Genetic Association Analyses of Nitric Oxide Synthase Genes and Neural Tube Defects Vary by Phenotype

Neural tube defects (NTDs) are caused by improper neural tube closure during the early stages of embryonic development. NTDs are hypothesized to have a complex genetic origin and numerous candidate genes have been proposed. The nitric oxide synthase 3 (NOS3) G594T polymorphism has been implicated in risk for spina bifida, and interactions between that single nucleotide polymorphism (SNP) and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism have also been observed. To evaluate other genetic variation in the NO pathway in the development of NTDs, we examined all three NOS genes: NOS1, NOS2, and NOS3. Using 3109 Caucasian samples in 745 families, we evaluated association in the overall dataset and within specific phenotypic subsets. Haplotype tagging SNPs in the NOS genes were tested for genetic association with NTD subtypes, both for main effects as well as for the presence of interactions with the MTHFR C677T polymorphism. Nominal main effect associations were found with all subtypes, across all three NOS genes, and interactions were observed between SNPs in all three NOS genes and MTHFR C677T. Unlike the previous report, the most significant associations in our dataset were with cranial subtypes and the AG genotype of rs4795067 in NOS2 (p = 0.0014) and the interaction between the rs9658490 G allele in NOS1 and MTHFR 677TT genotype (p = 0.0014). Our data extend the previous findings by implicating a role for all three NOS genes, independently and through interactions with MTHFR, in risk not only for spina bifida, but all NTD subtypes.     

Fibroblast growth factor 20 polymorphisms and haplotypes strongly influence risk of Parkinson disease

The pathogenic process responsible for the loss of dopaminergic neurons within the substantia nigra of patients with Parkinson disease (PD) is poorly understood. Current research supports the involvement of fibroblast growth factor (FGF20) in the survival of dopaminergic cells. FGF20 is a neurotrophic factor that is preferentially expressed within the substantia nigra of rat brain. The human homologue has been mapped to 8p21.3-8p22, which is within an area of PD linkage revealed through our published genomic screen. To test whether FGF20 influences risk of PD, we genotyped five single-nucleotide polymorphisms (SNPs) lying within the FGF20 gene, in a large family study. We analyzed our sample (644 families) through use of the pedigree disequilibrium test (PDT), the genotype PDT, the multilocus-genotype PDT, and the family-based association test to assess association between risk of PD and alleles, genotypes, multilocus genotypes, and haplotypes. We discovered a highly significant association of PD with one intronic SNP, rs1989754 (P=.0006), and two SNPs, rs1721100 (P=.02) and ss20399075 (P=.0008), located in the 3' regulatory region in our overall sample. Furthermore, we detected a haplotype (A-G-C-C-T) that is positively associated with risk of PD (P=.0003), whereas a second haplotype (A-G-G-G-C) was found to be negatively associated with risk of PD (P=.0009). Our results strongly support FGF20 as a risk factor for PD.     

Comprehensive genetic evaluation of common E-cadherin sequence variants and prostate cancer risk: strong confirmation of functional promoter SNP

The E-cadherin gene (CDH1) has been proposed as a prostate cancer (PC) susceptibility gene in several studies. Aberrant protein expression has been related to prognosis and progression in PC. In addition, a functional promoter SNP (rs16260) has been found to associate with PC risk. We performed a comprehensive genetic analysis of CDH1 by using the method of haplotype tagged SNPs in a large Swedish population-based case-control study consisting of 801 controls and 1,636 cases. In addition, Swedish PC families comprising a total of 157 cases sampled for DNA were analyzed for selected SNPs. Seven SNPs, including the promoter SNP rs16260, that captured over 96% of CDH1 haplotype variation were selected as haplotype tagging SNPs and analyzed for associated PC risk. We observed significant confirmation of rs16260 (P=0.003) for cases with a positive family history of PC (FH+) both in an independent case-control population and in PC families. In addition, a common haplotype (HapB, 25%) including the variant allele of rs16260 was associated (P=0.004) with PC risk among FH+ cases. The promoter SNP rs16260 as well as HapB were significantly transmitted to affected offspring in PC families. We report strong confirmation of the association between PC risk in FH+ cases and a functional CDH1 promoter SNP in an independent population. In conjunction with the biological importance of CDH1 our findings encourage further evaluation of genetic variation in CDH1 in relation to PC etiology. Due to the difficulties in replication of genetic association studies, this finding is unusual and novel.     

CTLA4 and generalized vitiligo: two genetic association studies and a meta‐analysis of published data

Several lines of evidence have implicated the gene encoding cytotoxic T lymphocyte antigen 4 (CTLA4) in susceptibility to various autoimmune diseases. However, published studies of genetic association between CTLA4 polymorphisms and vitiligo have yielded conflicting results. Here, we describe two new genetic association studies of CTLA4 single‐nucleotide polymorphisms (SNPs) and generalized vitiligo in two independent Romanian Caucasian (CEU) case‐control cohorts. The first study, of SNPs rs1863800, rs231806, rs231775, rs3087243, rs11571302, rs11571297, and rs10932037, showed no allelic, genotypic, or haplotypic association with generalized vitiligo. The second study, of SNP rs231775, likewise showed no significant association. To enhance statistical power over that of any individual study, we carried out a meta‐analysis that incorporated these two new studies and all other published genetic association studies of CTLA4 SNPs and vitiligo in CEU populations. While there was no association with vitiligo overall, the meta‐analysis showed significant association of SNP rs231775 in that subgroup of vitiligo patients who also had other concomitant autoimmune diseases. Similarly, there was near‐significant association in this same patient subgroup with several other CTLA4 SNPs that are in linkage disequilibrium with rs231775. Our results indicate that the association of CTLA4 with vitiligo is weak, and indeed may be secondary, driven by primary genetic association of CTLA4 with other autoimmune diseases that are epidemiologically associated with vitiligo.     

Association between maternal COMT gene polymorphisms and fetal neural tube defects risk in a Chinese population

Maternal tea consumption was reported to increase the risk of fetal neural tube defects (NTDs). Catechol‐O‐methyltransferase (COMT) may be involved in the metabolism of polyphenolic methylation of tea, thus influence the risk of fetal NTDs. Methods: A total of 576 fetuses or newborns with NTDs and 594 healthy newborns were included in the case–control study. Information on maternal tea consumption, sociodemographic characteristics, reproductive history, and related behavior was collected through face‐to‐face interviews. Maternal blood samples were collected to examine polymorphisms in COMT, and the possible interaction of COMT and tea consumption was analyzed. RESULTS: After controlling for potential confounders, homozygotes of rs737865 showed an elevated risk for total NTDs (odds ratio [OR] = 2.04, 95% confidence interval [CI], 1.24–3.35) and for the anencephaly subtype (OR = 1.99, 95% CI, 1.17–3.39). The CC genotype of rs4633 was positively associated with the overall risk of NTDs (OR = 3.66, 95% CI, 1.05–12.83). Heterozygotes for rs4680 were associated with a decreased risk of spina bifida (OR = 0.71, 95% CI, 0.51–0.98). The COMT rs4680 A allele was negatively related with the risk of spina bifida, with adjusted OR = 0.64 (95% CI, 0.45–0.89). An interaction between tea consumption (1 to 2 cups/day) and the rs4680AA/AG genotype was found in the spina bifida subtype (P_interaction = .08). Conclusion: Several COMT variants were associated with elevated risk of NTDs in a Chinese population. Maternal tea consumption may be associated with an increased risk for fetal NTDs in genetically susceptible subgroups. Birth Defects Research (Part A) 100:22–29, 2014. © 2013 Wiley Periodicals, Inc.     

Polymorphisms in the AKT1 and AKT2 genes and oesophageal squamous cell carcinoma risk in an Eastern Chinese population

Ethnic Han Chinese are at high risk of developing oesophageal squamous cell carcinoma (ESCC). Aberrant activation of the AKT signalling pathway is involved in many cancers, including ESCC. Some single nucleotide polymorphisms (SNPs) in genes involved in this pathway may contribute to ESCC susceptibility. We selected five potentially functional SNPs in AKT1 (rs2494750, rs2494752 and rs10138277) and AKT2 (rs7254617 and rs2304186) genes and investigated their associations with ESCC risk in 1117 ESCC cases and 1096 controls in an Eastern Chinese population. None of individual SNPs exhibited an association with ESCC risk. However, the combined analysis of three AKT1 SNPs suggested that individuals carrying one of AKT1 variant genotypes had a decreased ESCC risk [adjusted odds ratio (OR) = 0.60, 95% CI = 0.42–0.87]. Further stratified analysis found that AKT1 rs2294750 SNP was associated with significantly decreased ESCC risk among women (adjusted OR = 0.63, 95% CI = 0.43–0.94) and non‐drinkers (OR = 0.79, 95% CI = 0.64–0.99). Similar protective effects on women (adjusted OR = 0.56, 95% CI = 0.37–0.83) and non‐drinker (adjusted OR = 0.75, 95% CI = 0.60–0.94) were also observed for the combined genotypes of AKT1 SNPs. Consistently, logistic regression analysis indicated significant gene–gene interactions among three AKT1 SNPs (P < 0.015). A three‐AKT1 SNP haplotype (C‐A‐C) showed a significant association with a decreased ESCC risk (adjusted OR = 0.70, 95% CI = 0.52–0.94). Multifactor dimensionality reduction analysis confirmed a high‐order gene–environment interaction in ESCC risk. Overall, we found that three AKT1 SNPs might confer protection against ESCC risk; nevertheless, these effects may be dependent on other risk factors. Our results provided evidence of important gene–environment interplay in ESCC carcinogenesis.     

Association analyses of CYP19 gene polymorphisms with height variation in a large sample of Caucasian nuclear families

Human height is a complex trait regulated by multiple genetic and environmental factors. CYP19 (cytochrome P450 19) encodes aromatase, which catalyses the rate-limiting step in the conversion of androgens to estrogens. Deleterious mutations in CYP19 can result in estrogen deficiency that will influence adult height to certain extent. In the present study, we aimed to test the associations between the CYP19 gene polymorphisms with adult height variation, using family-based association methods, such as QTDT (quantitative transmission disequilibrium test) and FBAT (family-based association test) in 1,873 subjects from 405 Caucasian nuclear families. We found one SNP (rs730154) significantly associated with height by both QTDT (P=0.0030) and FBAT (P=0.0016) analyses. Haplotype analyses corroborated our single-marker results by showing that the haplotypes in block 4 containing rs730154 were significantly associated with height variation. We thus concluded that CYP19 could be one of the genetic factors influencing adult height in Caucasians. Further studies are required to identify the causal functional variants responsible for Caucasian height within the CYP19 gene.Tie-Lin Yang and Dong-Hai Xiong have contributed equally to this work.     

No association of XRCC1 polymorphisms Arg194Trp and Arg399Gln with colorectal cancer risk

Background: X-ray repair cross complementation group 1 (XRCC1) plays a key role in base excision repair. The purpose of this study was to examine the association of two genetic polymorphisms in XRCC1 (rs1799782 and rs25487) with risk of colorectal polyps and colorectal cancer (CRC). Methods: In the ongoing colorectal cancer study of Austria (CORSA), a total of 3091 Caucasian participants was genotyped using 5′-nuclease TaqMan assays. Multiple logistic regression was applied to compare individuals of the control group against three different case groups namely CRC cases, high-risk and low-risk polyps. Results: The two investigated SNPs in XRCC1 were not found to be associated with neither CRC risk nor polyp risk. Comparing the CRC cases versus the controls the OR was 0.60 (95%CI 0.27–1.31) for the heterozygous polymorphic genotype of SNP rs1799782 and 1.47 (95%CI 0.81–2.65) for the homozygous polymorphic genotype of SNP rs25487. Comparing the high-risk polyp group versus the controls the OR was 2.64 (95%CI 0.61–11.42) for the homozygous polymorphic genotype of SNP rs1799782 and 0.89 (95%CI 0.60–1.33) for SNP rs25487, respectively. In an haplotype analysis also no statistically significant association was found. Conclusion: Our finding that none of the two investigated SNPs of XRCC1 were significantly associated with risk of CRC or polyps is consistent with the results of a recently published meta-analysis.     

Maternal PCMT1 gene polymorphisms and the risk of neural tube defects in a Chinese population of Lvliang high-risk area

Protein-L-isoaspartate (D-aspartate) O-methyltransferase 1 (PCMT1) gene encodes for the protein repair enzyme L-isoaspartate (D-aspartate) O-methyltransferase (PIMT), which is known to protect certain neural cells from Bax-induced apoptosis. Previous study has shown that PCMT1 polymorphisms rs4552 and rs4816 of infant are associated with spina bifida in the Californian population. The association between maternal polymorphism and neural tube defects is still uncovered. A case-control study was conducted to investigate a possible association between maternal PCMT1 and NTDs in Lvliang high-risk area of Shanxi Province in China, using a high-resolution DNA melting analysis genotyping method. We found that increased risk for anencephaly in isolated NTDs compared with the normal control group was observed for the G (vs. A) allele (p=0.034, OR=1.896, 95% CI, 1.04-3.45) and genotypes GG+GA (p=0.025, OR=2.237, 95% CI, 1.09-4.57). Although the significance was lost after multiple comparison correction, the results implied that maternal polymorphisms in PCMT1 might be a potential genetic risk factor for isolated anencephaly in this Chinese population.     

Genetic variants in telomere-maintaining genes and skin cancer risk

Telomere-related genes play an important role in maintaining the integrity of the telomeric structure that protects chromosome ends, and telomere dysfunction may lead to tumorigenesis. We evaluated the associations between 39 SNPs, including 38 tag-SNPs in telomere-related genes (TERT, TRF1, TRF2, TNKS2, and POT1) and one SNP (rs401681) in the TERT-CLPTM1L locus which has been identified as a susceptibility locus to skin cancer in the previous GWAS, and the risk of skin cancer in a case–control study of Caucasians nested within the Nurses’ Health Study (NHS) among 218 melanoma cases, 285 squamous cell carcinoma (SCC) cases, 300 basal cell carcinoma (BCC) cases, and 870 controls. Of the 39 SNPs evaluated, ten showed a nominal significant association with the risk of at least one type of skin cancer. After correction for multiple testing within each gene, two SNPs in the TERT gene (rs2853676 and rs2242652) and one SNP in the TRF1 gene (rs2981096) showed significant associations with the risk of melanoma. Also, the SNP rs401681 in the TERT-CLPTM1L locus was replicated for the association with melanoma risk. The additive odds ratio (OR) [95% confidence interval (95% CI)] of these four SNPs (rs2853676[T], rs2242652[A], rs2981096[G], and rs401681[C]) for the risk of melanoma was 1.43 (1.14–1.81), 1.50 (1.14–1.98), 1.87 (1.19–2.91), and 0.73 (0.59–0.91), respectively. Moreover, we found that the rs401681[C] was associated with shorter relative telomere length (P for trend, 0.05). We did not observe significant associations for SCC or BCC risk. Our study provides evidence for the contribution of genetic variants in the telomere-maintaining genes to melanoma susceptibility.     

Common variation in KLKB1 and essential hypertension risk: tagging-SNP haplotype analysis in a case-control study

The human plasma kallikrein gene (KLKB1) encodes plasma kallikrein, a serine protease that catalyzes the release of kinins and other vasoactive peptides and may be involved in the pathogenesis of hypertension. In this study, we performed a haplotype-based study to assess the effect of common genetic variation in the KLKB1 gene on the risk of essential hypertension. Eight common single nucleotide polymorphisms (SNPs) were selected from the HapMap database and used to determine the pattern of linkage disequilibrium (LD) and haplotype structure within the KLKB1 gene. Four tag SNPs were then identified with over 85% power to predict both common haplotypes and remaining common SNPs, and genotyped in 1,317 cases with essential hypertension and 1,269 healthy controls. Single SNP analyses indicated that SNPs rs2304595 and rs4253325 were significantly associated with hypertension, adjusted for covariates. Compared with the most common Hap2 CAGC, Hap1 AGAC and Hap3 CGAC, which carry the susceptible rs2304595 G allele and rs4253325 A allele, were found to significantly increase the risk of essential hypertension with adjusted odds ratios equal to 1.37 and 1.17, respectively (P < 0.0001 and 0.028). A strongly significant interaction with gene-drinking was also observed. Among drinkers, the adjusted OR for Hap1 relative to Hap2 was increased to 2.50 (95% CI, 2.40 to 2.61; P < 0.0001). This was the first study to perform association analysis of the KLKB1 gene with essential hypertension. Our findings suggested that common genetic variation in the KLKB1 gene might contribute to the risk of hypertension in the northern Han Chinese population. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Conflict of interests: None.     

Linkage disequilibrium pattern and age-at-diagnosis are critical for replicating genetic associations across ethnic groups in leprosy

One of the persistent challenges of genetic association studies is the replication of genetic marker-disease associations across ethnic groups. Here, we conducted high-density association mapping of PARK2/PACRG SNPs with leprosy and identified 69 SNPs significantly associated with leprosy in 198 single-case Vietnamese leprosy families. A total of 56 associated SNPs localized to the overlapping promoter regions of PARK2/PACRG. For this region, multivariate analysis identified four SNPs belonging to two major SNP bins (rs1333955, rs7744433) and two single SNP bins (rs2023004, rs6936895) that capture the combined statistical evidence (P = 1.1 × 10^?5) for association among Vietnamese patients. Next, we enrolled a case–control sample of 364 leprosy cases and 370 controls from Northern India. We genotyped all subjects for 149 SNPs that capture >80 % of the genetic variation in the Vietnamese sample and found 24 SNPs significantly associated with leprosy. Multivariate analysis identified three SNPs (rs1333955, rs9356058 and rs2023004) that capture the association with leprosy (P < 10^?8). Hence, two SNPs (rs1333955 and rs2023004) were replicated by multivariate analysis between both ethnic groups. Marked differences in the linkage disequilibrium pattern explained some of the differences in univariate analysis between the two ethnic groups. In addition, the strength of association for two promoter region SNP bins was significantly stronger among young leprosy patients in the Vietnamese sample. The same trend was observed in the Indian sample, but due to the higher age-at-diagnosis of the patients the age effect was less pronounced.     

Effects of genetic variants of ST8SIA2 and NCAM1 genes on seasonal mood changes and circadian preference in the general population

ST8SIA2 and NCAM1 are functionally related genes forming polysialic acid (PSA) - neural cell adhesion molecule (NCAM) complex in suprachiasmatic nucleus (SCN), the regulating site of circadian biological rhythm. In this study, the relationship of ST8SIA2 and NCAM1 with circadian and seasonal rhythms of human behavior was explored. Subjects were 261 healthy Korean adults who were free of any history of clinically significant psychiatric symptoms. The phenotypes were circadian preference and seasonal change of mood and behavior (seasonality) measured by the Composite Scale of Morningness and the Seasonal Pattern Assessment Questionnaire, respectively. Thirty-four single nucleotide polymorphisms (SNPs) across the ST8SIA2 region and 15 SNPs of NCAM1 were analyzed. A nominally significant association with seasonality and circadian preference was observed in 21 variants of both genes. After corrections for multiple testing, associations of 8 SNPs of ST8SIA2 and 2 SNPs of NCAM1 with seasonality remained significant. Some of these SNPs were also associated with psychiatric disorders in previous studies. This study demonstrated a meaningful and/or suggestive evidence of association between behavioral phenotypes reflecting human biological rhythm and two interplaying genes involved in the plasticity of SCN’s neuronal network.     

The maternal folate hydrolase gene polymorphism is associated with neural tube defects in a high-risk Chinese population

Folate hydrolase 1 (FOLH1) gene encodes intestinal folate hydrolase, which regulates intestinal absorption of dietary folate. Previous studies on the association between polymorphisms rs202676 and rs61886492 and the risk of neural tube defects (NTDs) were inconclusive. A case–control study of women with NTD-affected pregnancies (n = 160) and controls (n = 320) was conducted in the Chinese population of Lvliang, a high-risk area for NTDs. We genotyped the polymorphic sites rs202676 and rs61886492 and assessed maternal plasma folate and total homocysteine (tHcy). Our results showed that in case group, plasma folate concentrations were 18 % lower compared with those of control group (8.32 vs. 6.79 nmol/L, p = 0.033) and tHcy concentrations were 17 % higher (10.47 vs. 12.65 μmol/L, p = 0.047). Almost all samples had the rs61886492 GG genotype (99.78 %). The result showed that the frequency of GG genotype in rs202676 was significantly higher in group with multiple NTDs than in controls (p = 0.030, OR = 2.157, 95 % CI, 1.06–4.38). The multiple-NTD group showed higher maternal plasma concentrations of tHcy (10.47 vs. 13.96 μmol/L, p = 0.024). The GG genotype of rs202676 had a lower maternal folate and higher tHcy concentrations than other genotypes with no significant differences. The result of structural prediction indicated that this variation might change the spatial structure of the protein. These results suggested that the maternal polymorphism rs202676 was a potential risk factor for multiple NTDs in this Chinese population. The allele G might affect maternal plasma folate and tHcy concentration.     

Polymorphic variants in tenascin-C (TNC) are associated with atherosclerosis and coronary artery disease

Tenascin-C (TNC) is an extracellular matrix protein implicated in biological processes important for atherosclerotic plaque development and progression, including smooth muscle cell migration and proliferation. Previously, we observed differential expression of TNC in atherosclerotic aortas compared with healthy aortas. The goal of this study was to investigate whether common genetic variation within TNC is associated with risk of atherosclerosis and coronary artery disease (CAD) in three independent datasets. We genotyped 35 single nucleotide polymorphisms (SNPs), including 21 haplotype tagging SNPs, in two of these datasets: human aorta tissue samples (n?=?205) and the CATHGEN cardiovascular study (n?=?1,325). Eleven of these 35 SNPs were then genotyped in a third dataset, the GENECARD family study of early-onset CAD (n?=?879 families). Three SNPs representing a block of linkage disequilibrium, rs3789875, rs12347433, and rs4552883, were significantly associated with atherosclerosis in multiple datasets and demonstrated consistent, but suggestive, genetic effects in all analyses. In combined analysis rs3789875 and rs12347433 were statistically significant after Bonferroni correction for 35 comparisons, p?=?2?×?10^?6 and 5?×?10^?6, respectively. The SNP rs12347433 is a synonymous coding SNP and may be biologically relevant to the mechanism by which tenascin-C influences the pathophysiology of CAD and atherosclerosis. This is the first report of genetic association between polymorphisms in TNC and atherosclerosis or CAD.     

SYNE1-QK1 SNPs,G × G and G × E interactions on the risk of hyperlipidaemia

This study aimed to assess the relationship of 3 spectrin repeat containing nuclear envelope protein 1 (SYNE1) and 4 KH domain containing RNA binding (QK1) single nucleotide polymorphisms (SNPs), their haplotypes, gene-gene (G × G), gene-environment (G × E) interactions and hypercholesterolaemia (HCH) and hypertriglyceridaemia (HTG) in the Chinese Maonan minority. The genetic make-up of the SYNE1-QK1 SNPs in 1932 unrelated subjects (normal, 641; HCH, 649; and HTG, 642) was obtained by next-generation sequencing technologies. The genotypic frequencies of following SNPs were suggestively distinctive between the control and HCH groups (rs2623963, rs7745725, rs9459317, rs16897566), or between the control and HTG groups (rs2623963, rs1358317, rs7745725, rs1923608, rs16897566 SNPs; P < .05, respectively). Multiple-locus linkage disequilibrium analysis indicated that the identified SNPs were not inherited independently. Several haplotypes and gene-gene interaction haplotypes among the detected SNPs may be related with an increased morbidity of HCH (C-G-A, C-G-G and C-G-G-T-C-A-T) and HTG (C-G-G, G-T-G-C, C-G-G-G-T-G-C and C-G-G-T-C-A-T), whereas others may be related with an decreased risk of HCH (G-A-A, G-C-A-T, C-A-A-T-C-A-T and G-A-A-G-C-A-T) and HTG (G-A-A, G-C-A-T, C-A-A-T-C-A-T and G-A-A-G-C-A-T). The association evaluation based on haplotypes and gene-gene interactions could improve the power of detecting the risk of dyslipidaemia than anyone of SNP alone. There was significant three-locus model involving SNP-SNP, haplotype-haplotype/environment and G × G interactions (P < .05-0.001) that were detected by GMDR in HCH and HTG groups. Different interactions between genetic and environmental factors would produce different redundancy or synergy effects on the morbidity of HCH and/or HTG.     

Molecular genetic analysis of human homologs of Caenorhabditis elegans mab-21-like 1 gene in patients with neural tube defects

BACKGROUND: Neural tube defects (NTDs) are complex embryological malformations, affecting 1 in 1,000 live births. Antisense studies have implicated murine Mab21 genes as having an important role in neural tube development. We investigated whether MAB21L1/L2 genes could be involved in the aetiology of NTDs. METHODS: Denaturing HPLC (DHPLC) analysis of MAB21 genes was performed in 116 NTD cases. A case-control approach was used to test if the two single nucleotide polymorphisms (SNPs) of the MAB21L1 gene might be associated with increased NTD risk. RESULTS: No pathological variants of MAB21L1/L2 genes were identified by DHPLC analysis. Case-control studies demonstrated that the two SNPs (CAG triplets in 5'UTR; A-->C in 3'UTR) in the MAB21L1 gene are unlikely to be directly responsible for myelomeningocele. CONCLUSIONS: We suggest that MAB21 genes are unlikely to have substantial impact on NTDs. These preliminary findings will need to be investigated in larger samples before firm conclusions can be made.     

Family-based association analysis of theMAPT gene in Parkinson

The MAPT gene has been shown to be associated with several neurodegenerative disorders, including forms of parkinsonism and Parkinson disease (PD), but the results reveal population differences. We investigated the association of 10 single-nucleotide polymorphisms (SNPs) in the region ofMAPT on chromosome 17q21 with PD and age at onset, by using 443 discordant sib pairs in PD from a public dataset (Mayo-Perlegen LEAPS Collaboration). Association with PD was assessed by the FBAT using generalized estimating equations (FBAT-GEE), while the association with age at onset as a quantitative trait was evaluated using the FBAT-logrank statistic. Five SNPs were significantly associated with PD (P < 0.05) in an additive model, and 9 SNPs were associated with PD (P < 0.05) in dominant and recessive models. Interestingly, 8 PD-associated SNPs were also associated with age at onset of PD (P < 0.05) in dominant and recessive models. The SNP most significantly associated with PD and age at onset was rs17649641 (P = 0.015 and 0.021, respectively). Two-SNP haplotypes inferred from rs17563965 and rs17649641 also showed association with PD (P = 0.018) and age at onset (P = 0.026). These results provide further support for the role of MAPT in development of PD.     

Genetic risk variants for dyslexia on chromosome 18 in a German cohort

Dyslexia is characterized by impaired reading and spelling. The disorder has a prevalence of about 5% in Germany, and a strong hereditary component. Several loci are thought to be involved in the development of dyslexia. Scerri et al. identified eight potential dyslexia‐associated single nucleotide polymorphisms (SNPs) in seven genes on chromosome 18 in an English‐speaking population. Here, we present an association analysis that explores the relevance of these SNPs in a German population comprising 388 dyslexia cases and 364 control cases. In case–control analysis, three nominal SNP associations were replicated. The major alleles of NEDD4L‐rs12606138 and NEDD4L‐rs8094327 were risk associated [odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.0–1.7, P‐value = 0.017 and OR = 1.39, 95% CI = 1.1–1.7, P‐value = 0.007, respectively], and both SNPs were in strong linkage disequilibrium (r² = 0.95). For MYO5B‐rs555879, the minor allele was risk associated (OR = 1.31, 95% CI = 1.1–1.6, P‐value = 0.011). The combined analysis of SNP sets using set enrichment analysis revealed a study‐wide significant association for three SNPs with susceptibility for dyslexia. In summary, our results substantiate genetic markers in NEDD4L and MYO5B as risk factors for dyslexia and provide first evidence that the relevance of these markers is not restricted to the English language .