Candidate Gene-based Association Studies Research Articles

Identification of superior haplotypes for flowering time in pigeonpea through candidate gene-based association study of a diverse minicore collection.

In current study candidate gene (261 genes) based association mapping on 144 pigeonpea accessions for flowering time and related traits and 29 MTAs producing eight superior haplotypes were identified. In the current study, we have conducted an association analysis for flowering-associated traits in a diverse pigeonpea mini-core collection comprising 144 accessions using the SNP data of 261 flowering-related genes. In total, 13,449 SNPs were detected in the current study, which ranged from 743 (ICP10228) to 1469 (ICP6668) among the individuals. The nucleotide diversity (0.28) and Watterson estimates (0.34) reflected substantial diversity, while Tajima's D (-0.70) indicated the abundance of rare alleles in the collection. A total of 29 marker trait associations (MTAs) were identified, among which 19 were unique to days to first flowering (DOF) and/or days to fifty percent flowering (DFF), 9 to plant height (PH), and 1 to determinate (Det) growth habit using 3years of phenotypic data. Among these MTAs, six were common to DOF and/or DFF, and four were common to DOF/DFF along with the PH, reflecting their pleiotropic action. These 29 MTAs spanned 25 genes, among which 10 genes clustered in the protein-protein network analysis, indicating their concerted involvement in floral induction. Furthermore, we identified eight haplotypes, four of which regulate late flowering, while the remaining four regulate early flowering using the MTAs. Interestingly, haplotypes conferring late flowering (H001, H002, and H008) were found to be taller, while those involved in early flowering (H003) were shorter in height. The expression pattern of these genes, as inferred from the transcriptome data, also underpinned their involvement in floral induction. The haplotypes identified will be highly useful to the pigeonpea breeding community for haplotype-based breeding.

Identification of TNF-α as Major Susceptible Risk Locus for Vitiligo: A Systematic Review and Meta-Analysis Study in the Asian Population

Introduction: Vitiligo is a common depigmentation disorder characterized by defined white patches on the skin and affecting around 0.5% to 2% of the general population. Genetic association studies have identified several pre-disposing genes and single nucleotide polymorphisms (SNPs) for vitiligo pathogenesis; nonetheless, the reports are often conflicting and rarely conclusive. This comprehensive meta-analysis study was designed to evaluate the effect of the risk variants on vitiligo aetiology and covariate stratified vitiligo risk in the Asian population, considering all the studies published so far. Methods: We followed a systematic and comprehensive search to identify the relevant vitiligo-related candidate gene association studies in PubMed using specific keywords. After data extraction, we calculated, for the variants involved, the study-level unadjusted odds ratio, standard errors, and 95% confidence intervals by using logistic regression with additive, dominant effect, and recessive models using R software package (R, 3.4.2) “metafor.” Subgroup analysis was performed using logistic regression (generalized linear model; “glm”) of disease status on subgroup-specific genotype counts. For a better understanding of the likely biological function of vitiligo-associated variant obtained through the meta-analysis, in silico functional analyses, through standard publicly available web tools, were also conducted. Results: Thirty-one vitiligo-associated case-control studies on eleven SNPs were analysed in our study. In the fixed-effect meta-analysis, one variant upstream of TNF-α gene: rs1800629 was found to be associated with vitiligo risk in the additive (p = 4.26E−06), dominant (p = 1.65E−7), and recessive (p = 0.000453) models. After Benjamini-Hochberg false discovery rate (FDR) correction, rs1800629/TNF-α was found to be significant at 5% FDR in the dominant (padj = 1.82E−6) and recessive models (padj = 0.0049). In silico characterization revealed the prioritized variant to be regulatory in nature and thus having potential to contribute towards vitiligo pathogenesis. Conclusion: Our study constitutes the first comprehensive meta-analysis of candidate gene-based association studies reported in the whole of the Asian population, followed by an in silico analysis of the vitiligo-associated variant. According to the findings of our study, TNF-α single nucleotide variant rs1800629G>A has a risk association, potentially contributing to vitiligo pathogenesis in the Asian population.

Current Data and New Insights into the Genetic Factors of Atherogenic Dyslipidemia Associated with Metabolic Syndrome.

Atherogenic dyslipidemia plays a critical role in the development of metabolic syndrome (MetS), being one of its major components, along with central obesity, insulin resistance, and hypertension. In recent years, the development of molecular genetics techniques and extended analysis at the genome or exome level has led to important progress in the identification of genetic factors (heritability) involved in lipid metabolism disorders associated with MetS. In this review, we have proposed to present the current knowledge related to the genetic etiology of atherogenic dyslipidemia, but also possible challenges for future studies. Data from the literature provided by candidate gene-based association studies or extended studies, such as genome-wide association studies (GWAS) and whole exome sequencing (WES,) have revealed that atherogenic dyslipidemia presents a marked genetic heterogeneity (monogenic or complex, multifactorial). Despite sustained efforts, many of the genetic factors still remain unidentified (missing heritability). In the future, the identification of new genes and the molecular mechanisms by which they intervene in lipid disorders will allow the development of innovative therapies that act on specific targets. In addition, the use of polygenic risk scores (PRS) or specific biomarkers to identify individuals at increased risk of atherogenic dyslipidemia and/or other components of MetS will allow effective preventive measures and personalized therapy.

The Genetic Architecture of the Etiology of Lower Extremity Peripheral Artery Disease: Current Knowledge and Future Challenges in the Era of Genomic Medicine.

Lower extremity artery disease (LEAD), caused by atherosclerotic obstruction of the arteries of the lower limb extremities, has exhibited an increase in mortality and morbidity worldwide. The phenotypic variability of LEAD is correlated with its complex, multifactorial etiology. In addition to traditional risk factors, it has been shown that the interaction between genetic factors (epistasis) or between genes and the environment potentially have an independent role in the development and progression of LEAD. In recent years, progress has been made in identifying genetic variants associated with LEAD, by Genome-Wide Association Studies (GWAS), Whole Exome Sequencing (WES) studies, and epigenetic profiling. The aim of this review is to present the current knowledge about the genetic factors involved in the etiopathogenic mechanisms of LEAD, as well as possible directions for future research. We analyzed data from the literature, starting with candidate gene-based association studies, and then continuing with extensive association studies, such as GWAS and WES. The results of these studies showed that the genetic architecture of LEAD is extremely heterogeneous. In the future, the identification of new genetic factors will allow for the development of targeted molecular therapies, and the use of polygenic risk scores (PRS) to identify individuals at an increased risk of LEAD will allow for early prophylactic measures and personalized therapy to improve their prognosis.

Genome-wide analysis of the serine carboxypeptidase-like (SCPL) proteins in Brassica napus L.

The serine carboxypeptidase-like protein (SCPL) family plays a key part in plant growth, development and stress responses. However, the serine carboxypeptidase-like (SCPL) proteins in Brassica napus L. (B. napus) have not been reported yet. Here, we identified a total of 117 putative SCPL genes in B. napus, which were unevenly distributed on all 19 chromosomes and were divided into three groups (carboxypeptidase Ⅰ to Ⅲ) according to their phylogenetic relationships. Synteny and duplication analysis revealed that the SCPL gene family of B. napus was amplified during allopolyploidization, in which the whole genome triplication and dispersed duplication played critical roles. After the separation of Brassica and Arabidopsis lineages, orthologous gene analysis showed that many SCPL genes were lost during the evolutionary process in B. rapa, B. oleracea and B. napus. Subsequently, the analyses of the gene structure, conserved motifs, cis-element and expression patterns showed that the members in the same group were highly conserved. Furthermore, candidate gene based association study suggested the role of BnSCPL52 in controlling seed number per silique, seed weight and silique length and a CAPS marker was developed to distinguish different haplotypes. Our results provide an overview of rapeseed SCPL genes that enable us for further functional research and benefit the marker-assisted breeding in Brassica napus.

Etiologic Puzzle of Coronary Artery Disease: How Important Is Genetic Component?

In the modern era, coronary artery disease (CAD) has become the most common form of heart disease and, due to the severity of its clinical manifestations and its acute complications, is a major cause of morbidity and mortality worldwide. The phenotypic variability of CAD is correlated with the complex etiology, multifactorial (caused by the interaction of genetic and environmental factors) but also monogenic. The purpose of this review is to present the genetic factors involved in the etiology of CAD and their relationship to the pathogenic mechanisms of the disease. Method: we analyzed data from the literature, starting with candidate gene-based association studies, then continuing with extensive association studies such as Genome-Wide Association Studies (GWAS) and Whole Exome Sequencing (WES). The results of these studies revealed that the number of genetic factors involved in CAD etiology is impressive. The identification of new genetic factors through GWASs offers new perspectives on understanding the complex pathophysiological mechanisms that determine CAD. In conclusion, deciphering the genetic architecture of CAD by extended genomic analysis (GWAS/WES) will establish new therapeutic targets and lead to the development of new treatments. The identification of individuals at high risk for CAD using polygenic risk scores (PRS) will allow early prophylactic measures and personalized therapy to improve their prognosis.

Genome‐wide analysis of genomic imprinting in the endosperm and allelic variation in flax

Genomic imprinting is an epigenetic phenomenon that causes biased expression of maternally and paternally inherited alleles. In flowering plants, genomic imprinting predominantly occurs in the triploid endosperm and plays a vital role in seed development. In this study, we identified 248 candidate imprinted genes including 114 maternally expressed imprinted genes (MEGs) and 134 paternally expressed imprinted genes(PEGs) in flax (Linum usitatissimum L.) endosperm using deep RNA sequencing. These imprinted genes were neither clustered in specific chromosomal regions nor well conserved among flax and other plant species. MEGs tended to be expressed specifically in the endosperm, whereas the expression of PEGs was not tissue-specific. Imprinted single nucleotide polymorphisms differentiated 200 flax cultivars into the oil flax, oil-fiber dual purpose flax and fiber flax subgroups, suggesting that genomic imprinting contributed to intraspecific variation in flax. The nucleotide diversity of imprinted genes in the oil flax subgroup was significantly higher than that in the fiber flax subgroup, indicating that some imprinted genes underwent positive selection during flax domestication from oil flax to fiber flax. Moreover, imprinted genes that underwent positive selection were related to flax functions. Thirteen imprinted genes related to flax seed size and weight were identified using a candidate gene-based association study. Therefore, our study provides information for further exploration of the function and genomic variation of imprinted genes in the flax population.

A candidate gene-based association study of introgressed pod shatter resistance in Brassica napus

Yield losses at maturity due to unsynchronized pod shattering remain a major rapeseed breeding challenge. Variation for shatter resistance in the germplasm collections is inadequate for breeding manipulations. We have recently transferred resistance to pod shattering from Brassica carinata to Brassica napus . Introgression lines (ILs) were phenotyped for shatter resistance using the pendulum machine. Introgressive breeding was successful in enhancing rupture energy in the ILs, which varied from 1.8 to 7.2 mJ for E1 and 2.7 to 6.5 mJ for E2 while the corresponding values for natural B. napus ranged from 2.2 - 3.5 mJ (E1) and 2.2 - 4.3 mJ (E2) respectively. B. carinata had an average rupture energy of 6.3 mJ (pooled over environments). On the basis of data averaged over two environments, I2 (6.3 mJ), I3 (5.2 mJ), I8 (5.6 mJ), I22 (5.1 mJ), I32 (5.2 mJ) and I41 (5.2 mJ) appeared very promising as germplasm resources for future breeding. Significant marker trait association between candidate gene NAC and rupture energy explained 19% of variation for the trait. NDEH 3 also appeared to be associated with rupture energy under E1. These polymorphisms represent promising candidates for the development of molecular markers for marker-assisted deployment of introgressed shatter resistance.

Annotation of susceptibility SNPs associated with atrial fibrillation.

Objective: Genome-wide association studies (GWAS) and the candidate gene based association studies have identified a panel of variants associated with atrial fibrillation (AF), however, most of the identified single nucleotide polymorphisms (SNPs) were found located within intergenic or intronic genomic regions, and whether the positive SNPs have a real biological function is unknown, and the real disease causing gene need to be studied.Results: The current results of the genetic studies including common variants identified by GWAS (338 index SNPs) and candidate gene based association studies (40 SNPs) were summarized.Conclusion: Our study suggests the relationship between genetic variants and possible targeted genes, and provides insight into potential genetic pathways underlying AF incidence and development. The results may provide an encyclopedia of AF susceptibility SNPs and shed light on the functional mechanisms of AF variants identified through genetic studies.Methods: We summarized AF susceptibility SNPs identified by GWAS and candidate gene based association studies, and give a comprehensive functional annotation of all these AF susceptibility loci. by genomic annotation, microRNA binding prediction, promoter activity analysis, enhancer activity analysis, transcription factors binding activity prediction, expression quantitative trait loci (eQTL) analysis, long-range transcriptional regulatory function analysis, gene ontology and pathway enrichment analysis.

The sucrose transporter MdSUT4.1 participates in the regulation of fruit sugar accumulation in apple

BackgroundSugar content is an important determinant of fruit sweetness, but details on the complex molecular mechanism underlying fruit sugar accumulation remain scarce. Here, we report the role of sucrose transporter (SUT) family in regulating fruit sugar accumulation in apple.ResultsGene-tagged markers were developed to conduct candidate gene-based association study, and an SUT4 member MdSUT4.1 was found to be significantly associated with fruit sugar accumulation. MdSUT4.1 encodes a tonoplast localized protein and its expression level had a negative correlation with fruit sugar content. Overexpression of MdSUT4.1 in strawberry and apple callus had an overall negative impact on sugar accumulation, suggesting that it functions to remobilize sugar out of the vacuole. In addition, MdSUT4.1 is located on chromosomal region harboring a previously reported QTL for sugar content, suggesting that it is a candidate gene for fruit sugar accumulation in apple.ConclusionsMdSUT4.1 is involved in the regulation of fruit sugar accumulation in apple. This study is not only helpful for understanding the complex mechanism of fruit sugar accumulation, but it also provides molecular tools for genetic improvement of fruit quality in breeding programs of apple.

Knockdown of SlNL33 accumulates ascorbate, enhances disease and oxidative stress tolerance in tomato (Solanum lycopersicum)

Ascorbic acid (AsA) is an antioxidant that plays an important role in scavenging reactive oxygen species and enhancing disease resistance in plants. In tomato, unlike biosynthesis pathway, the regulatory network of ascorbate remains largely unclear. Here, we reported the isolation and characterization of SlNL33, the gene that encodes an NL type NBS-LRR resistance protein by candidate gene-based association study. Knockdown of SlNL3 by RNA interference in tomato (Solanum lycopersicum cv. Ailsa Craig) increased AsA level in both fruit (~ 1.3 fold) and leaf (more than twofold). qRT–PCR analysis revealed that elevated expression of several structural genes involved in ascorbate biosynthesis including GMP4, GME1, GGP1, GalDH, GLDH, MIOX, MDHAR, and DHAR, may contribute to the ascorbate accumulation in SlNL33 RNAi lines compared with wild-type. Furthermore, the SlNL33-RNAi transgenic lines showed enhanced tolerance to oxidative stress by methyl viologen and gray mold infection by Botrytis cinerea respectively, as compared to control plants. Taken together, the present findings revealed that SlNL33 was the first identified NBS-LRR gene that plays a negative role in the AsA accumulation as well as biotic and abiotic stress tolerance in tomato.

Haplotype analysis of key genes governing grain yield and quality traits across 3K RG panel reveals scope for the development of tailor-made rice with enhanced genetic gains.

SummaryThough several genes governing various major traits have been reported in rice, their superior haplotype combinations for developing ideal variety remains elusive. In this study, haplotype analysis of 120 previously functionally characterized genes, influencing grain yield (87 genes) and grain quality (33 genes) revealed significant variations in the 3K rice genome (RG) panel. For selected genes, meta‐expression analysis using already available datasets along with co‐expression network provided insights at systems level. Also, we conducted candidate gene based association study for the 120 genes and identified 21 strongly associated genes governing 10‐grain yield and quality traits. We report superior haplotypes upon phenotyping the subset of 3K RG panel, SD1‐H8 with haplotype frequency (HF) of 30.13% in 3K RG panel, MOC1‐H9 (HF: 23.08%), IPA1‐H14 (HF: 6.64%), DEP3‐H2 (HF: 5.59%), DEP1‐H2 (HF: 37.53%), SP1‐H3 (HF: 5.05%), LAX1‐H5 (HF: 1.56%), LP‐H13 (3.64%), OSH1‐H4 (5.52%), PHD1‐H14 (HF: 15.21%), AGO7‐H15 (HF: 3.33%), ROC5‐H2 (31.42%), RSR1‐H8 (HF: 4.20%) and OsNAS3‐H2 (HF: 1.00%). For heading date, Ghd7‐H8 (HF: 3.08%), TOB1‐H10 (HF: 4.60%) flowered early, Ghd7‐H14 (HF: 42.60%), TRX1‐H9 (HF: 27.97%), OsVIL3‐H14 (HF: 1.72%) for medium duration flowering, while Ghd7‐H6 (HF: 1.65%), SNB‐H9 (HF: 9.35%) were late flowering. GS5‐H4 (HF: 65.84%) attributed slender, GS5‐H5 (HF: 29.00%), GW2‐H2 (HF: 4.13%) were medium slender and GS5‐H9 (HF: 2.15%) for bold grains. Furthermore, haplotype analysis explained possible genetic basis for superiority of selected mega‐varieties. Overall, this study suggests the possibility for developing next‐generation tailor‐made rice with superior haplotype combinations of target genes suiting future food and nutritional demands via haplotype‐based breeding.

Sunflower Hybrid Breeding: From Markers to Genomic Selection.

In sunflower, molecular markers for simple traits as, e.g., fertility restoration, high oleic acid content, herbicide tolerance or resistances to Plasmopara halstedii, Puccinia helianthi, or Orobanche cumana have been successfully used in marker-assisted breeding programs for years. However, agronomically important complex quantitative traits like yield, heterosis, drought tolerance, oil content or selection for disease resistance, e.g., against Sclerotinia sclerotiorum have been challenging and will require genome-wide approaches. Plant genetic resources for sunflower are being collected and conserved worldwide that represent valuable resources to study complex traits. Sunflower association panels provide the basis for genome-wide association studies, overcoming disadvantages of biparental populations. Advances in technologies and the availability of the sunflower genome sequence made novel approaches on the whole genome level possible. Genotype-by-sequencing, and whole genome sequencing based on next generation sequencing technologies facilitated the production of large amounts of SNP markers for high density maps as well as SNP arrays and allowed genome-wide association studies and genomic selection in sunflower. Genome wide or candidate gene based association studies have been performed for traits like branching, flowering time, resistance to Sclerotinia head and stalk rot. First steps in genomic selection with regard to hybrid performance and hybrid oil content have shown that genomic selection can successfully address complex quantitative traits in sunflower and will help to speed up sunflower breeding programs in the future. To make sunflower more competitive toward other oil crops higher levels of resistance against pathogens and better yield performance are required. In addition, optimizing plant architecture toward a more complex growth type for higher plant densities has the potential to considerably increase yields per hectare. Integrative approaches combining omic technologies (genomics, transcriptomics, proteomics, metabolomics and phenomics) using bioinformatic tools will facilitate the identification of target genes and markers for complex traits and will give a better insight into the mechanisms behind the traits.

Neuroblastoma survivors are at increased risk for second malignancies: A report from the International Neuroblastoma Risk Group Project

BackgroundThe incidence of second malignant neoplasm (SMN) within the first ten years of diagnosis in high-risk neuroblastoma patients treated with modern, intensive therapy is unknown. Further, the underlying germline genetics that contribute to SMN in these survivors are not known. MethodsThe International Neuroblastoma Risk Group (INRG) database of patients diagnosed from 1990 to 2010 was analysed. SMN risk was accessed by cumulative incidence, standardised incidence ratios (SIRs) and absolute excess risk. A candidate gene-based association study evaluated genetic susceptibility to SMN in neuroblastoma survivors. ResultsOf the 5987 patients in the INRG database with SMN data enrolled in a clinical trial, 43 (0.72%) developed a SMN. The 10-year cumulative incidence of SMN for high-risk patients was 1.8% (95% confidence interval [CI] 1.0–2.6%) compared with 0.38% (95% CI: 0.22–0.94%) for low-risk patients (P = 0.01). High-risk patients had an almost 18-fold higher incidence of SMN compared to age- and sex-matched controls (SIR = 17.5 (95% CI: 11.4–25.3), absolute excess risk = 27.6). For patients treated on high- and intermediate-risk clinical trials, the SIR of acute myelogenous leukaemia was 106.8 (95% CI: 28.7–273.4) and 127.7 (95%CI: 25.7–373.3), respectively. Variants implicating DNA repair genes XRCC3 (rs861539: P = 0.006; odds ratio: 2.04, 95%CI: 1.19–3.46) and MSH2 (rs17036651: P = 0.009; odds ratio: 0.26, 95% CI: 0.08–0.81) were associated with SMN. ConclusionThe intensive multi-modality treatment strategy currently used to treat high-risk neuroblastoma is associated with a significantly increased risk of secondary acute myelogenous leukaemia. Defining the interactions of treatment exposures and genetic factors that promote the development of SMN is critical for optimising survivorship care.

Crucial roles of the CHRNB3-CHRNA6 gene cluster on chromosome 8 in nicotine dependence: update and subjects for future research.

Cigarette smoking is a leading cause of preventable death throughout the world. Nicotine, the primary addictive compound in tobacco, plays a vital role in the initiation and maintenance of its use. Nicotine exerts its pharmacological roles through nicotinic acetylcholine receptors (nAChRs), which are ligand-gated ion channels consisting of five membrane-spanning subunits. Besides the CHRNA4, CHRNB2 and CHRNA5/A3/B4 cluster on chromosome 15, which has been investigated intensively, recent evidence from both genome-wide association studies and candidate gene-based association studies has revealed the crucial roles of the CHRNB3–CHRNA6 gene cluster on chromosome 8 in nicotine dependence (ND). These studies demonstrate two distinct loci within this region. The first one is tagged by rs13277254, upstream of the CHRNB3 gene, and the other is tagged by rs4952, a coding single nucleotide polymorphism in exon 5 of that gene. Functional studies by genetic manipulation in mice have shown that α6*-nAChRs, located in the ventral tegmental area (VTA), are of great importance in controlling nicotine self-administration. However, when the α6 subunit is selectively re-expressed in the VTA of the α6−/− mouse by a lentiviral vector, the reinforcing property of nicotine is restored. To further determine the role of α6*-nAChRs in the process of nicotine-induced reward and withdrawal, genetic knock-in strains have been examined, which showed that replacement of Leu with Ser in the 9′ residue in the M2 domain of α6 produces nicotine-hypersensitive mice (α6 L9′S) with enhanced dopamine release. Moreover, nicotine-induced upregulation may be another ingredient in the pathology of nicotine addiction although the effect of chronic nicotine exposure on the expression of α6-containing receptors is controversial. To gain a better understanding of the pathological processes underlying ND and ND-related behaviors and to promote the development of effective smoking cessation therapies, we here present the most recent studies concerning the genetic effects of the CHRNB3–CHRNA6 gene cluster in ND.

Using a Candidate Gene-Based Genetic Linkage Map to Identify QTL for Winter Survival in Perennial Ryegrass.

Important agronomical traits in perennial ryegrass (Lolium perenne) breeding programs such as winter survival and heading date, are quantitative traits that are generally controlled by multiple loci. Individually, these loci have relatively small effects. The aim of this study was to develop a candidate gene based Illumina GoldenGate 1,536-plex assay, containing single nucleotide polymorphism markers designed from transcripts involved in response to cold acclimation, vernalization, and induction of flowering. The assay was used to genotype a mapping population that we have also phenotyped for winter survival to complement the heading date trait previously mapped in this population. A positive correlation was observed between strong vernalization requirement and winter survival, and some QTL for winter survival and heading date overlapped on the genetic map. Candidate genes were located in clusters along the genetic map, some of which co-localized with QTL for winter survival and heading date. These clusters of candidate genes may be used in candidate gene based association studies to identify alleles associated with winter survival and heading date.

A candidate gene-based association study reveals SNPs significantly associated with bud burst in European beech (Fagus sylvatica L.)

European beech (Fagus sylvatica L.) is one of the most important deciduous forest tree species in Central Europe. Nevertheless, its adaptation potential to climate change is controversially discussed, and little is known about the molecular basis of climate change-relevant traits like bud burst. Here, we directly observed bud burst of beech seedlings originating from six different populations in Northern Germany in a large translocation experiment comprising 3600 individuals in three consecutive years. We genotyped more than 1200 individuals from the translocation experiment using 46 different SNP markers previously identified in candidate genes for bud burst. Association and outlier analyses were conducted to identify potentially adaptive SNPs. We found 10 SNPs significantly associated with bud burst in at least one analyzed year and five outlier SNPs potentially under directional selection. One SNP located in a histone gene was simultaneously revealed by both association and outlier analyses. This SNP might have the highest probability of being involved in the expression of bud burst.

Exome Analyses of Long QT Syndrome Reveal Candidate Pathogenic Mutations in Calmodulin-Interacting Genes.

Long QT syndrome (LQTS) is an arrhythmogenic disorder that can lead to sudden death. To date, mutations in 15 LQTS-susceptibility genes have been implicated. However, the genetic cause for approximately 20% of LQTS patients remains elusive. Here, we performed whole-exome sequencing analyses on 59 LQTS and 61 unaffected individuals in 35 families and 138 unrelated LQTS cases, after genetic screening of known LQTS genes. Our systematic analysis of familial cases and subsequent verification by Sanger sequencing identified 92 candidate mutations in 88 genes for 23 of the 35 families (65.7%): these included eleven de novo, five recessive (two homozygous and three compound heterozygous) and seventy-three dominant mutations. Although no novel commonly mutated gene was identified other than known LQTS genes, protein-protein interaction (PPI) network analyses revealed ten new pathogenic candidates that directly or indirectly interact with proteins encoded by known LQTS genes. Furthermore, candidate gene based association studies using an independent set of 138 unrelated LQTS cases and 587 controls identified an additional novel candidate. Together, mutations in these new candidates and known genes explained 37.1% of the LQTS families (13 in 35). Moreover, half of the newly identified candidates directly interact with calmodulin (5 in 11; comparison with all genes; p=0.042). Subsequent variant analysis in the independent set of 138 cases identified 16 variants in the 11 genes, of which 14 were in calmodulin-interacting genes (87.5%). These results suggest an important role of calmodulin and its interacting proteins in the pathogenesis of LQTS.

Strong Impact of TGF-β1 Gene Polymorphisms on Breast Cancer Risk in Indian Women: A Case-Control and Population-Based Study

IntroductionTGF-β1 is a multi-functional cytokine that plays an important role in breast carcinogenesis. Critical role of TGF-β1 signaling in breast cancer progression is well documented. Some TGF-β1 polymorphisms influence its expression; however, their impact on breast cancer risk is not clear.MethodsWe analyzed 1222 samples in a candidate gene-based genetic association study on two distantly located and ethnically divergent case-control groups of Indian women, followed by a population-based genetic epidemiology study analyzing these polymorphisms in other Indian populations. The c.29C>T (Pro10Leu, rs1982073 or rs1800470) and c.74G>C (Arg25Pro, rs1800471) polymorphisms in the TGF-β1 gene were analyzed using direct DNA sequencing, and peripheral level of TGF-β1 were measured by ELISA.Resultsc.29C>T substitution increased breast cancer risk, irrespective of ethnicity and menopausal status. On the other hand, c.74G>C substitution reduced breast cancer risk significantly in the north Indian group (p = 0.0005) and only in the pre-menopausal women. The protective effect of c.74G>C polymorphism may be ethnicity-specific, as no association was seen in south Indian group. The polymorphic status of c.29C>T was comparable among Indo-Europeans, Dravidians, and Tibeto-Burmans. Interestingly, we found that Tibeto-Burmans lack polymorphism at c.74G>C locus as true for the Chinese populations. However, the Brahmins of Nepal (Indo-Europeans) showed polymorphism in 2.08% of alleles. Mean TGF-β1 was significantly elevated in patients in comparison to controls (p<0.001).Conclusionc.29C>T and c.74G>C polymorphisms in the TGF-β1 gene significantly affect breast cancer risk, which correlates with elevated TGF-β1 level in the patients. The c.29C>T locus is polymorphic across ethnically different populations, but c.74G>C locus is monomorphic in Tibeto-Burmans and polymorphic in other Indian populations.

An association study of TOLL and CARD with leprosy susceptibility in Chinese population

Previous genome-wide association studies (GWASs) identified multiple susceptibility loci that have highlighted the important role of TLR (Toll-like receptor) and CARD (caspase recruitment domain) genes in leprosy. A large three-stage candidate gene-based association study of 30 TLR and 47 CARD genes was performed in the leprosy samples of Chinese Han. Of 4363 SNPs investigated, eight SNPs showed suggestive association (P < 0.01) in our previously published GWAS datasets (Stage 1). Of the eight SNPs, rs2735591 and rs4889841 showed significant association (P < 0.001) in an independent series of 1504 cases and 1502 controls (Stage 2), but only rs2735591 (next to BCL10) showed significant association in the second independent series of 938 cases and 5827 controls (Stage 3). Rs2735591 showed consistent association across the three stages (P > 0.05 for heterogeneity test), significant association in the combined validation samples (Pcorrected = 5.54 × 10−4 after correction for 4363 SNPs tested) and genome-wide significance in the whole GWAS and validation samples (P = 1.03 × 10−9, OR = 1.24). In addition, we demonstrated the lower expression of BCL10 in leprosy lesions than normal skins and a significant gene connection between BCL10 and the eight previously identified leprosy loci that are associated with NFκB, a major regulator of downstream inflammatory responses, which provides further biological evidence for the association. We have discovered a novel susceptibility locus on 1p22, which implicates BCL10 as a new susceptibility gene for leprosy. Our finding highlights the important role of both innate and adaptive immune responses in leprosy.