Catalog of 238 variations among six human genes encoding solute carriers (hSLCs) in the Japanese population

We screened DNAs of 48 Japanese individuals for single-nucleotide polymorphisms (SNPs) in six genes encoding proteins of the solute carrier (SLC) family by direct sequencing of their entire genomic regions except for repetitive-sequence elements. This approach identified 213 SNPs and 25 insertion/deletion polymorphisms among the six genes. On average, we identified 1 SNP in every 509 nucleotides. Of the 213 SNPs, 14 were identified in the SLC10A1 gene, 51 in SLC15A1, 29 in SLC22A1, 27 in SLC22A2, 54 in SLC22A4, and 38 in SLC22A5. Eight were located in 5′ flanking regions, 172 in introns, 25 in exons, and 8 in 3′ flanking regions. These variants should contribute to investigations of possible correlations between genotypes and phenotypes as regards disease susceptibilities or responsiveness to drug therapy. Received: July 24, 2002 / Accepted: July 25, 2002 Correspondence to:Y. Nakamura     

Identification of susceptibility SNPs in CTLA-4 and PTPN22 for scleritis in Han Chinese

The aim of this study was to determine the association between 13 single nucleotide polymorphisms (SNPs) in the cytotoxic T lymphocyte-associated antigen-4 (CTLA4) and protein tyrosine phosphatase non-receptor type 22 (PTPN22) genes with scleritis in a Chinese Han population. We recruited 432 scleritis patients and 710 healthy controls. Four tag SNPs of CTLA4 and nine tag SNPs of PTPN22 were selected using Haploview. Genotyping was performed with the Sequenom MassArray® iPLEX GOLD Assay. Genotype and allele frequency differences were analyzed by χ² test and Bonferroni correction. Haplotype analysis was performed to further evaluate the association of these two genes with scleritis. In this study, CTLA4/rs3087243 G allele frequency and GG genotype frequency were significantly increased in scleritis patients compared to healthy controls [corrected P-value (Pc) = 0·02, odds ratio (OR) = 1·475, 95% confidence interval (CI) = 1·175–1·851; Pc = 0·04, OR = 1·546, 95% CI = 1·190–2·008, respectively]. None of the tested SNPs in the PTPN22 gene showed an association with scleritis. Haplotype analysis revealed a lower frequency of a CTLA4 TCAA haplotype (order of SNPs: rs733618, rs5742909, rs231775, rs3087243) (Pc = 4·26 × 10^–3, OR = 0·618, 95% CI = 0·540–0·858) and a higher frequency of a PTPN22 TTATACGCG haplotype (order of SNPs: rs3789604, rs150426536, rs1746853, rs1217403, rs1217406, rs3789609, rs1217414, rs3789612, rs2488457) (Pc = 2·83 × 10^–4, OR = 1·457, 95% CI = 1·210-1·754) in scleritis patients when compared to healthy controls. In conclusion, our findings indicate that CTLA4 and PTPN22 might confer genetic susceptibility to scleritis in a Chinese Han population.     

Immunohistochemical detection of a specific receptor for lipocalin2 (solute carrier family 22 member 17, SLC22A17) and its prognostic significance in endometrial carcinoma

Background

We previously reported the overexpression of lipocalin2 (LCN2), a 25 kDa secretory protein involved in iron-transportation, in endometrial carcinoma and its possible contribution to endometrial carcinogenesis. Recently, a specific receptor for LCN2, solute carrier family 22 member 17 (SLC22A17), was identified. The present study was undertaken to investigate the expression of SLC22A17 in endometrial carcinoma.

Methods

The expression of the SLC22A17 and LCN2 proteins was examined immunohistochemically using 69 cases of endometrial carcinoma and adjacent normal endometrial tissues. Immunoreactivity was evaluated according to the percentage of positive cells and described as a positivity index (PI, full score 100).

Results

The expression of SLC22A17 was negligible in normal endometria, but positive staining for SLC22A17 (PI ≧ 1) was observed in 35 cases of endometrial carcinoma. The PI for SLC22A17 was significantly higher in cases with histological grade 3 (P < 0.0005), advanced FIGO stage (P = 0.002), deep myometrial invasion (P = 0.029), positive lymph-vascular space invasion (P = 0.029), positive intraperitoneal cytology (P = 0.020) and adnexal metastasis (P = 0.029). The expression of SLC22A17 and LCN2 was positively correlated with a significant difference (P = 0.002), and the patients who overexpressed both SLC22A17 and LCN2 showed poorer survival than those without the expression of SLC22A17 or LCN2 (P = 0.002). Moreover, the overexpression of both SLC22A17 and LCN2 was indicated to be an independent prognostic factor by multivariable analysis.

Conclusions

These results suggested that SLC22A17, in cooperation with LCN2, to be involved in the acquisition of aggressive behavior among endometrial carcinoma cells.     

Direct or indirect association in a complex disease: the role of SLC22A4 and SLC22A5 functional variants in Crohn disease

A common haplotype spanning 250 kb on chromosome 5q31 is strongly associated with Crohn disease (CD). Recently, two functional variants within the SLC22A4 and SLC22A5 genes at this locus (IBD5), L503F (c.1507C > T) and G-207C (c.-207G > C), have been proposed to contribute directly to susceptibility to CD. However, extensive linkage disequilibrium at the IBD5 locus has complicated efforts to distinguish causal variants from association of the general risk haplotype. We genotyped the SLC22A4 and SLC22A5 variants and other polymorphisms across the risk haplotype in four populations of European origin, and applied regression-based haplotype analysis to over 1,200 fully genotyped case-control pairs, modeling case/control status on the presence of one or more SNPs to test for conditional association and to identify risk haplotypes. We found highly significant association of SNPs at the IBD5 locus with Crohn disease in all populations tested. However, the frequencies of L503F and G-207C in individuals who did not carry the general IBD5 risk haplotype were not significantly different in cases and controls, with associated disease odds ratios (ORs) of 0.90 (95% CI, 0.57-1.40) and 0.90 (95% CI, 0.65-1.23), respectively. Haplotype analysis showed that addition of the SLC22A4 and SLC22A5 variants to a null model that included the background risk haplotype did not significantly improve the model fit. In addition to the common risk haplotype, several rare haplotypes had an increased frequency in cases compared to controls. This study suggests that the molecular basis for Crohn disease susceptibility at the IBD5 locus remains to be defined, and highlights the challenge of the identification of causal variants in a complex disease in regions of extensive linkage disequilibrium.     

Association analysis of <Emphasis Type="Italic">SLC22A4</Emphasis>, <Emphasis Type="Italic">SLC22A5</Emphasis> and <Emphasis Type="Italic">DLG5</Emphasis> in Japanese patients with Crohn disease

Crohn disease (CD) is an inflammatory bowel disease characterized by chronic transmural, segmental, and typically granulomatous inflammation of the gut. Recently, two novel candidate gene loci associated with CD, SLC22A4 and SLC22A5 on chromosome 5 known as IBD5 and DLG5 on chromosome 10, were identified through association analysis of Caucasian CD patients. We validated these candidate genes in Japanese patients with CD and found a weak but possible association with both SLC22A4 (P=0.028) and DLG5 (P=0.023). However, the reported genetic variants that were indicated to be causative in the Caucasian population were completely absent in or were not associated with Japanese CD patients. These findings imply significant differences in genetic background with CD susceptibility among different ethnic groups and further indicate some difficulty of population-based studies.     

Associations of single nucleotide polymorphisms of PTPN22 and Ctla4 genes with the risk of allergic rhinitis in a Chinese Han population

Background

Allergic rhinitis (AR) is an inflammatory disorder of the upper airway. Protein tyrosine phosphatase non-receptor 22 encoded by PTPN22 gene and cytotoxic T-lymphocyte associated 4 encoded by Ctla4 gene are associated with autoimmune diseases.

Replication of reported genetic associations of PADI4, FCRL3, SLC22A4 and RUNX1 genes with rheumatoid arthritis: results of an independent Japanese population and evidence from meta-analysis of East Asian studies

We conducted population-based association tests for the four selected SNPs (rs2240340/padi4_94, rs7528684/fcrl3_3, rs3792876/slc2F2 and rs2268277/runx1) previously reported to be associated with rheumatoid arthritis (RA). The study population consisted of 950 unrelated Japanese subjects with RA and 507 controls, none of whom had previously been tested for these variants. Only the SNP rs2240340/padi4_94 was modestly associated with RA [allele odds ratio (OR) 1.22, 95% confidence interval (CI) 1.04–1.43, P = 0.012]. The most significant association effect was found for genotype contrast between minor and major allele homozygotes (OR 1.53, 95% CI 1.10–2.12, P = 0.010). No other SNPs showed a statistically significant association with RA in our population. Meta-analysis of published studies and our new data confirmed a highly significant association between PADI4 gene SNPs and increased risk of RA in East Asian populations (allele fixed-effects summary OR 1.31, 95% CI 1.22–1.41, P < 0.0001). We found some evidence for an association of either rs7528684/fcrl3_3 or rs3792876/slc2F2 with RA; however, because the magnitudes of effects were apparently much weaker than those reported in the initial positive reports, and there were substantial levels of inter-study OR heterogeneity, we concluded that additional studies are needed to fully understand the present results. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The association of PTPN22 (rs2476601) and IL2RA (rs11594656) polymorphisms with T1D in Egyptian children

BackgroundType 1 diabetes mellitus (T1D) is a T cell-mediated autoimmune disease characterized by the destruction of pancreatic β cells. PTPN22 and IL2RA polymorphisms have been found to be associated with several autoimmune diseases including T1D.AimsWe aimed to elucidate the role of PTPN22 and IL2RA polymorphisms in predisposition of T1D in Egyptian children.MethodsWe studied 150 children and adolescents with T1D and 165 healthy controls. The PTPN22 (rs2476601) and IL2RA (rs11594656) polymorphisms were genotyped using polymerase chain reaction.ResultsWe found that carriers of the T allele of PTPN22 were significantly more likely to develop T1D (OR = 2.2, 95% CI = 1.2–4, P = 0.01). Also, the carrier of TT genotype and T allele of IL2RA more likely to develop T1D (OR = 2.8, 1.4, respectively, P = 0.03). There was a statistically significant association between T allele of PTPN22 gene and females ⩽10 years old at the onset of diabetes (OR = 4, 95% CI = 1.2–13.4, P = 0.019).ConclusionThis study suggests a possible association between the T allele of PTPN22 gene and TT genotype of IL2RA with T1D in studied Egyptian children, especially, females with early onset diabetes who carried the 1858T allele.     

SLC22A12基因第8外显子和第8内含子多态与中国汉族人原发性高尿酸血症关联研究

目的 研究原发性高尿酸血症患者SLC22AI2基因第8内含子和第8外显子单核苷酸多态(single nucleotide polymorphism,SNP)位点与原发性高尿酸血症遗传易感性的关系.方法 选择山东沿海地区原发性高尿酸血症患者215例,正常对照人群323名.提取基因组DNA,PCR扩增SLC22A12基因第8内含子和第8外显子,对PCR扩增产物进行测序.结果 序列分析发现:(1)SLC22AI2基因第8外显子存在T1309C单核苷酸多态,第8内含子存在-103A＞G单核苷酸多态,这2个多态位点完全连锁.(2)高尿酸血症组-103A＞G G等位基因频率和T1309C C等位基因频率明显高于正常对照组(均为51.9%vs.42.4%,P＜0.01);(3)高尿酸血症组GG+GA基因型频率和CC+CT基因型频率显著高于正常对照组(均为80.0%vs.69.0%,P＜0.01).(4)-103 A＞G和T1309C基因多态中,含有等位基因G的基因型GG+GA及含有等位基因C的基因型CC+CT均使高尿酸血症的发病危险性上升了1.79倍(OR=1.79,95%CI:1.19～2.70).结论 SLC22A12基因第8外显子T130gC及第8内含子-103A＞G SNP与原发性高尿酸血症密切相关.     

Manifestation of recessive combined D‐2‐, L‐2‐hydroxyglutaric aciduria in combination with 22q11.2 deletion syndrome

22q11.2 deletion syndrome is one of the most common human microdeletion syndromes. The clinical phenotype of 22q11.2 deletion syndrome is variable, ranging from mild to life‐threatening symptoms, depending mainly on the extent of the deleted region. Brain malformations described in association with 22q11.2 deletion syndrome include polymicrogyria, cerebellar hypoplasia, megacisterna magna, and agenesis of the corpus callosum (ACC), although these are rare. We report here for the first time a patient who manifested combined D‐2‐ and L‐2‐hydroxyglutaric aciduria as a result of a hemizygous mutation in SLC25A1 in combination with 22q11.2 deletion. The girl was diagnosed to have ACC shortly after birth and a deletion of 22q11.2 was identified by genetic analysis. Although the patient showed cardiac anomalies, which is one of the typical symptoms of 22q11.2 deletion syndrome, her rather severe phenotype and atypical face prompted us to search for additional pathogenic mutations. Three genes present in the deleted 22q11.2 region, SLC25A1, TUBA8, and SNAP29, which have been reported to be associated with brain malformation, were analyzed for the presence of pathogenic mutations. A frameshift mutation, c.18_24dup (p.Ala9Profs*82), was identified in the first exon of the remaining SLC25A1 allele, resulting in the complete loss of normal SLC25A1 function in the patient's cells. Our results support the notion that the existence of another genetic abnormality involving the retained allele on 22q11.2 should be considered when atypical or rare phenotypes are observed.

     

CD28 and PTPN22 are associated with susceptibility to rheumatoid arthritis in Egyptians

ObjectiveLimited data are available on the genetics of rheumatoid arthritis (RA) in Egyptians. Therefore, we investigated whether the confirmed genetic risk factors for RA in Europeans and/or Asians contribute to RA susceptibility in Egyptians.Subjects and methodsA set of seven single-nucleotide polymorphisms (SNPs) in the vicinity of CD28, TNFAIP3, PTPN22, PADI4 and HLA-DRA were tested in a large multi-centric RA cohort in Egypt, consisting of 394 cases and 398 matched controls. Patients were stratified based on the positivity of either anti-citrullinated protein antibodies (ACPAs) or rheumatoid factor (RF).ResultsSignificant association was evident for three SNPs in this cohort: the CD28 (rs1980422) variant showed a strong association in the whole cohort (P = 0.000119) and in seropositive subsets of the disease (P_ACPA+ = 0.004; P_RF+ = 0.0005). Upon stratification, the PTPN22 (rs2476601) and TNFAIP3(rs5029939) variants showed association only with ACPA positive (P_ACPA+ = 0.00573) and negative (P_ACPA− = 0.00999) phenotypes, respectively.ConclusionOur results suggest that CD28(rs1980422) and PTPN22(rs2476601) contribute to RA-susceptibility in Egyptians. Failure to replicate the association of PADI4(rs2240340)/(PADI4_94) in Egyptian RA patients provides further support for the notion that genetic architecture of RA is different in multiple populations of European, Asian, African, and Middle Eastern ancestries. Further investigation using large-scale studies is thus needed to maximize the power of genetic association.     

A 129‐kb Deletion on Chromosome 12 Confers Substantial Protection Against Rheumatoid Arthritis,Implicating the Gene SLC2A3

We describe a copy‐number variant (CNV) for which deletion alleles confer a protective affect against rheumatoid arthritis (RA). This CNV reflects net unit deletions and expansions to a normal two‐unit tandem duplication located on human chr12p13.31, a region with conserved synteny to the rat RA susceptibility quantitative trait loci Oia2. Genotyping, using the paralogue ratio test and SNP intensity data, in Swedish samples (2,403 cases, 1,269 controls) showed that the frequency of deletion variants is significantly lower in cases (P = 0.0012, OR = 0.442 [95%CI 0.258–0.755]). Reduced frequencies of deletion variants were also seen in replication materials comprising 9,201 UK samples (1,846 cases, 7,355 controls) and 2,963 US samples (906 controls, 1,967 cases) (Mantel–Haenszel P = 0.036, OR = 0.559 [95%CI 0.323–0.966]). Combining the three datasets produces a Mantel–Haenszel OR of 0.497 (P < 0.0002). The deletion variant lacks 129‐kb of DNA containing SLC2A3, NANOGP1, and SLC2A14. SLC2A3 encodes a high‐affinity glucose transporter important in the immune response and chondrocyte metabolism, both key aspects of RA pathogenesis. The large effect size of this association, its potential relevance to other diseases in which SLC2A3 is implicated, and the possibility of targeting drugs to inhibit SLC2A3, argue for further examination of the genetics and the biology of this CNV.     

Meta-analysis reveals PTPN22 1858C/T polymorphism confers susceptibility to rheumatoid arthritis in Caucasian but not in Asian population

The PTPN22 1858C/T polymorphism is associated with rheumatoid arthritis (RA). However, reports from the Asian populations are conflicting in nature and lacks consensus. The aim of our study was to evaluate the association between the PTPN22 1858C/T polymorphism and RA in Asian and Caucasian subjects by carrying out a meta-analysis of Asian and Caucasian data. A total of 27?205 RA cases and 27?677 controls were considered in the present meta-analysis involving eight Asian and 35 Caucasian studies. The pooled odds ratios (ORs) were performed for the allele, dominant, and recessive genetic model. No statistically significant association was found between the PTPN22 1858C/T polymorphism and risk of RA in Asian population (allele genetic model: OR?=?1.217, 95% confidence interval (CI)?=?0.99–1.496, p value 0.061; dominant genetic model: OR?=?1.238, 95% CI?=?0.982–1.562, p value 0.071; recessive genetic model: OR?=?1.964, 95% CI?=?0.678–5.693, p value 0.213). A significant association with risk of RA in Caucasian population suggesting that T–– allele does confer susceptibility to RA in this subgroup was observed (allele genetic model: OR?=?1.638, 95% CI?=?1.574–1.705, p value p value p value PTPN22 1858C/T polymorphism is not associated with RA risk in Asian populations. However, our meta-analysis confirms that the PTPN22 1858C/T polymorphism is associated with RA susceptibility in Caucasians.     

Polymorphisms of <Emphasis Type="Italic">PTPN11</Emphasis> Coding SHP-2 as Biomarkers for Ulcerative Colitis Susceptibility in the Japanese Population

Objective  To identify genetic determinants of inflammatory bowel disease (IBD), we examined an association between polymorphisms of both the programmed cell death 1 gene (PDCD1) and the src homology 2 domain-containing tyrosine phosphatase 2 gene (PTPN11) and susceptibility to IBD. Methods  Study subjects comprised 114 patients with ulcerative colitis (UC), 83 patients with Crohn’s disease, and 200 healthy control subjects. Five single nucleotide polymorphisms (SNPs) in PDCD1 and PTPN11 were detected by polymerase chain reaction restriction fragment length polymorphism. Subsequently, haplotypes composed of the two SNPs in PTPN11 were constructed. Results  The frequencies of the Hap 1 haplotype and its homozygous Hap 1/Hap 1 diplotype of PTPN11 were significantly increased in UC patients compared to control subjects (P = 0.011 and P = 0.030, respectively). While no association was found for PDCD1 for UC or CD and none for PTPN11 for CD. Conclusion   PTPN11 is a genetic determinant for the pathogenesis of UC, and haplotyping of PTPN11 may be useful as a genetic biomarker to identify high-risk individuals susceptible to UC.     

PTPN22 Single-Nucleotide Polymorphisms in Iranian Patients with Type 1 Diabetes Mellitus

Background: PTPN22 plays a crucial role in regulating the function of various cells of the immune system, particularly T cells. Polymorphisms of the PTPN22 gene have been associated with many autoimmune diseases, including type 1 diabetes (T1D) which is a T-cell-mediated disease.

Objective: The present study was aimed at genotyping of an Iranian population for five polymorphisms of the PTPN22 gene.

Methods: The study population consisted of 99 T1D patients and 100 healthy controls. We genotyped five single-nucleotide polymorphisms (SNPs) (rs12760457, rs1310182, rs1217414, rs33996649, and rs2476601) of the PTPN22 gene.

Results: Regarding the variant rs2476601, genotypes AG and GG were increased and decreased in T1D patients compared with controls, respectively. Further, alleles G and A of this SNP were found to be decreased and increased in T1D patients, respectively (p value = 0.001). However, T1D and control groups did not differ on genotype distribution or allele frequency for other investigated SNPs.

Conclusions: The PTPN22 rs2476601 minor allele (A) was associated with T1D in Iran, accounting for its pathophysiology in autoimmune diseases.     

Genetics of Rheumatoid Arthritis — A Comprehensive Review

The “Bermuda triangle” of genetics, environment and autoimmunity is involved in the pathogenesis of rheumatoid arthritis (RA). Various aspects of genetic contribution to the etiology, pathogenesis and outcome of RA are discussed in this review. The heritability of RA has been estimated to be about 60 %, while the contribution of HLA to heritability has been estimated to be 11–37 %. Apart from known shared epitope (SE) alleles, such as HLA-DRB1*01 and DRB1*04, other HLA alleles, such as HLA-DRB1*13 and DRB1*15 have been linked to RA susceptibility. A novel SE classification divides SE alleles into S1, S2, S3P and S3D groups, where primarily S2 and S3P groups have been associated with predisposition to seropositive RA. The most relevant non-HLA gene single nucleotide polymorphisms (SNPs) associated with RA include PTPN22, IL23R, TRAF1, CTLA4, IRF5, STAT4, CCR6, PADI4. Large genome-wide association studies (GWAS) have identified more than 30 loci involved in RA pathogenesis. HLA and some non-HLA genes may differentiate between anti-citrullinated protein antibody (ACPA) seropositive and seronegative RA. Genetic susceptibility has also been associated with environmental factors, primarily smoking. Some GWAS studies carried out in rodent models of arthritis have confirmed the role of human genes. For example, in the collagen-induced (CIA) and proteoglycan-induced arthritis (PgIA) models, two important loci — Pgia26/Cia5 and Pgia2/Cia2/Cia3, corresponding the human PTPN22/CD2 and TRAF1/C5 loci, respectively — have been identified. Finally, pharmacogenomics identified SNPs or multiple genetic signatures that may be associated with responses to traditional disease-modifying drugs and biologics.     

Non-HLA genes modulate the risk of rheumatoid arthritis associated with HLA-DRB1 in a susceptible North American Native population

Most of the genetic risk for rheumatoid arthritis (RA) is conferred by 'shared epitope' (SE), encoding alleles of HLA-DRB1. Specific North American Native (NAN) populations have RA prevalence rates of 2-5%, representing some of the highest rates estimated worldwide. As many NAN populations also demonstrate a high background frequency of SE, we sought to determine whether other genetic factors contribute to disease risk in this predisposed population. RA patients (n=333) and controls (n=490) from the Cree/Ojibway NAN population in Central Canada were HLA-DRB1 typed and tested for 21 single-nucleotide polymorphisms (SNPs) that have previously been associated with RA, including PTPN22, TRAF1-C5, CTLA4, PADI4, STAT4, FCRL3, CCL21, MMEL1-TNFRSF14, CDK6, PRKCQ, KIF5A-PIP4K2C, IL2RB, TNFAIP3, IL10-1082G/A and REL. Our findings indicate that SE is prevalent and represents a major genetic risk factor for RA in this population (82% cases versus 68% controls, odds ratio=2.2, 95% confidence interval 1.6-3.1, P<0.001). We also demonstrate that in the presence of SE, the minor allele of MMEL1-TNFRSF14 significantly reduces RA risk in a dominant manner, whereas TRAF1-C5 increases the risk. These findings point to the importance of non-HLA genes in determining RA risk in a population with a high frequency of disease predisposing HLA-DRB1 alleles.     

Meta‐analysis of association between obsessive‐compulsive disorder and the 3′ region of neuronal glutamate transporter gene SLC1A1

The neuronal glutamate transporter gene SLC1A1 is a candidate gene for obsessive‐compulsive disorder (OCD) based on linkage studies and convergent evidence implicating glutamate in OCD etiology. The 3′ end of SLC1A1 is the only genomic region with consistently demonstrated OCD association, especially when analyzing male‐only probands. However, specific allele associations have not been consistently replicated, and recent OCD genome‐wide association and meta‐analysis studies have not incorporated all previously associated SLC1A1 SNPs. To clarify the nature of association between SLC1A1 and OCD, pooled analysis was performed on all available relevant raw study data, comprising a final sample of 815 trios, 306 cases and 634 controls. This revealed weak association between OCD and one of nine tested SLC1A1 polymorphisms (rs301443; uncorrected P = 0.046; non‐significant corrected P). Secondary analyses of male‐affecteds only (N = 358 trios and 133 cases) demonstrated modest association between OCD and a different SNP (rs12682807; uncorrected P = 0.012; non‐significant corrected P). Findings of this meta‐analysis are consistent with the trend of previous candidate gene studies in psychiatry and do not clarify the putative role of SLC1A1 in OCD pathophysiology. Nonetheless, it may be important to further examine the potential associations demonstrated in this amalgamated sample, especially since the SNPs with modest associations were not included in the more highly powered recent GWAS or in a past meta‐analysis including five SLC1A1 polymorphisms. This study underscores the need for much larger sample sizes in future genetic association studies and suggests that next‐generation sequencing may be beneficial in examining the potential role of rare variants in OCD. © 2013 Wiley Periodicals, Inc.