Further evidence for the role of genes on chromosome 2 and chromosome 5 in the inheritance of pulmonary function

The Effect of Ancestry and Genetic Variation on Lung Function Predictions: What Is "Normal" Lung Function in Diverse Human Populations?

Lung function measures are an invaluable screening test for respiratory health and have been associated with the morbidity and mortality related to different airway disease as well as all-cause mortality. Currently, reference values for spirometric measurements are obtained using equations derived from individual ethnic or racial groups. The rapid expansion of more racially and ethnically diverse populations will challenge current race-based lung function reference equations. Recent international general population studies and ancestry-based genetic studies have found that ancestry and genetic variation are determinants of lung function and have suggested a role for genetic ancestry or gene variants in future lung function reference equations. In this review, we discuss the potential limitations of current lung function reference equations in a global society which is becoming more ethnically, racially, and, thus, genetically diverse. We also focus on how an individual's ancestral background or genetic profile could provide the basis for more accurate, personalized predictions of an individual's baseline lung function.

Genome-wide association study of lung function decline in adults with and without asthma

BACKGROUND

Genome-wide association studies have identified determinants of chronic obstructive pulmonary disease, asthma, and lung function level; however, none have addressed decline in lung function.

OBJECTIVE

We conducted the first genome-wide association study on the age-related decrease in FEV(1) and its ratio to forced vital capacity (FVC) stratified a priori by asthma status.

METHODS

Discovery cohorts included adults of European ancestry (1,441 asthmatic and 2,677 nonasthmatic participants: the Epidemiological Study on the Genetics and Environment of Asthma, the Swiss Cohort Study on Air Pollution and Lung and Heart Disease in Adults, and the European Community Respiratory Health Survey). The associations of FEV(1) and FEV(1)/FVC ratio decrease with 2.5 million single nucleotide polymorphisms (SNPs) were estimated. Thirty loci were followed up by in silico replication (1,160 asthmatic and 10,858 nonasthmatic participants: Atherosclerosis Risk in Communities, the Framingham Heart Study, the British 1958 Birth Cohort, and the Dutch Asthma Study).

RESULTS

Main signals identified differed between asthmatic and nonasthmatic participants. None of the SNPs reached genome-wide significance. The association between the height-related gene DLEU7 and FEV(1) decrease suggested for nonasthmatic participants in the discovery phase was replicated (discovery, P = 4.8 × 10(-6); replication, P = .03), and additional sensitivity analyses point to a relation to growth. The top ranking signal, TUSC3, which is associated with FEV(1)/FVC ratio decrease in asthmatic participants (P = 5.3 × 10(-8)), did not replicate. SNPs previously associated with cross-sectional lung function were not prominently associated with decline.

CONCLUSIONS

Genetic heterogeneity of lung function might be extensive. Our results suggest that genetic determinants of longitudinal and cross-sectional lung function differ and vary by asthma status.

C21orf91 genotypes correlate with herpes simplex labialis (cold sore) frequency: description of a cold sore susceptibility gene

BACKGROUND

Herpes simplex virus type 1 (HSV-1) infects >70% of the United States population. We identified a 3-megabase region on human chromosome 21 containing 6 candidate genes associated with herpes simplex labialis (HSL, "cold sores").

METHODS

We conducted single nucleotide polymorphism (SNP) scans of the chromosome 21 region to define which of 6 possible candidate genes were associated with cold sore frequency. We obtained the annual HSL frequency for 355 HSV-1 seropositive individuals and determined the individual genotypes by SNPlex for linkage analysis and parental transmission disequilibrium testing (ParenTDT).

RESULTS

Two-point linkage analysis showed positive linkage between cold sore frequency and 2 SNPs within the C21orf91 region, 1 of which is nonsynonymous. ParenTDT analysis revealed a strong association between another C21orf91 SNP, predicted to lie in the 3' untranslated region, and frequent HSL (P = .0047). C21orf 91 is a predicted open reading frame of unknown function that encodes a cytosolic protein.

CONCLUSIONS

We evaluated candidate genes in the cold sore susceptibility region using fine mapping with 45 SNP markers. 2 complementary techniques identified C21orf91 as a gene of interest for susceptibility to HSL. We propose that C21orf91 be designated the Cold Sore Susceptibility Gene-1 (CSSG1).

Association of SERPINE2 with asthma

BACKGROUND

The "Dutch hypothesis" suggests that asthma and COPD have common genetic determinants. The serpin peptidase inhibitor, clade E (nexin, plasminogen activator inhibitor type 1), member 2 (SERPINE2) gene previously has been associated with COPD. We sought to determine whether SERPINE2 is associated with asthma and asthma-related phenotypes.

METHODS

We measured the association of 39 SERPINE2 single-nucleotide polymorphisms (SNPs) with asthma-related phenotypes in 655 parent-child trios from the Childhood Asthma Management Program (CAMP), and we measured the association of 19 SERPINE2 SNPs with asthma in a case-control design of 359 CAMP probands and 846 population control subjects. We attempted to replicate primary asthma-related phenotype findings in one independent population and primary asthma affection status findings in two independent populations. We compared association results with CAMP proband expression quantitative trait loci.

RESULTS

Nine of 39 SNPs had P < .05 for at least one phenotype in CAMP, and two of these replicated in an independent population of 426 people with childhood asthma. Six of 19 SNPs had P < .05 for association with asthma in CAMP/Illumina. None of these replicated in two independent populations. The expression quantitative trait loci revealed that five SNPs associated with asthma in CAMP/Illumina and one SNP associated with FEV(1) in CAMP are strongly correlated with SERPINE2 expression levels. Comparison of results to previous COPD studies identified five SNPs associated with both asthma- and COPD-related phenotypes.

CONCLUSIONS

Our results weakly support SERPINE2 as a Dutch hypothesis candidate gene through nominally significant associations with asthma and related traits. Further study of SERPINE2 is necessary to verify its involvement in asthma and COPD.

A chronic obstructive pulmonary disease related signature in squamous cell lung cancer

The epidemiological relationship between squamous cell lung cancer (SCC) and chronic obstructive pulmonary disease (COPD), both smoking-related diseases, suggests that they have also a genetic basis. We compared 35 SCC patients with and without COPD with whole-genome gene expression profiles of laser microdissected tissue. Validation of differential expression was performed for 25 genes using quantitative (q)RT-PCR. Subsequently, we performed array-based CGH on the same tumor samples. We found that 374 probes were differentially expressed in SCC from patients with and without COPD. Forty-four probes were derived from genes with mitochondrial functions and 34 probes were located on 5q. All these probes showed a lower expression level in SCC from non-COPD patients. For a random selection of 25 mitochondrial and 5q genes, we confirmed the differential expression by qRT-PCR. Loss of 3p, 5q and 9p was observed, via array-CGH, to be more frequent in SCC from non-COPD patients as compared to SCC from COPD patients. Combination of chromosomal aberrations and the location of the differentially expressed genes showed significant association for loss of the 5q31.2-31.3 region and reduced expression of the 5q genes. In conclusion, a more frequent loss of 5q and a low expression of genes located on 5q in SCC tumors of non-COPD patients compared to tumors from COPD patients was identified suggesting that different oncogenetic pathways are operational in patients with and without COPD.

CTLA4 and CD86 gene polymorphisms and susceptibility to chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) may be related to chronic inflammation and immune-mediated conditions, and its pathogenesis involves T-cell activation and proliferation. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and costimulatory molecules (CD80/CD86) genes are important mediators of T-cell activation in the immune response. The aim of this study was to investigate whether +2379G/C (rs17281995) and +1057G/A (rs1129055) in CD86 and -318C/T (rs5742909) and +49A/G (rs231775) in CTLA-4 genes single nucleotide polymorphisms (SNPs) are associated with COPD in a Chinese population. The four polymorphisms were identified in 396 COPD patients and 400 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The frequency of the T allele of the -318C/T in CTLA-4 and the A allele of the +1057G/A in CD86 polymorphisms showed significant association with COPD when compared with controls (T allele: p < 0.0001; A allele: p = 0.009). Comparison of genotype frequencies showed that -318CT, +1057GA, and +1057AA genotype was overrepresented in the COPD group, respectively (-318CT: 50.8% vs 28.5%, p < 0.0001; +1057GA: 58.6% vs 54.2%, p = 0.002; +1057AA: 30.1% vs 25.8%, p = 0.002). However, we failed to find any association between the four SNPs and COPD when cases were classified by smoking status or clinical stages (p > 0.05). The results indicate that the polymorphisms of CTLA-4 (-318C/T) and CD86 (+1057G/A) may be important genetic factor associated with risk or protection for COPD in Chinese population.

Multistudy fine mapping of chromosome 2q identifies XRCC5 as a chronic obstructive pulmonary disease susceptibility gene

RATIONALE

Several family-based studies have identified genetic linkage for lung function and airflow obstruction to chromosome 2q.

OBJECTIVES

We hypothesized that merging results of high-resolution single nucleotide polymorphism (SNP) mapping in four separate populations would lead to the identification of chronic obstructive pulmonary disease (COPD) susceptibility genes on chromosome 2q.

METHODS

Within the chromosome 2q linkage region, 2,843 SNPs were genotyped in 806 COPD cases and 779 control subjects from Norway, and 2,484 SNPs were genotyped in 309 patients with severe COPD from the National Emphysema Treatment Trial and 330 community control subjects. Significant associations from the combined results across the two case-control studies were followed up in 1,839 individuals from 603 families from the International COPD Genetics Network (ICGN) and in 949 individuals from 127 families in the Boston Early-Onset COPD Study.

MEASUREMENTS AND MAIN RESULTS

Merging the results of the two case-control analyses, 14 of the 790 overlapping SNPs had a combined P < 0.01. Two of these 14 SNPs were consistently associated with COPD in the ICGN families. The association with one SNP, located in the gene XRCC5, was replicated in the Boston Early-Onset COPD Study, with a combined P = 2.51 x 10(-5) across the four studies, which remains significant when adjusted for multiple testing (P = 0.02). Genotype imputation confirmed the association with SNPs in XRCC5.

CONCLUSIONS

By combining data from COPD genetic association studies conducted in four independent patient samples, we have identified XRCC5, an ATP-dependent DNA helicase, as a potential COPD susceptibility gene.

SERPINE2 polymorphisms and chronic obstructive pulmonary disease

A number of genome-wide linkage analyses have identified the 2q33.3-2q37.2 region as most likely to contain the genes that contribute to the susceptibility to chronic obstructive pulmonary disease (COPD). It was hypothesized that the SERPINE2 gene, which is one of the genes located at the 2q33.3-2q37.2 region, may act as a low-penetrance susceptibility gene for COPD. To test this hypothesis, the association of four SERPINE2 single nucleotide polymorphisms (SNPs; rs16865421A>G, rs7583463A>C, rs729631C>G, and rs6734100C>G) with the risk of COPD was investigated in a case-control study of 311 COPD patients and 386 controls. The SNP rs16865421 was associated with a significantly decreased risk of COPD in a dominant model for the polymorphic allele (adjusted odds ratio [OR]=0.66, 95% confidence interval [CI]=0.45-0.97, P=0.03). In haplotype analysis, the GACC haplotype carrying the polymorphic allele at the rs16865421 was associated with a significantly decreased risk of COPD when compared to the AACC haplotype (adjusted OR=0.58, 95% CI=0.38-0.89, P=0.01), and this effect was evident in younger individuals (adjusted OR=0.30, 95% CI=0.14-0.64, P=0.002). This study suggests that the SERPINE2 gene contributes to the susceptibility to COPD.

Genetics of chronic obstructive pulmonary disease: a succinct review, future avenues and prospective clinical applications

Chronic obstructive pulmonary disease (COPD) is influenced by genetic and environmental factors. A large number of candidate gene-association studies and genome-wide linkage scans have been conducted to elucidate the genetic architecture underlying this disease. The compilation of these studies clearly revealed the complex genetic nature of COPD. Multiple genes acting on specific environmental backgrounds are likely to be the tenet of this multifactorial disorder. Encouragingly, reproducible susceptibility genes, such as SERPINE2, were recently identified. Advances in genomic research offer unprecedented capabilities to interrogate the human genome and are likely to accelerate the discovery of new genes. A comprehensive catalogue of genes implicated in the pathogenesis of COPD has great potential to lead to the development of new therapies and explain interindividual response to treatment.

Significant evidence for linkage to chromosome 5q13 in a genome-wide scan for asthma in an extended pedigree resource

Asthma is a multifactorial disease with undetermined genetic factors. We performed a genome-wide scan to identify predisposition loci for asthma. The asthma phenotype consisted of physician-confirmed presence or absence of asthma symptoms. We analyzed 81 extended Utah pedigrees ranging from three to six generations, including 742 affected individuals, ranging from 2 to 40 per pedigree. We performed parametric multipoint linkage analyses with dominant and recessive models. Our analysis revealed genome-wide significant evidence of linkage to region 5q13 (log of the odds ratio (LOD)=3.8, recessive model), and suggestive evidence for linkage to region 6p21 (LOD=2.1, dominant model). Both the 5q13 and 6p21 regions indicated in these analyses have been previously identified as regions of interest in other genome-wide scans for asthma-related phenotypes. The evidence of linkage at the 5q13 region represents the first significant evidence for linkage on a genome-wide basis for this locus. Linked pedigrees localize the region to approximately between 92.3-105.5 Mb.

Genetic associations with hypoxemia and pulmonary arterial pressure in COPD

BACKGROUND

Hypoxemia, hypercarbia, and pulmonary arterial hypertension are known complications of advanced COPD. We sought to identify genetic polymorphisms associated with these traits in a population of patients with severe COPD from the National Emphysema Treatment Trial (NETT).

METHODS

In 389 participants from the NETT Genetics Ancillary Study, single-nucleotide polymorphisms (SNPs) were genotyped in five candidate genes previously associated with COPD susceptibility (EPHX1, SERPINE2, SFTPB, TGFB1, and GSTP1). Linear regression models were used to test for associations among these SNPs and three quantitative COPD-related traits (Pao(2), Paco(2), and pulmonary artery systolic pressure). Genes associated with hypoxemia were tested for replication in probands from the Boston Early-Onset COPD Study.

RESULTS

In the NETT Genetics Ancillary Study population, SNPs in microsomal epoxide hydrolase (EPHX1) [p = 0.01 to 0.04] and serpin peptidase inhibitor, clade E, member 2 (SERPINE2) [p = 0.04 to 0.008] were associated with hypoxemia. One SNP within surfactant protein B (SFTPB) was associated with pulmonary artery systolic pressure (p = 0.01). In probands from the Boston Early-Onset COPD Study, SNPs in EPHX1 and in SERPINE2 were associated with the requirement for supplemental oxygen.

CONCLUSIONS

In participants with severe COPD, SNPs in EPHX1 and SERPINE2 were associated with hypoxemia in two separate study populations, and SNPs from SFTPB were associated with pulmonary artery pressure in the NETT participants.

National Emphysema Treatment Trial state of the art: genetics of emphysema

Although a hereditary contribution to emphysema has been long suspected, severe alpha1-antitrypsin deficiency remains the only conclusively proven genetic risk factor for chronic obstructive pulmonary disease (COPD). Recently, genome-wide linkage analysis has led to the identification of two promising candidate genes for COPD: TGFB1 and SERPINE2. Like multiple other COPD candidate gene associations, even these positionally identified genes have not been universally replicated across all studies. Differences in phenotype definition may contribute to nonreplication in genetic studies of heterogeneous disorders such as COPD. The use of precisely measured phenotypes, including emphysema quantification on high-resolution chest computed tomography scans, has aided in the discovery of additional genes for clinically relevant COPD-related traits. The use of computed tomography scans to assess emphysema and airway disease as well as newer genetic technologies, including gene expression microarrays and genome-wide association studies, has great potential to detect novel genes affecting COPD susceptibility, severity, and response to treatment.

SLC11A1 polymorphisms are associated with the risk of chronic obstructive pulmonary disease in a Korean population

The solute carrier family 11 member 1 (SLC11A1) protein plays important roles in macrophage activation and displays pleiotropic effects on various macrophage functions, including the regulation of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and oxidative burst. Considering the important roles of macrophage in the pathogenesis of chronic obstructive pulmonary disease (COPD), we hypothesized that the SLC11A1 gene may act as a low-penetrance susceptibility gene for COPD. To test this hypothesis, we first examined the frequencies of 12 candidate polymorphisms in the SLC11A1 gene in 27 healthy Korean individuals, and then genotyped 3 haplotype-tagging polymorphisms [IVS4 + 14G > C (rs3731865), D543 N (rs17235409), and (*)86A > G (rs1059823)] in 83 COPD patients and 203 healthy controls. Individuals with at least one variant allele of the D543 N and (*)86A > G polymorphisms were at a significantly increased risk for COPD compared with carriers with each homozygous wild-type allele [adjusted odds ratio (OR) = 2.23, 95% confidence interval (CI) = 1.24-4.02, P = 0.007; and adjusted OR = 1.92, 95% CI = 1.10-3.35, P = 0.022, respectively]. Consistent with the findings of the genotyping analysis, the 122 haplotype carrying both the 543 N and (*)86G alleles was associated with a significantly increased risk for COPD compared with the 111 haplotype with the 542D and (*)86A alleles (adjusted OR = 2.05, 95% CI = 1.19-3.51, P = 0.009 and Bonferroni corrected P = 0.027). These findings suggest that the SLC11A1 polymorphisms could be used as markers for genetic susceptibility to COPD. However, further studies with large numbers of subjects are needed to confirm our findings.

Identification of a herpes simplex labialis susceptibility region on human chromosome 21

BACKGROUND

Most of the United States population is infected with either herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2, or both. Reactivations of HSV-1 infection cause herpes simplex labialis (HSL; cold sores or fever blisters), which is the most common recurring viral infection in humans.

METHODS

To investigate the possibility of a human genetic component conferring resistance or susceptibility to cold sores (i.e., a HSL susceptibility gene), we conducted a genetic linkage analysis that included serotyping and phenotyping 421 individuals from 39 families enrolled in the Utah Genetic Reference Project.

RESULTS

Linkage analysis identified a 2.5-Mb nonrecombinant region of interest on the long arm of human chromosome 21, with a multipoint logarithm of odds score of 3.9 noted near marker abmc65 (D21S409). Nonparametric linkage analysis of the data also provided strong evidence for linkage (P = .0005). This region of human chromosome 21 contains 6 candidate genes for herpes susceptibility.

CONCLUSIONS

The development of frequent cold sores is associated with a region on the long arm of human chromosome 21. This region contains several candidate genes that could influence the frequency of outbreaks of HSL.

The SERPINE2 gene is associated with chronic obstructive pulmonary disease in two large populations

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a complex disease influenced by multiple genes and environmental factors. A region on chromosome 2q has been shown to be linked to COPD. A positional candidate gene from the chromosome 2q region SERPINE2 (Serpin peptidase inhibitor, clade E [nexin, plasminogen activator inhibitor type 1], member 2), was previously evaluated as a susceptibility gene for COPD in two association studies, but the results were contradictory.

OBJECTIVES

To identify the relationship between SERPINE2 polymorphisms and COPD-related phenotypes using family-based and case-control association studies.

METHODS

In the present study, we genotyped 25 single nucleotide polymorphisms (SNPs) from SERPINE2 and analyzed qualitative and quantitative COPD phenotypes in 635 pedigrees with 1,910 individuals and an independent case-control population that included 973 COPD cases and 956 control subjects. The family data were analyzed using family-based association tests. The case-control data were analyzed using logistic regression and linear models.

MEASUREMENTS AND MAIN RESULTS

Six SNPs demonstrated significant associations with COPD phenotypes in the family-based association analysis (0.0016<or=p<or=0.042). Five of these SNPs demonstrated replicated associations in the case-control analysis (0.021<or=p<or=0.031). In addition, the results of haplotype analyses supported the results from single SNP analyses.

CONCLUSIONS

These data provide further support for SERPINE2 as a COPD susceptibility gene.

Genome-wide linkage analysis of pulmonary function in families of children with asthma in Costa Rica

BACKGROUND

Although asthma is highly prevalent among certain Hispanic subgroups, genetic determinants of asthma and asthma-related traits have not been conclusively identified in Hispanic populations. A study was undertaken to identify genomic regions containing susceptibility loci for pulmonary function and bronchodilator responsiveness (BDR) in Costa Ricans.

METHODS

Eight extended pedigrees were ascertained through schoolchildren with asthma in the Central Valley of Costa Rica. Short tandem repeat (STR) markers were genotyped throughout the genome at an average spacing of 8.2 cM. Multipoint variance component linkage analyses of forced expiratory volume in 1 second (FEV(1)) and FEV(1)/ forced vital capacity (FVC; both pre-bronchodilator and post-bronchodilator) and BDR were performed in these eight families (pre-bronchodilator spirometry, n = 640; post-bronchodilator spirometry and BDR, n = 624). Nine additional STR markers were genotyped on chromosome 7. Secondary analyses were repeated after stratification by cigarette smoking.

RESULTS

Among all subjects, the highest logarithm of the odds of linkage (LOD) score for FEV(1) (post-bronchodilator) was found on chromosome 7q34-35 (LOD = 2.45, including the additional markers). The highest LOD scores for FEV(1)/FVC (pre-bronchodilator) and BDR were found on chromosomes 2q (LOD = 1.53) and 9p (LOD = 1.53), respectively. Among former and current smokers there was near-significant evidence of linkage to FEV(1)/FVC (post-bronchodilator) on chromosome 5p (LOD = 3.27) and suggestive evidence of linkage to FEV(1) on chromosomes 3q (pre-bronchodilator, LOD = 2.74) and 4q (post-bronchodilator, LOD = 2.66).

CONCLUSIONS

In eight families of children with asthma in Costa Rica, there is suggestive evidence of linkage to FEV(1) on chromosome 7q34-35. In these families, FEV(1)/FVC may be influenced by an interaction between cigarette smoking and a locus (loci) on chromosome 5p.

Progress in chronic obstructive pulmonary disease genetics

Familial aggregation of chronic obstructive pulmonary disease (COPD) has been demonstrated, suggesting that genetic factors likely influence the variable development of chronic airflow obstruction in response to smoking. A variety of approaches have been used to identify novel COPD susceptibility genes, including association studies, linkage analysis, and rare variant analysis. Future directions for COPD research include genomewide association studies and animal model genetic studies.

The SERPINE2 gene is associated with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex human disease likely influenced by multiple genes, cigarette smoking, and gene-by-smoking interactions, but only severe alpha 1-antitrypsin deficiency is a proven genetic risk factor for COPD. Prior linkage analyses in the Boston Early-Onset COPD Study have demonstrated significant linkage to a key intermediate phenotype of COPD on chromosome 2q. We integrated results from murine lung development and human COPD gene-expression microarray studies with human COPD linkage results on chromosome 2q to prioritize candidate-gene selection, thus identifying SERPINE2 as a positional candidate susceptibility gene for COPD. Immunohistochemistry demonstrated expression of serpine2 protein in mouse and human adult lung tissue. In family-based association testing of 127 severe, early-onset COPD pedigrees from the Boston Early-Onset COPD Study, we observed significant association with COPD phenotypes and 18 single-nucleotide polymorphisms (SNPs) in the SERPINE2 gene. Association of five of these SNPs with COPD was replicated in a case-control analysis, with cases from the National Emphysema Treatment Trial and controls from the Normative Aging Study. Family-based and case-control haplotype analyses supported similar regions of association within the SERPINE2 gene. When significantly associated SNPs in these haplotypic regions were included as covariates in linkage models, LOD score attenuation was observed most markedly in a smokers-only linkage model (LOD 4.41, attenuated to 1.74). After the integration of murine and human microarray data to inform candidate-gene selection, we observed significant family-based association and independent replication of association in a case-control study, suggesting that SERPINE2 is a COPD-susceptibility gene and is likely influenced by gene-by-smoking interaction.

Genomewide screen for pulmonary function in 200 families ascertained for asthma

Changes in pulmonary function are important in determining asthma outcome. Genetic factors may influence airway obstruction in asthma. We performed a genomewide screen in 200 families of probands objectively diagnosed with asthma in the 1960s to identify chromosomal regions related to changes in pre- and postbronchodilator lung function (FEV1, VC, and FEV1%VC) and assess influences of early-life smoke exposure. Smoking (pack-years), age, sex, and height were covariates in variance component analyses. Significant evidence for linkage of pre- and postbronchodilator FEV1%VC was obtained for chromosome 2q32 (LOD,4.9, increasing to 6.03 with additional fine-mapping markers, and 3.2, respectively). Linkage existed for chromosome 5q for pre- and postbronchodilator VC (likelihood of disease [LOD], 1.8 and 2.6, respectively). Results for pre- and postbronchodilator FEV1 were less significant (LOD, 1.5 and 1.6, chromosomes 11p and 10q, respectively). Results were not affected by passive smoke exposure. There is significant evidence for linkage of FEV1%VC to chromosome 2q32 in families of probands with asthma, 35 cM proximal from linkage previously observed in families of probands with early-onset chronic obstructive pulmonary disease. Thus, there may be multiple genes on chromosome 2q that are important in determining presence and degree of airflow limitation in families ascertained for obstructive airway disease.

Genomewide Linkage Analysis Identifies Novel Genetic Loci for Lung Function in Mice

RATIONALE

Pulmonary function, including lung volumes and compliance, may be genetically determined, but few genetic polymorphisms have been identified that control these traits. We used an experimental approach and performed the first whole genome scan for pulmonary function in mice.

OBJECTIVES AND METHODS

To identify novel chromosomal regions contributing to lung function, quantitative trait locus linkage analysis was applied in N(2) backcross and F(2) intercross mice derived from two inbred strains-C3H/HeJ and JF1/Msf-with extremely divergent phenotypes.

MAIN RESULTS

Significant linkages to total lung capacity with LOD (logarithm of the odds) scores up to 6.0 were detected on chromosomes 15 and 17, to dead space volume and lung compliance on chromosomes 5 and 15 (LOD scores higher than 4.0), to lung compliance also on chromosome 19 (LOD score of 5.8), and to diffusing capacity on chromosomes 15 and 17 (LOD scores up to 5.0). The region of interest on chromosome 17 near D17Mit133 contains a syntenic region to human chromosome 6q27, which was recently identified to be linked to lung function in humans. The identified intervals harbor valuable candidate genes, such as the relaxin1 and transforming growth factor beta receptor 3 gene, which revealed missense polymorphisms between the parental strains.

CONCLUSION

The study provides evidence for linkage of different measures of lung function on murine chromosomes 5, 15, 17, and 19 and suggests novel candidate genes that may also affect the expression of human pulmonary function.

Polymorphisms in the CD14 gene associated with pulmonary function in farmers

RATIONALE AND OBJECTIVES

Farmers experience airway obstruction, which may be attributable in part to endotoxin inhalation. CD14 is a receptor for endotoxin.

MATERIALS AND METHODS

Based on our findings of increased circulating CD14 associated with the CD14/-159 T allele, we hypothesized that carriers of this allele would have decreased lung function among endotoxin-exposed individuals. CD14/-159TT farmers (n = 19) had significantly lower lung function as measured by FEV1 (p = 0.028) and mean forced expiratory flow during the middle half of the FVC (FEF25-75) (p = 0.05) compared with farmers with the C allele (n = 78). Also, farmers with the CD14/-1619GG genotype (n =11) were associated with lower lung function (FEV1, p = 0.008; FEF25-75, p = 0.009) compared with farmers with the A allele (n = 86).

RESULTS

No association between CD14/-550 and lung function was observed (FEV1, p = 0.32; FEF25-75, p = 0.11). Increased prevalence of wheezing was reported in farmers homozygous for CD14/-159T (p = 0.013) or CD14/-1619G (p = 0.019) compared with farmers with the CC or AA genotype, respectively. No association was found between TLR4/Asp299Gly and lung function or wheeze.

CONCLUSION

We conclude that the CD14/-159 or CD14/-1619 loci may play a role in modulating lung function and wheeze among agricultural workers.

Genome-wide linkage of forced mid-expiratory flow in chronic obstructive pulmonary disease

Familial aggregation of forced expiratory flow during the middle half of the FVC (FEF(25-75%)) and FEF(25-75%)/FVC has been observed in the Boston Early-Onset Chronic Obstructive Pulmonary Disease Study, but linkage results have not been reported for these phenotypes. An autosomal whole genome-wide linkage scan was performed in 72 pedigrees ascertained through a proband with severe, early-onset chronic obstructive pulmonary disease, and linkage analyses of FEF(25-75%) and FEF(25-75%)/FVC were performed using Sequential Oligogenic Linkage Analysis Routines. There was suggestive evidence for linkage of FEF(25-75%)/FVC with chromosome 2 (LOD 2.60 at 216 cM). In a smokers-only analysis, evidence for linkage was observed for postbronchodilator FEF(25-75%) with chromosome 12 (LOD 5.03 at 35 cM) and chromosomes 2 and 12 for FEF(25-75%)/FVC (LOD 4.12 at 221 cM and LOD 3.46 at 35 cM, respectively); in the smokers-only model, evidence for linkage also was robust for FEV(1)/FVC on chromosome 2 (LOD 4.13 at 229 cM) and FEV(1) on chromosome 12 (LOD 3.26 at 36 cM). Our analyses provide evidence for linkage of FEF(25-75%) and FEF(25-75%)/FVC on chromosomes 2q and 12p. LOD scores of greater than two were also observed for chromosomes 16, 20, and 22 with the smokers-only analysis, which may suggest gene-by-smoking interactions in these regions.

Alpha1-antitrypsin deficiency. 2: genetic aspects of alpha(1)-antitrypsin deficiency: phenotypes and genetic modifiers of emphysema risk

The genetic aspects of AAT deficiency and the variable manifestations of lung disease in PI Z individuals are reviewed. The role of modifying genetic factors which may interact with environmental factors (such as cigarette smoking) is discussed, and directions for future research are presented.