolic blood pressure was apparent in both hypertensive patients and normal controls but was much stronger in individuals carrying at least one GH1 promoter risk haplotype. The GH1 genotype therefore constitutes a risk factor for hypertension that interacts with stature. A strong association was found between the presence of at least one GH1 risk haplotype and a family history of stroke at an early age (odds ratio: 9.07, 95% confidence interval: 1.14-72.22). Three novel GH variants (Arg16His, Phe176Cys, Cys189Arg) were identified during the course of this study. Although two exhibited markedly reduced biological activity in vitro, their clinical significance remains unclear. No association was found between GHR genotype and either hypertension or stroke, nor was any interaction noted between GHR and GH1 genotypes in terms of a disease association. However, an association between GHRd3 genotype and hypertension was observed among stroke patients, particularly females. Elevated HDL was found to be a risk factor for hypertension in individuals lacking a copy of the GHRd3 allele. Weak associations with GHR genotype were also noted for peripheral systolic and diastolic blood pressure in hypertensive patients. Although the underlying mechanisms are still unclear, our findings are consistent with a complex relationship between height, hypertension, GH1 promoter haplotype, GHR polymorphism and the risk of stroke.

5-Lipoxygenase polymorphism and in-vivo response to leukotriene receptor antagonists.

OBJECTIVE: To determine whether genetic polymorphisms of the core promoter region of the 5-lipoxygenase gene contribute to the clinical response to leukotriene receptor antagonists. METHODS: We retrospectively genotyped 52 asthmatics for mutations of this gene from four placebo-controlled studies measuring leukotriene receptor antagonist responses. All studies measured bronchodilator response, and bronchial hyperresponsiveness to adenosine monophosphate was measured in three studies ( n = 34). RESULTS: Of the 52 patients genotyped, 40 were homozygous wild type, 12 heterozygous, and none was homozygous mutant. There was no significant difference in any improvements conferred by leukotriene receptor antagonists versus placebo in the forced expiratory volume in 1 s (0.20 l for wild-type homozygotes and 0.01 l for heterozygotes), forced mid-expiratory flow rate (0.16 l/s and 0.14 l/s), peak expiratory flow rate (10 l/min and 29 l/min) and adenosine monophosphate 20% fall in forced expiratory volume in 1 s (2.8-fold shift and 2.3-fold shift) between the two genotypes. CONCLUSION: In our population, screening for this polymorphism as an aid to guiding treatment is probably not worthwhile. In addition, we found no difference between homozygous wild types and heterozygotes in terms of bronchodilator response or bronchial hyperresponsiveness with leukotriene receptor antagonists.

Identification of the autoantigen SART-1 as a candidate gene for the development of atopy.

The possibility that immune responses to autoantigens may contribute to the development of atopic disease has been largely ignored. In this paper, we describe the chromosomal localization of the gene for squamous cell carcinoma-associated reactive antigen for cytotoxic T cells (SART-1). The SART-1 gene localized to a region of 11q12-13 showing strong linkage to atopy in previous studies. Further analysis of this gene revealed the presence of at least 20 exons of varying lengths and four novel single-nucleotide polymorphisms, one of which resulted in an amino acid substitution. Association analysis in families recruited on the basis of affected sib pairs for asthma reveal significant association for both coding region polymorphisms with atopy. We therefore hypothesize that polymorphic variation within the SART-1 gene may account for individuals developing atopy.