Rare CRHR2 and GRM8 variants identified as candidate factors associated with eating disorders in Japanese patients by whole exome sequencing.

Eating disorders (EDs) are a type of psychiatric disorder characterized by pathological eating and related behavior and considered to be highly heritable. The purpose of this study was to explore rare variants expected to display biological functions associated with the etiology of EDs. We performed whole exome sequencing (WES) of affected sib-pairs corresponding to disease subtype through their lifetime and their parents. From those results, rare single nucleotide variants (SNVs) concordant with sib-pairs were extracted and estimated to be most deleterious in the examined families. Two non-synonymous SNVs located on corticotropin-releasing hormone receptor 2 (CRHR2) and glutamate metabotropic receptor 8 (GRM8) were identified as candidate disease susceptibility factors. The SNV of CRHR2 was included within the cholesterol binding motif of the transmembrane helix region, while the SNV of GRM8 was found to contribute to hydrogen bonds for an α-helix structure. CRHR2 plays important roles in the serotoninergic system of dorsal raphe nuclei, which is involved with feeding and stress-coping behavior, whereas GRM8 modulates glutamatergic neurotransmission. Moreover, GRM8 modulates glutamatergic neurotransmission, and is also considered to have effects on dopaminergic and adrenergic neurotransmission. Thus, identification of rare and deleterious variants in this study is expected to increase understanding and treatment of affected individuals. Further investigation regarding the biological function of these variants may provide an opportunity to elucidate the pathogenesis of EDs.

Establishment of a zebrafish inbred strain, M-AB, capable of regular breeding and genetic manipulation.

Inbred strains of organisms are genetically highly uniform and thus useful for life science research. We have previously reported the ongoing generation of the zebrafish IM strain from the India (IND) strain through full sib-pair mating for 16 generations. However, the IM fish laid a small number of offspring and had a short lifespan, implying the need for discreet care in breeding. Here, we report the subsequent establishment of IM strain as well as the generation of a new inbred zebrafish strain, Mishima-AB (M-AB). M-AB was derived from the *AB strain by full sib-pair mating for over 20 generations, which fulfills the general criterion for the establishment of an inbred strain. In contrast to the IM case, maintenance of the M-AB strain by sib-pair mating required almost no special handling. Genome sequencing of IM individuals from the 47th generation and M-AB individuals from the 27th generation revealed that SNP-based genomic heterogeneity across whole-genome nucleotides was 0.008% and 0.011%, respectively. These percentages were much lower than those of the parental IND (0.197%) and *AB (0.086%) strains. These results indicate that the genomes of these inbred strains were highly homogenous. We also demonstrated the successful microinjection of antisense morpholinos, CRISPR/Cas9, and foreign genes into M-AB embryos at the 1-cell stage. Overall, we report the establishment of a zebrafish inbred strain, M-AB, which is capable of regular breeding and genetic manipulation. This strain will be useful for the analysis of genetically susceptible phenotypes such as behaviors, microbiome features and drug susceptibility.

Placental Abruption and Cardiovascular Event Risk (PACER): Design, data linkage, and preliminary findings.

BACKGROUND: Obstetrical complications impact the health of mothers and offspring along the life course, resulting in an increased burden of chronic diseases. One specific complication is abruption, a life-threatening condition with consequences for cardiovascular health that remains poorly studied. OBJECTIVES: To describe the design and data linkage algorithms for the Placental Abruption and Cardiovascular Event Risk (PACER) cohort. POPULATION: All subjects who delivered in New Jersey, USA, between 1993 and 2020. DESIGN: Retrospective, population-based, birth cohort study. METHODS: We linked the vital records data of foetal deaths and live births to delivery and all subsequent hospitalisations along the life course for birthing persons and newborns. The linkage was based on a probabilistic record-matching algorithm. PRELIMINARY RESULTS: Over the 28 years of follow-up, we identified 1,877,824 birthing persons with 3,093,241 deliveries (1.1%, n = 33,058 abruption prevalence). The linkage rates for live births-hospitalisations and foetal deaths-hospitalisations were 92.4% (n = 2,842,012) and 70.7% (n = 13,796), respectively, for the maternal cohort. The corresponding linkage rate for the live births-hospitalisations for the offspring cohort was 70.3% (n = 2,160,736). The median (interquartile range) follow-up for the maternal and offspring cohorts was 15.4 (8.1, 22.4) and 14.4 (7.4, 21.0) years, respectively. We will undertake multiple imputations for missing data and develop inverse probability weights to account for selection bias owing to unlinked records. CONCLUSIONS: Pregnancy offers a unique window to study chronic diseases along the life course and efforts to identify the aetiology of abruption may provide important insights into the causes of future CVD. This project presents an unprecedented opportunity to understand how abruption may predispose women and their offspring to develop CVD complications and chronic conditions later in life.

Gene-based and pathway-based testing for rare-variant association in affected sib pairs.

Next generation sequencing technologies have made it possible to investigate the role of rare variants (RVs) in disease etiology. Because RVs associated with disease susceptibility tend to be enriched in families with affected individuals, study designs based on affected sib pairs (ASP) can be more powerful than case-control studies. We construct tests of RV-set association in ASPs for single genomic regions as well as for multiple regions. Single-region tests can efficiently detect a gene region harboring susceptibility variants, while multiple-region extensions are meant to capture signals dispersed across a biological pathway, potentially as a result of locus heterogeneity. Within ascertained ASPs, the test statistics contrast the frequencies of duplicate rare alleles (usually appearing on a shared haplotype) against frequencies of a single rare allele copy (appearing on a nonshared haplotype); we call these allelic parity tests. Incorporation of minor allele frequency estimates from reference populations can markedly improve test efficiency. Under various genetic penetrance models, application of the tests in simulated ASP data sets demonstrates good type I error properties as well as power gains over approaches that regress ASP rare allele counts on sharing state, especially in small samples. We discuss robustness of the allelic parity methods to the presence of genetic linkage, misspecification of reference population allele frequencies, sequencing error and de novo mutations, and population stratification. As proof of principle, we apply single- and multiple-region tests in a motivating study data set consisting of whole exome sequencing of sisters ascertained with early onset breast cancer.

Identification of Novel CXCL12 Genetic Polymorphisms Associated with Type 2 Diabetes Mellitus: A Chinese Sib-Pair Study.

Aims: To discover possible relationships between CXCL12 single nucleotide polymorphisms (SNPs) and type 2 diabetes mellitus (T2DM) and its risk factors. Methods: The present sib-pair study was conducted in a rural community of Beijing, China. SNPs rs2297630, rs1746048, and rs1801157 located within or nearby the CXCL12 gene were genotyped using the allele-specific polymerase chain reaction method. Haseman-Elston regression was used to investigate linkages between these SNPs and T2DM. A generalized estimating equation logistic regression model was used to discover associations between the SNPs, T2DM, and its risk factors. Results: A total of 3171 participants were recruited, comprising 2277 sib pairs. After Bonferroni correction (α = 0.016), rs2297630 was found to be significantly linked to (p = 0.003) and associated with T2DM (AA vs. GG/GA: OR = 2.26, 95% CI: 1.31-3.88, p = 0.003). There were interactions between rs2297630 and dyslipidemia (p < 0.001) and between rs1746048 and hypertension (p = 0.011). Compared to dyslipidemia-free subjects with rs2297630 GG/GA genotypes, dyslipidemia patients with rs2297630 AA had a higher risk of T2DM (OR = 4.15, 95% CI: 2.24-7.67, p < 0.001). Compared to hypertension-free subjects with rs1746048 CC genotypes, hypertension-free subjects with rs1746048 CT/TT had a decreased risk of T2DM (OR = 0.77, 95% CI: 0.60-0.99, p = 0.045). Conclusions: A novel linkage and association was found between rs2297630 and T2DM. Moreover, novel interactions were found between rs2297630 and dyslipidemia as well as rs1746048 and hypertension. These findings will help identify individuals at higher risk of developing T2DM.

Detecting Multiethnic Rare Variants.

Genome-wide association studies have identified many common genetic variants which are associated with certain diseases. The identified common variants, however, explain only a small portion of the heritability of a complex disease phenotype. The missing heritability motivated researchers to test the hypothesis that rare variants influence common diseases. Next-generation sequencing technologies have made the studies of rare variants practicable. Quite a few statistical tests have been developed for exploiting the cumulative effect of a set of rare variants on a phenotype. The best-known sequence kernel association tests (SKATs) were developed for rare variants analysis of homogeneous genomes. In this chapter, we illustrate applications of the SKATs and offer several caveats regarding them. In particular, we address how to modify the SKATs to integrate local allele ancestries and calibrate the cryptic relatedness and population structure of admixed genomes.

CDH13 Genetic Polymorphisms, Adiponectin and Ischemic Stroke: a Chinese Family-based Sib-pair Study.

OBJECTIVE: To understand the relationships between CDH13 (T-cadherin) genetic polymorphisms, adiponectin levels and ischemic stroke, and possible interactions between CDH13 polymorphisms and other risk factors. METHODS: We recruited 342 Chinese ischemic stroke sib pairs. We genotyped rs4783244 and rs7193788 on CDH13 using time-of-flight mass spectrometry genotyping technology and measured total and high-molecular weight (HMW) adiponectin levels. We investigated associations between SNPs and ischemic stroke, and interactions between SNPs and other risk factors using multi-level mixed-effects regression model. RESULTS: In individuals without ischemic stroke, CDH13 rs4783244 was associated with total adiponectin levels (per T: Coef = -0.257, P = 0.001). CDH13 rs7193788 was associated with total adiponectin levels (per A: Coef = -0.221, P = 0.001) and HMW adiponectin levels (per A: Coef = -0.163, P = 0.003). rs7193788 was significantly associated with ischemic stroke (GA/AA vs. GG: OR = 1.55, 95% CI: 1.07 to 2.24, P = 0.020) after Bonferroni correction (α = 0.025). There was an interaction between rs7193788 and diabetes (P = 0.036). Compared to diabetes-free individuals with rs7193788 GG genotype, diabetes patients with rs7193788 GA/AA genotypes had higher risks for ischemic stroke (OR = 2.64, 95% CI: 1.58-4.40, P < 0.001). CONCLUSION: CDH13 genetic polymorphisms are associated with adiponectin levels and ischemic stroke. An interaction is found between CDH13 SNP and diabetes for ischemic stroke.

Associations between homocysteine metabolism related SNPs and carotid intima-media thickness: a Chinese sib pair study.

Carotid intima-media thickness (CIMT) is a good surrogate for atherosclerosis. Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. We aim to investigate the relationships between homocysteine (Hcy) related biochemical indexes and CIMT, the associations between Hcy related SNPs and CIMT, as well as the potential gene-gene interactions. The present study recruited full siblings (186 eligible families with 424 individuals) with no history of cardiovascular events from a rural area of Beijing. We examined CIMT, intima-media thickness for common carotid artery (CCA-IMT) and carotid bifurcation, tested plasma levels for Hcy, vitamin B6 (VB6), vitamin B12 (VB12) and folic acid (FA), and genotyped 9 SNPs on MTHFR, MTR, MTRR, BHMT, SHMT1, CBS genes. Associations between SNPs and biochemical indexes and CIMT indexes were analyzed using family-based association test analysis. We used multi-level mixed-effects regression model to verify SNP-CIMT associations and to explore the potential gene-gene interactions. VB6, VB12 and FA were negatively correlated with CIMT indexes (p < 0.05). rs2851391 T allele was associated with decreased plasma VB12 levels (p = 0.036). In FABT, CBS rs2851391 was significantly associated with CCA-IMT (p = 0.021) and CIMT (p = 0.019). In multi-level mixed-effects regression model, CBS rs2851391 was positively significantly associated with CCA-IMT (Coef = 0.032, se = 0.009, raw p < 0.001) after Bonferoni correction (corrected α = 0.0056). Gene-gene interactions were found between CBS rs2851391 and BHMT rs10037045 for CCA-IMT (p = 0.011), as well as between CBS rs2851391 and MTR rs1805087 for CCA-IMT (p = 0.007) and CIMT (p = 0.022). Significant associations are found between Hcy metabolism related genetic polymorphisms, biochemical indexes and CIMT indexes. There are complex interactions between genetic polymorphisms for CCA-IMT and CIMT.

CDH13 Genetic Polymorphisms, Adiponectin and Ischemic Stroke: a Chinese Family-based Sib-pair Study / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To understand the relationships between CDH13 (T-cadherin) genetic polymorphisms, adiponectin levels and ischemic stroke, and possible interactions between CDH13 polymorphisms and other risk factors.</p><p><b>METHODS</b>We recruited 342 Chinese ischemic stroke sib pairs. We genotyped rs4783244 and rs7193788 on CDH13 using time-of-flight mass spectrometry genotyping technology and measured total and high-molecular weight (HMW) adiponectin levels. We investigated associations between SNPs and ischemic stroke, and interactions between SNPs and other risk factors using multi-level mixed-effects regression model.</p><p><b>RESULTS</b>In individuals without ischemic stroke, CDH13 rs4783244 was associated with total adiponectin levels (per T: Coef = -0.257, P = 0.001). CDH13 rs7193788 was associated with total adiponectin levels (per A: Coef = -0.221, P = 0.001) and HMW adiponectin levels (per A: Coef = -0.163, P = 0.003). rs7193788 was significantly associated with ischemic stroke (GA/AA vs. GG: OR = 1.55, 95% CI: 1.07 to 2.24, P = 0.020) after Bonferroni correction (α = 0.025). There was an interaction between rs7193788 and diabetes (P = 0.036). Compared to diabetes-free individuals with rs7193788 GG genotype, diabetes patients with rs7193788 GA/AA genotypes had higher risks for ischemic stroke (OR = 2.64, 95% CI: 1.58-4.40, P < 0.001).</p><p><b>CONCLUSION</b>CDH13 genetic polymorphisms are associated with adiponectin levels and ischemic stroke. An interaction is found between CDH13 SNP and diabetes for ischemic stroke.</p>

Construction of the Inbred Strain.

Genetically homogeneous populations such as inbred strains are valuable experimental tools in various fields of biomedical analyses. In many animals, inbred strains are established by consecutive sib-pair mating for a minimum of 20 generations. As the generation proceeds, fitness of the population reduces usually. Therefore, in order to establish inbred strains, the important point is the selection of pairs in good condition at each generation. Here, I describe the procedure and tips for generating inbred strains in zebrafish.

GCORE-sib: An efficient gene-gene interaction tool for genome-wide association studies based on discordant sib pairs.

BACKGROUND: A computationally efficient tool is required for a genome-wide gene-gene interaction analysis that tests an extremely large number of single-nucleotide polymorphism (SNP) interaction pairs in genome-wide association studies (GWAS). Current tools for GWAS interaction analysis are mainly developed for unrelated case-control samples. Relatively fewer tools for interaction analysis are available for complex disease studies with family-based design, and these tools tend to be computationally expensive. RESULTS: We developed a fast gene-gene interaction test, GCORE-sib, for discordant sib pairs and implemented the test into an efficient tool. We used simulations to demonstrate that the GCORE-sib has correct type I error rates and has comparable power to that of the regression-based interaction test. We also showed that the GCORE-sib can run more than 10 times faster than the regression-based test. Finally, the GCORE-sib was applied to a GWAS dataset with approximately 2,000 discordant sib pairs, and the GCORE-sib finished testing 19,368,078,382 pairs of SNPs within 6 days. CONCLUSIONS: An efficient gene-gene interaction tool for discordant sib pairs was developed. It will be very useful for genome-wide gene-gene interaction analysis in GWAS using discordant sib pairs. The tool can be downloaded for free at http://gcore-sib.sourceforge.net .

Investigations on Genetic Architecture of Hairy Loci in Dairy Cattle by Using Single and Whole Genome Regression Approaches.

Development of body hair is an important physiological and cellular process that leads to better adaption in tropical environments for dairy cattle. Various studies suggested a major gene and, more recently, associated genes for hairy locus in dairy cattle. Main aim of this study was to i) employ a variant of the discordant sib pair model, in which half sibs from the same sires are randomly sampled using their affection statues, ii) use various single marker regression approaches, and iii) use whole genome regression approaches to dissect genetic architecture of the hairy gene in the cattle. Whole and single genome regression approaches detected strong genomic signals from Chromosome 23. Although there is a major gene effect on hairy phenotype sourced from chromosome 23: whole genome regression approach also suggested polygenic component related with other parts of the genome. Such a result could not be obtained by any of the single marker approaches.

Childhood trauma as a risk factor for psychosis: A sib-pair study.

BACKGROUND: Childhood trauma, cannabis use and certain personality traits have been related to the development of psychosis. This study uses a sib-pair design to examine the association between childhood trauma and psychosis controlling for cannabis use and neuroticism. METHODS: We evaluated 60 patient-sibling pairs, conformed by patients with functional psychosis in the first five years of their illness matched with a non-psychotic sibling. In univariate analyses, patients and siblings were compared with McNemar tests and paired-sample t tests. A conditional logistic regression model of the risk of developing psychosis was built. The dependent variable of this model was the patient-sibling status (patient = 1, sibling = 0). RESULTS: After controlling for cannabis use and neuroticism, the odds of suffering psychosis for subjects who experienced a childhood trauma were 7.3 times higher than the odds for subjects who did not experience a childhood trauma [95% CI, (1.06-50.01); P = 0.04]. Also, after controlling for experiencing childhood trauma and neuroticism, subjects who were heavy cannabis users had odds of suffering psychosis that were 6.4 times higher than the odds of the remaining subjects [95% CI, (1.2-35.2); P = 0.03]. CONCLUSION: Both childhood trauma and cannabis use were significantly associated with an increased risk of suffering functional psychosis. A neurotic personality also contributed independently to this risk. These findings might help improve the prevention of psychosis and the development of specific treatment strategies on this specific population.

Evaluation of the influence of alcohol dehydrogenase polymorphisms on alcohol elimination rates in African Americans.

INTRODUCTION: The relationship between alcohol dehydrogenase (ADH) polymorphisms and alcohol use disorders in populations of African descent has not been clearly established. This study examined the effect of ADH1B polymorphisms on alcohol metabolism and subjective response, following intravenous (IV) alcohol administration, and the influence of gender, recent drinking history, and family history of alcoholism (FHA), in nondependent African American drinkers. MATERIALS: The sample included eighty-seven 21- to 35-year-old, light social drinkers of African descent. Participants included 39 sib pairs, 2 sibships with 3 siblings each, and 3 individuals who were not part of a sibship. Participants received infusions via the use of the clamp method that refers to the goal of controlling breath alcohol concentration in 2 randomized sessions at 0.06 g% ethanol and 0 mg% (placebo), and a battery of subjective scales at predefined time points. Dependent measures included alcohol elimination rates (AERs), alcohol disappearance rates (ADRs), subjective measures peak scores, and area under the curve. General linear model and mixed models were performed to examine the relationship between ADH1B genotype, dependent measures, and influence of covariates. RESULTS: Participants with ADH1B1/1 genotypes showed higher number of drinks (p = 0.023) and drinks per drinking day (p = 0.009) compared with the persons with ADH1B1/3 genotype. AER (adjusted for body weight) was higher in ADH1B*1 homozygotes (p = 0.045) compared with ADH1B1/3 heterozygotes. ADR differed significantly between males and females (p = 0.002), regardless of body weight (p = 0.004) and lean body mass (p < 0.001) adjustments. Although a few subjective measures differed across genotype, all measures were higher in alcohol sessions compared with placebo sessions (p < 0.001). These observations were mediated by drinks per drinking day, gender, and FHA. CONCLUSIONS: ADH1B polymorphism had a marginal effect on alcohol pharmacokinetics following IV alcohol administration in nondependent drinkers of African descent. Session (alcohol vs. placebo) and ADH1B genotype did, however, influence subjective response to alcohol with some variation by gender, FHA, and drinks per drinking day.

Confounding with familial determinants affects the association between mode of delivery and childhood asthma medication - a national cohort study.

BACKGROUND: Mode of delivery may affect the risk of asthma but the findings have not been consistent and factors shared by siblings may confound the associations in previous studies. METHODS: The association between mode of delivery and dispensed inhaled corticosteroid (ICS) (a marker of asthma) was examined in a register based national cohort (n=199 837). A cohort analysis of all first born children aged 2-5 and 6-9 years was performed. An age-matched sibling-pair analysis was also performed to account for shared genetic and environmental risk factors. RESULTS: Analyses of first-borns demonstrated that elective caesarean section was associated with an increased risk of dispensed ICS in both 2-5 (adjusted odds ratio (aOR)=1.19, 95% confidence interval (CI) 1.09-1.29) and 6-9 (aOR=1.21, 1.09-1.34) age groups. In the sibling-pair analysis, the increased risk associated with elective caesarean section was confirmed in 2-5 year olds (aOR=1.22, 1.05-1.43) but not in 6-9 year olds (aOR=1.06, 0.78-1.44). Emergency caesarean section and vacuum extraction had some association with dispensed ICS in the analyses of first-borns but these associations were not confirmed in the sibling-pair analyses. CONCLUSIONS: Confounding by familial factors affects the association between mode of delivery and dispensed ICS. Despite this confounding, there was some evidence that elective caesarean section contributed to a modestly increased risk of dispensed ICS but only up to five years of age.

Generation of highly homogeneous strains of zebrafish through full sib-pair mating.

Genetically homogeneous populations, such as inbred strains, are powerful experimental tools that are ideally suited for studying immunology, cancer, and genetics of complex traits. The zebrafish, Danio rerio, has been underutilized in these research areas because homogeneous strains of experimental fish have not been available in tractable condition. Here, we attempted to inbreed two zebrafish wild-type strains, Tübingen and India, through full sib-pair mating. Although the inbred Tübingen strain failed to thrive and was lost after 13 generations, an inbred India strain (IM) has been maintained successfully. The IM strain has endured 16 generations of inbreeding and has maintained a healthy condition. Two additional strains, IM12m and IM14m, were established as closed colonies from the branches of the IM strain. Genotype analyses using genetic markers revealed a dramatic decrease in polymorphisms (62% dropped to 5%) in both IM (generation 14) and the two closed colonies. This indicates a high level of homogeneity in these strains. Furthermore, scale transplantations between individuals within each strain were successful. These data suggest that extremely homogeneous zebrafish strains have been established, thereby creating a valuable resource for practical application.

Linkage analysis between gene marker of chromosome 11q13, and skin reactivity to common inhalant allergens and bronchial responsiveness in sib-pairs with probands of asthmatic children / 천식및알레르기

BACKGROUND: Increased IgE antibody responses to inhalant allergens and bronchial hyperresponsiveness are important phenotypes in development of asthma. Although heredity reported to be important in expression of these phenotypes in twin and family studies, genetic factor(s) controlling these phenotypes is unknown. OBJECTIVE: To evaluate whether genetic factor in chromosome 11q13 may control the expression of IgE responses to common inhalant allergens and bronchial hyperresponsiveness, linkage analysis between these phenotypes and gene marker of chromosome 11q13 was investigated. MATERIALS AND METHODS: The phenotyping and genotyping using microsatellite marker (D11S97) were performed in 77 probands with bronchial asthma and 80 their sibs. The linkage analysis between these phenotypes and the genotype was evaluated by affected or quantitative trait locus (QTL) sib-pair analysis. RESULTS: Positive skin test responses to inhalant allergens were 55/77(71.4%) in probands and 44/79(55.6%) in sibs, respectively. Positive bronchial provocation test responses to methacholine were 27/61(44.3%) in sibs, geometric mean of PC20-methacholine were 5.2 mg/ ml in probands and 39.4 mg/ml in sibs, respectively, and slope of dose response curve(mean+- SE, %/mg/ml) were 11.3 +- 3.22 in probands and 1.97 +- 0.5 in sibs, respectively. Of 34 sib-pairs with positive skin test responses to allergens, two D11S97 alleles were shared by 21(61.8% ) sib -pairs, one allele by 11(32.3% ) sib-pairs, and no identical allele by two(5.9% ) sib-pairs. In affected sib-pairs, sharing rate of the alleles was 77.9%, which indicates linkage of the phenotype and genotype(p<0.001). Of 25 sib-pairs with bronchial hyperresponsiveness to methacholine, two D11S97 alleles were shared by seven(28%) sib-pairs, one allele by 11(44%) sib-pairs, and no identical allele by seven(28% ) sib-pairs. In affected sib-pairs, sharing rate of the alleles was 50%, which indicates no linkage between the phenotype and genotype(p) 0.05). Differences of geometric value(mean +- SE) of PC-methacholine and slope of dose response curve(mean +- SE, %/mg/ml) were 1.11+- 0.17 and 8.33+- 3.35 in sib-pairs sharing two alleles, respectively, 0.99 +- 0.14 and 14.27+-5.75 in sib-pairs sharing one allele, respectively, and 0.57+-0.13 and 3.64+-1.62 in sib-pairs sharing no allele, respectively. There was no difference of the above values among the three groups. CONCLUSION: The expression of skin reactivity to common inhalant allergens was linked to gene marker of chromosome 11q13, not with bronchial responsiveness to methacholine.