Novel Polymorphisms Influencing Transcription of the Human CHRM2 Gene in Airway Smooth Muscle

Factors Associated with Decisions for Initial Dosing, Up-Titration of Propiverine and Treatment Outcomes in Overactive Bladder Syndrome Patients in a Non-Interventional Setting

Two doses of propiverine ER (30 and 45 mg/d) are available for the treatment of overactive bladder (OAB) syndrome. We have explored factors associated with the initial dosing choice (allocation bias), the decision to adapt dosing (escalation bias) and how dosing relative to other factors affects treatment outcomes. Data from two non-interventional studies of 1335 and 745 OAB patients, respectively, receiving treatment with propiverine, were analyzed post-hoc. Multivariate analysis was applied to identify factors associated with dosing decisions and treatment outcomes. Several parameters were associated with dose choice, escalation to higher dose or treatment outcomes, but only few exhibited a consistent association across both studies. These were younger age for initial dose choice and basal number of urgency and change in incontinence episodes for up-titration. Treatment outcome (difference between values at 12 weeks vs. baseline) for each OAB system was strongly driven by the respective baseline value, whereas no other parameter exhibited a consistent association. Patients starting on the 30 mg dose and escalating to 45 mg after 4 weeks had outcomes comparable with those staying on a starting dose of 30 or 45 mg. We conclude that dose escalation after 4 weeks brings OAB patients with an initially limited improvement to a level seen in initially good responders. Analysis of underlying factors yielded surprisingly little consistent insight.

African-specific variability in the acetylcholine muscarinic receptor M4: association with cocaine and heroin addiction

AIM

This study was designed to determine whether polymorphisms in acetylcholine receptors contribute to opioid dependence and/or cocaine dependence.

PATIENTS & METHODS

The sample (n = 1860) was divided by drug and ancestry, and 55 polymorphisms (nine genes) were analyzed.

RESULTS

Of the 20 SNPs that showed nominally significant associations, the association of the African-specific CHRM4 SNP rs2229163 (Asn417=) with cocaine dependence survived correction for multiple testing (Pcorrected = 0.047). CHRM4 is located in a region of strong linkage disequilibrium on chromosome 11 that includes genes associated with schizophrenia. CHRM4 SNP rs2229163 is in strong linkage disequilibrium with several African-specific SNPs in DGKZ and AMBRA1.

CONCLUSION

Cholinergic receptors' variants may contribute to drug addiction and have a potential role as pharmacogenetic markers.

The role of TGF-β in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by chronic oligoanovulation and hyperandrogenism and associated with insulin resistance, type 2 diabetes, and cardiovascular risk. In recent years, genetic studies have linked PCOS to a dinucleotide marker D19S884 in the fibrillin 3 gene. Fibrillins make up the major component of microfibrils in the extracellular matrix (ECM) and interact with molecules in the ECM to regulate transforming growth factor β (TGF-β) signaling. Therefore, variations in fibrillin 3 and subsequent dysregulation of TGF-β may contribute to the pathogenesis of PCOS. Here, we review the evidence from genetic studies supporting the role of TGF-β in PCOS and describe how TGF-β dysregulation may contribute to (1) the fetal origins of PCOS, (2) reproductive abnormalities in PCOS, and (3) cardiovascular and metabolic abnormalities in PCOS.

Polymorphisms in human muscarinic receptor subtype genes

A wide range of polymorphisms have been reported in muscarinic receptor subtype genes, mostly in M₁ and M₂ and, to a lesser extent, M₃ receptors. Most studies linking such genetic variability to phenotype have been performed for brain functions, but a more limited amount of information is also available for cardiac and airway function. Unfortunately, for none of the phenotypes under investigation a robust association with genotype has emerged. Moreover, it remains mostly unclear whether a reported association indicates a causative role of the polymorphism under investigation or merely a role as indicator of other polymorphisms affecting expression and/or function of the receptor. Also, most data on genotype-phenotype associations of muscarinic receptor subtypes are based on cross-sectional samples. Mechanistic studies linking polymorphisms to molecular, cellular, and tissue functions are largely missing. Finally, studies on a possible impact of muscarinic receptor polymorphisms on drug responsiveness are also largely missing. Thus, the field of genomics of muscarinic receptor subtypes is still in an early stage and a considerably greater number of studies will be required to judge the role of muscarinic receptor gene variability in physiology, pathophysiology, and drug treatment.

Pharmacogenomics of pediatric asthma

CONTEXT:

Asthma is a complex disease with multiple genetic and environmental factors contributing to it. A component of this complexity is a highly variable response to pharmacological therapy. Pharmacogenomics is the study of the role of genetic determinants in the variable response to therapy. A number of examples of possible pharmacogenomic approaches that may prove of value in the management of asthma are discussed below.

EVIDENCE ACQUISITION:

A search of PubMed, Google scholar, E-Medicine, BMJ and Mbase was done using the key words “pharmacogenomics of asthma”, “pharmacogenomics of β-agonist, glucocorticoids, leukotriene modifiers, theophylline, muscarinic antagonists in asthma”.

RESULTS:

Presently, there are limited examples of gene polymorphism that can influence response to asthma therapy. Polymorphisms that alter response to asthma therapy include Arg16Gly, Gln27Glu, Thr164Ile for β-agonist receptor, polymorphism of glucocorticoid receptor gene, CRHR1 variants and polymorphism of LTC4S, ALOX5. Polymorphic variants of muscarinic receptors, PDE4 and CYP450 gene variants.

CONCLUSION:

It was concluded that genetic variation can improve the response to asthma therapy. However, no gene polymorphism has been associated with consistent results in different populations. Therefore, asthma pharmacogenomic studies in different populations with a large number of subjects are required to make possible tailoring the asthma therapy according to the genetic characteristic of individual patient.

Identification of a microdeletion at the 7q33-q35 disrupting the CNTNAP2 gene in a Brazilian stuttering case

Speech and language disorders are some of the most common referral reasons to child development centers accounting for approximately 40% of cases. Stuttering is a disorder in which involuntary repetition, prolongation, or cessation of the sound precludes the flow of speech. About 5% of individuals in the general population have a stuttering problem, and about 80% of the affected children recover naturally. The causal factors of stuttering remain uncertain in most cases; studies suggest that genetic factors are responsible for 70% of the variance in liability for stuttering, whereas the remaining 30% is due to environmental effects supporting a complex cause of the disorder. The use of high-resolution genome wide array comparative genomic hybridization has proven to be a powerful strategy to narrow down candidate regions for complex disorders. We report on a case with a complex set of speech and language difficulties including stuttering who presented with a 10 Mb deletion of chromosome region 7q33-35 causing the deletion of several genes and the disruption of CNTNAP2 by deleting the first three exons of the gene. CNTNAP2 is known to be involved in the cause of language and speech disorders and autism spectrum disorder and is in the same pathway as FOXP2, another important language gene, which makes it a candidate gene for causal studies speech and language disorders such as stuttering.

Multiple genes influence BMI on chromosome 7q31-34: the NHLBI Family Heart Study

The National Heart, Lung, and Blood Institute Family Heart Study (FHS) genome-wide linkage scan identified a region of chromosome 7q31-34 with a lod score of 4.9 for BMI at D7S1804 (131.9 Mb). We report the results of linkage and association to BMI in this region for two independent FHS samples. The first sample includes 225 FHS pedigrees with evidence of linkage to 7q31-34, using 1,132 single-nucleotide polymorphisms (SNPs) and 7 microsatellites. The second represents a case-control sample (318 cases; BMI >25 and 325 controls; BMI <25) derived from unrelated FHS participants who were not part of the genome scan. The latter set was genotyped for 606 SNPs, including 37 SNPs with prior evidence for association in the linked families. Although variance components linkage analysis using only SNPs generated a peak lod score that coincided with the original linkage scan at 131.9 Mb, a conditional linkage analysis showed evidence of a second quantitative trait locus (QTL) near 143 cM influencing BMI. Three SNPs (rs161339, rs12673281, and rs1993068) located near the three genes pleiotrophin (PTN), diacylglycerol (DAG) kinase iota (DGK iota), and cholinergic receptor, muscarinic 2 (CHRM2) demonstrated significant association in both linked families (P = 0.0005, 0.002, and 0.03, respectively) and the case-control sample (P = 0.01, 0.0003, and 0.03, respectively), regardless of the genetic model tested. These findings suggest that several genes may be associated with BMI in the 7q31-34 region.

Exploring the functional role of the CHRM2 gene in human cognition: results from a dense genotyping and brain expression study

BACKGROUND

The CHRM2 gene, located on the long arm of chromosome 7 (7q31-35), is involved in neuronal excitability, synaptic plasticity and feedback regulation of acetylcholine release, and has been implicated in higher cognitive processing. The aim of this study is the identification of functional (non)coding variants underlying cognitive phenotypic variation.

METHODS

We previously reported an association between polymorphisms in the 5'UTR regions of the CHRM2 gene and intelligence.. However, no functional variants within this area have currently been identified. In order to identify the relevant functional variant(s), we conducted a denser coverage of SNPs, using two independent Dutch cohorts, consisting of a children's sample (N = 371 ss; mean age 12.4) and an adult sample (N= 391 ss; mean age 37.6). For all individuals standardized intelligence measures were available. Subsequently, we investigated genotype-dependent CHRM2 gene expression levels in the brain, to explore putative enhancer/inhibition activity exerted by variants within the muscarinic acetylcholinergic receptor.

RESULTS

Using a test of within-family association two of the previously reported variants - rs2061174, and rs324650 - were again strongly associated with intelligence (P < 0.01). A new SNP (rs2350780) showed a trend towards significance. SNP rs324650, is located within a short interspersed repeat (SINE). Although the function of short interspersed repeats remains contentious, recent research revealed potential functionality of SINE repeats in a gene-regulatory context. Gene-expression levels in post-mortem brain material, however were not dependent on rs324650 genotype.

CONCLUSION

Using a denser coverage of SNPs in the CHRM2 gene, we confirmed the 5'UTR regions to be most interesting in the context of intelligence, and ruled out other regions of this gene. Although no correlation between genomic variants and gene expression was found, it would be interesting to examine allele-specific effects on CHRM2 transcripts expression in much more detail, for example in relation to transcripts specific halve-life and their relation to LTP and memory.

Identification of a polycystic ovary syndrome susceptibility variant in fibrillin-3 and association with a metabolic phenotype

CONTEXT

Polycystic ovary syndrome (PCOS), the most common reproductive endocrine disorder of premenopausal women, is also associated with metabolic abnormalities including insulin resistance and an increased risk for diabetes mellitus. We previously mapped a PCOS susceptibility locus to chromosome 19p13.2 near the dinucleotide repeat marker D19S884.

OBJECTIVE

Our objective is to localize the chromosome 19p13.2 PCOS susceptibility locus and determine its impact on metabolic features of PCOS.

DESIGN

Resequencing and family-based association testing were used to examine the effect of sequence variation within 100 kb of D19S884 on the reproductive and metabolic phenotypes of PCOS.

SETTING

The study was conducted in an academic medical center.

SUBJECTS

Genetic analyses were performed on DNA obtained from1723 individuals in 412 families with 412 index cases and 43 affected sisters of predominantly European origin (>94%). Genotype-phenotype associations were assessed in 601 women with PCOS and 168 brothers of affected women.

RESULTS

D19S884 allele 8 (A8) within intron 55 of the fibrillin-3 (FBN3) gene showed the strongest evidence for association with PCOS of 53 variants tested (P(corrected) = 0.0037). A8 was also associated with higher levels of fasting insulin and homeostasis model assessment for insulin resistance in women with PCOS and higher fasting levels of proinsulin and proinsulin/insulin ratio in brothers.

CONCLUSIONS

These findings strongly suggest that A8 of D19S884 is the chromosome 19p13.2 PCOS susceptibility locus. The association of D19S884 with markers of insulin resistance and pancreatic beta-cell dysfunction suggests that the same variant contributes to the reproductive and metabolic abnormalities of PCOS in affected women and their brothers.

The genetics of the polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a very common endocrine disorder that has a strong genetic component and is characterized by polycystic ovaries, hyperandrogenemia, and menstrual irregularity. During the past decade, the roles of more than 70 candidate genes have been evaluated for a causal role in PCOS; however, because of genetic and phenotypic heterogeneity and underpowered studies, the results of many of these studies remain inconclusive. Here, the results of the genetic analysis of several candidate genes and gene regions-CYP11A (encoding cytochrome P450, family 11, subfamily A polypeptides), CAPN10 (encoding calpain 10), the insulin gene VNTR (variable number of tandem repeats), and D19S884 (a dinucleotide repeat marker mapping to chromosome 19p13.2)-are discussed in detail. Although past genetic studies of PCOS have yielded only modest results, resources and techniques have been assembled to remedy the major deficits of these early studies, promising that the next few years will be a very exciting and rewarding era for the genetic analysis of PCOS.

Association of CHRM2 with IQ: converging evidence for a gene influencing intelligence

The cholinergic neurotransmitter system is thought to be involved in many aspects of memory, attention, and higher cognition. In the Collaborative Study on the Genetics of Alcoholism (COGA) sample, we have previously reported linkage and association to the cholinergic muscarinic 2 receptor gene (CHRM2) on chromosome 7 with evoked EEG oscillations (Jones et al. 2004), providing evidence that this gene may be involved in human brain dynamics and cognition. In addition, a small number of genetic markers were genotyped in CHRM2 in the Minnesota Twin and Family Study (Comings et al. 2003) and a Dutch family study (Gosso et al. 2006, in press) and both research groups found evidence that this gene may be involved in intelligence. In the COGA sample, we have extensively genotyped SNPs within and flanking the CHRM2 gene. We find evidence of association with multiple SNPs across CHRM2 and Performance IQ, as measured by the Wechsler Adult Intelligence Scale-Revised (WAIS-R). These results remain significant after taking into account alcohol dependence and depression diagnoses in the sample.

Multiple promoter elements required for leukemia inhibitory factor-stimulated M2 muscarinic acetylcholine receptor promoter activity

Treatment of neuronal cells with leukemia inhibitory factor (LIF) results in increased M(2) muscarinic acetylcholine receptor promoter activity. We demonstrate here that multiple promoter elements mediate LIF stimulation of M(2) gene transcription. We identify a LIF inducible element (LIE) in the M(2) promoter with high homology to a cytokine-inducible ACTG-containing sequence in the vasoactive intestinal peptide promoter. Mutagenesis of both a STAT (signal transducers and activators of transcription) element and the LIE in the M(2) promoter is required to attenuate stimulation of M(2) promoter activity by LIF completely. Mobility shift assays indicate that a LIF-stimulated complex binds to a 70 base pair M(2) promoter fragment. Furthermore, a STAT element within this fragment can bind to LIF-stimulated nuclear STAT1 homodimers in vitro. Mutagenesis experiments show that cytokine-stimulated activation of M(2) promoter activity requires tyrosine residues on glycoprotein 130 (gp130) that are also required for both STAT1 and STAT3 activation. Dominant negative STAT1 or STAT3 can block LIF-stimulated M(2) promoter activity. Real-time RT-PCR analysis indicates that LIF-stimulated induction of M(2) mRNA is partially dependent on protein synthesis. These results show that regulation of M(2) gene transcription in neuronal cells by LIF occurs through a complex novel mechanism that is dependent on LIE, STAT and de novo protein synthesis.

Eosinophil-Mediated Cholinergic Nerve Remodeling

Eosinophils are observed to localize to cholinergic nerves in a variety of inflammatory conditions such as asthma, rhinitis, eosinophilic gastroenteritis, and inflammatory bowel disease, where they are also responsible for the induction of cell signaling. We hypothesized that a consequence of eosinophil localization to cholinergic nerves would involve a neural remodeling process. Eosinophil co-culture with cholinergic IMR32 cells led to increased expression of the M2 muscarinic receptor, with this induction being mediated via an adhesion-dependent release of eosinophil proteins, including major basic protein and nerve growth factor. Studies on the promoter sequence of the M2 receptor indicated that this induction was initiated at a transcription start site 145 kb upstream of the gene-coding region. This promoter site contains binding sites for a variety of transcription factors including SP1, AP1, and AP2. Eosinophils also induced the expression of several cholinergic genes involved in the synthesis, storage, and metabolism of acetylcholine, including the enzymes choline acetyltransferase, vesicular acetylcholine transferase, and acetylcholinesterase. The observed eosinophil-induced changes in enzyme content were associated with a reduction in intracellular neural acetylcholine but an increase in choline content, suggesting increased acetylcholine turnover and a reduction in acetylcholinesterase activity, in turn suggesting reduced catabolism of acetylcholine. Together these data suggest that eosinophil localization to cholinergic nerves induces neural remodeling, promoting a cholinergic phenotype.

Alternative promoter use and splice variation in the human histamine H1 receptor gene

Upstream gene structure and mRNA expression of the human histamine H1 receptor gene was investigated in cells relevant to the pathogenesis of asthma, (primary cultured human airway smooth muscle (HASM) cells, primary cultured human bronchial epithelial cells and bronchial epithelial cell line [BEAS2B]), and other tissues known to express histamine H1 receptors (placenta and brain). Splice variation of the 5' terminal exons gave three separate locations for novel promoters upstream of the detected transcription start sites. Further splice variants in the 5' untranslated region were also observed. Transient transfections of promoter/luciferase constructs showed these regions directed expression in HASM cells and BEAS2B cells. Polymorphism screening of the major regulatory regions identified a number of novel single-nucleotide polymorphisms. Expression of splice variants was confirmed by real-time PCR assays. Results showed one 5' terminal exon splice variant, comprising exons B/K, expressed preferentially in all tissues. Interestingly, the other 5' terminal exon splice variants showed tissue-specific patterns of expression, with variant F/K expressed negligibly (0.1%) in HASM cells, but accounting for 19.3% and 8.3% of total expression in BEAS2B cells and differentiated human bronchial epithelial cells, respectively. Splice variant A/K was second most highly expressed in differentiated human bronchial epithelial cells (23%), whereas its expression in BEAS2B and HASM cells was 1.7% and 4.4%, respectively. These data suggest the use of alternative promoters directing human H1 receptor gene expression, both within and between cell types.

Asthma pharmacogenomics

It is expected that future treatments will be preceded by genetic tests to prescribe the most effect asthma medication while lowering the risk of adverse side effects. However, it will not be necessary to describe all the genetic determinants affecting drug response to apply pharmacogenomics to asthma therapy. Whether pharmacogenomics becomes common practice may not depend on the availability of tests, but on factors such as affordability, ease of application, and ease of interpreting the results.

Variable therapeutic response in asthma: a genetic perspective

Asthma is a complex clinical syndrome with multiple genetic and environmental factors contributing to its phenotypic expression. This etiological heterogeneity adds to the complexity when addressing variation in the response to antiasthma treatment. There is regular progress in the field of asthma pharmacogenetics in determining the efficacy and potential for adverse effects of the asthma medication from a patient's genetic background. This reveals that a clinically relevant variability in response to the asthma medications may be due to genetic determinants, and refers to the polymorphisms in the genes encoding either the drug targets, or the molecular component of the downstream signal transduction pathways responsible for drug actions. The major classes of asthma therapy, β-agonists, leukotriene antagonists and inhaled corticosteroids, demonstrate wide interindividual variability. The statistical issues, such as population stratification, sample size and statistical power, are crucial factors for the identification of significant biological marker(s) for patient's response. The aim of this review is to discuss the scientific rationale and outline the genetic impact on the variability in response to different asthma medications. In conclusion, despite of new developments and recent studies in asthma pharmacogenetics, significant gaps in knowledge still remain, and several replicate studies are needed in different populations to derive firm conclusions that may help to bring pharmacotyping into clinical practice.

Functional characterization of human cysteinyl leukotriene 1 receptor gene structure

The 5-lipoxygenase pathway has been strongly implicated in the pathogenesis of chronic inflammatory disorders, such as bronchial asthma and atherosclerosis. Cysteinyl leukotrienes (cysLTs), 5-lipoxygenase pathway products, are recognized now not only as important factors in asthmatic inflammation, but also as mediators of cell trafficking and innate immune responses. To study a role of cysLTs in inflammatory reactions we have characterized the gene structure of human cysteinyl leukotriene receptor type I (cysLT(1)R). The cysLT(1)R gene consists of 5 exons that are variably spliced and a single promoter region with multiple transcription start sites. Four different cysLT(1)R transcripts were identified. RT-PCR showed dominant and wide expression of the transcript I, containing exons 1, 4, and 5, with the strongest presence in blood leukocytes, spleen, thymus, lung, and heart. The expression of cysLT(1)R is functionally regulated at the transcriptional level by IL-4 through a STAT6 response element localized to the proximal cysLT(1)R promoter region. IL-4 stimulation increased cysLT(1)R mRNA (real-time PCR) and surface protein expression (flow cytometry) in a time-dependent fashion. CysLTs (LTD(4) and LTC(4)) induced an increased production of a potent monocyte chemoattractant CCL2 (MCP-1) in IL-4-primed THP-1 cells in a dose-dependent manner. This effect was effectively inhibited by the cysLT(1)R-selective antagonist MK571 in a dose-dependent manner and only partially by a nonselective cysLT(1)R/cysLT(2)R inhibitor BAY-u9773, implying a cysLT(1)R-mediated mechanism. Thus, cysLTs signaling through cysLT(1)R might contribute to inflammatory reactions by cooperating with IL-4 in enhanced CCL2 production in human monocytic cells.

Developmental regulation and expression of the zebrafish connexin43 gene

We cloned and sequenced the zebrafish (Danio rerio) connexin43 (Cx43alpha1) gene. The predicted protein sequence shows a high degree of sequence conservation. Transcript analyses revealed multiple transcription start sites and a potential alternative transcript encoding a N-terminally truncated Cx43alpha1 protein. Maternal Cx43alpha1 transcripts were detected, with zygotic expression initiated before gastrulation. In situ hybridization revealed many Cx43alpha1 expression domains, including the notochord and brain, heart and vasculature, many resembling patterns seen in mammalian embryos. Of interest, a reporter construct under control of the mouse Cx43alpha1 promoter was observed to drive green fluorescent protein expression in zebrafish embryos in domains mimicking the native Cx43alpha1 expression pattern in fish and mice. Sequence comparison between the mouse and zebrafish Cx43alpha1 promoter sequences showed the conservation of several transcription factor motifs, which otherwise shared little overall sequence homology. The conservation of protein sequence and developmental gene regulation would suggest that Cx43alpha1 gap junctions are likely to have conserved roles in vertebrate embryonic development.

CHRM2 gene predisposes to alcohol dependence, drug dependence and affective disorders: results from an extended case–control structured association study

Cholinergic muscarinic 2 receptor (CHRM2) is implicated in memory and cognition, functions impaired in many neuropsychiatric disorders. Wang et al. [Wang, J.C., Hinrichs, A.L., Stock, H., Budde, J., Allen, R., Bertelsen, S., Kwon, J.M., Wu, W., Dick, D.M., Rice, J. et al. (2004) Evidence of common and specific genetic effects: association of the muscarinic acetylcholine receptor M2 (CHRM2) gene with alcohol dependence and major depressive syndrome. Hum. Mol. Genet., 13, 1903-1911] reported that variation in CHRM2 gene predisposed to alcohol dependence (AD) and major depressive syndrome. We examined the relationships between variation in CHRM2 and AD, drug dependence (DD) and affective disorders, using a novel extended case-control structured association (SA) method. Six markers at CHRM2 and 38 ancestry-informative markers (AIMs) were genotyped in a sample of 871 subjects, including 333 healthy controls [287 European-Americans (EAs) and 46 African-Americans (AAs)] and 538 AD and/or DD subjects (415 with AD and 346 with DD and 382 EAs and 156 AAs). The same CHRM2 markers were genotyped in a sample of 137 EA subjects with affective disorders. All of the six markers were in Hardy-Weinberg equilibrium in controls, but SNP3 (rs1824024) was in Hardy-Weinberg disequilibrium in the AD and DD groups. Using conventional case-control comparisons, some markers were nominally significantly or suggestively associated with phenotypes before or after controlling for population stratification and admixture effects, but these associations were not significant after multiple test correction. However, regression analysis identified specific alleles, genotypes, haplotypes and diplotypes that were significantly associated with risk for each disorder. We conclude that variation in CHRM2 predisposes to AD, DD and affective disorders. One haplotype block within the 5'-UTR of CHRM2 may be more important for the development of these disorders than other regions. Interaction between two specific alleles within this block and interaction between two specific diplotypes covering this block multiplicatively increased risk for AD and DD. Although interaction between these two diplotypes also increased risk for affective disorders, the magnitude of the increased risk was less than the sum of the individual risks. In addition, a specific diplotype might inversely affect risk for AD and DD and risk for affective disorders.

Pharmacogenetic approaches in the treatment of asthma

A patient's response to asthma therapy is determined by both genetic and environmental factors. In the past 10 years, we have witnessed significant progress in the field of asthma pharmacogenetics--the study of how a patient's genetic background determines the efficacy and potential for adverse effects to current asthma medication. There are now clear examples of gene polymorphisms that can influence responses to beta(2)-agonists, glucocorticosteroids, and leukotriene modifier drugs, the three main classes of medication used clinically to treat asthma. Identification of genetic polymorphism that predicts drug responses has the potential to lead to the development of new therapeutics, improve asthma management, and reduce serious episodes and hospitalizations. In this review, we discuss the current understanding of asthma pharmacogenetics, focusing on the main three classes of drugs currently used clinically.

Genetic analysis of adiponectin and obesity in Hispanic families: the IRAS Family Study

Adiponectin, coded for by the APM1 gene, is a novel adipocyte-derived hormone implicated in energy homeostasis and obesity. Several genetic studies have observed evidence of association between APM1 gene polymorphisms and features of the metabolic syndrome, such as insulin resistance and obesity. As part of a comprehensive genetic analysis of the APM1 gene, we have screened 96 unrelated individuals for polymorphisms in the promoter, coding regions, and 3'untranslated region (UTR). Three promoter single-nucleotide polymorphisms (SNPs), two rare coding SNPs (G113A and T1233C), and 13 SNPs in the 3'UTR were identified. Eighteen SNPs were genotyped in 811 Hispanic individuals from 45 families in the IRAS Family Study (IRASFS). SNPs were tested for association with six obesity quantitative traits (body mass index, waist, waist:hip ratio, subcutaneous adipose tissue, visceral adipose tissue, and visceral:subcutaneous ratio). Significant evidence of association to at least one of the obesity traits was identified in seven of the 18 SNPs (<0.001-0.05). The promoter SNP INS CA-11156 was the most consistently associated SNP and was associated significantly with all measures of obesity, except the visceral:subcutaneous ratio (P-values 0.009-0.03). Haplotype analysis supported this evidence of association, with haplotypes containing an insertion of one CA repeat at position -11156 consistently being associated with lower obesity values (P-value <0.001-0.05). The adiponectin polymorphisms, in particular those in the promoter region, thus show significant association with obesity measures in the Hispanic population. Additional studies are needed to confirm our findings and determine which polymorphism causes the functional effect.

Potential genetic influences on the response to asthma treatment

Genetic factors play a key role in determining the widely heterogeneous response to pharmacological treatment detectable among asthmatics. In particular, polymorphisms of the genes encoding relevant anti-asthma drug targets contribute significantly to such a variability. Therefore, it is very important to characterize asthmatic patient's genotypes and the related phenotypic patterns, in order to predict the individual therapeutic outcome. This pharmacogenetic approach will eventually help clinicians to optimize and personalize anti-asthma treatment, and will also provide useful information with regard to pre- and post-marketing evaluation of both effectiveness and side effects of newly introduced drugs.

Multiple promoters drive tissue-specific expression of the human M2 muscarinic acetylcholine receptor gene

Despite the wealth of information on the functional and pharmacological properties of the M2 muscarinic receptor, we know relatively little of structure and regulation of the M2 receptor gene. Here, we describe the organisation of the human M2 gene and its promoters. Four exons are present in the 5' untranslated region of the human M2 mRNA distributed over 146 kb on chromosome 7 which produce eight different splice variants in the IMR-32 neuroblastoma cell line. The unexpectedly large size of this gene indicates that transcription initiates much further upstream of the coding region than earlier studies had indicated. We present evidence that there are three distinct human M2 promoters. Analysis of endogenous transcripts revealed that promoter 2 is preferentially used in neuroblastoma cells, whereas promoter 1 in cardiac cells. All promoters are highly conserved across human, mouse, rat and pig. They contain multiple start sites and none possess a TATA-box. In addition, we describe another M2 promoter that is specific for rat. We show that GATA-4 transcription factor binds to two sites within the regulatory regions of the M2 gene using reporter gene assays, electromobility shift assays and mutational analysis.