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1.  Genome-wide association study of maternal and inherited effects on left-sided cardiac malformations 
Human Molecular Genetics  2014;24(1):265-273.
Congenital left-sided lesions (LSLs) are serious, heritable malformations of the heart. However, little is known about the genetic causes of LSLs. This study was undertaken to identify common variants acting through the genotype of the affected individual (i.e. case) or the mother (e.g. via an in utero effect) that influence the risk of LSLs. A genome-wide association study (GWAS) was performed using data from 377 LSL case-parent triads, with follow-up studies in an independent sample of 224 triads and analysis of the combined data. Associations with both the case and maternal genotypes were assessed using log-linear analyses under an additive model. An association between LSLs and the case genotype for one intergenic SNP on chromosome 16 achieved genome-wide significance in the combined data (rs8061121, combined P = 4.0 × 10−9; relative risk to heterozygote: 2.6, 95% CI: 1.9–3.7). In the combined data, there was also suggestive evidence of association between LSLs and the case genotype for a variant in the synaptoporin gene (rs1975649, combined P = 3.4 × 10−7; relative risk to heterozygote: 1.6, 95% CI: 1.4–2.0) and between LSLs and the maternal genotype for an intergenic SNP on chromosome 10 (rs11008222, combined P = 6.3 × 10−7; relative risk to heterozygote: 1.6, 95% CI: 1.4–2.0). This is the first GWAS of LSLs to evaluate associations with both the case and maternal genotypes. The results of this study identify three candidate LSL susceptibility loci, including one that appears to be associated with the risk of LSLs via the maternal genotype.
PMCID: PMC4326325  PMID: 25138779
2.  Genetic sharing and heritability of paediatric age of onset autoimmune diseases 
Nature Communications  2015;6:8442.
Autoimmune diseases (AIDs) are polygenic diseases affecting 7–10% of the population in the Western Hemisphere with few effective therapies. Here, we quantify the heritability of paediatric AIDs (pAIDs), including JIA, SLE, CEL, T1D, UC, CD, PS, SPA and CVID, attributable to common genomic variations (SNP-h2). SNP-h2 estimates are most significant for T1D (0.863±s.e. 0.07) and JIA (0.727±s.e. 0.037), more modest for UC (0.386±s.e. 0.04) and CD (0.454±0.025), largely consistent with population estimates and are generally greater than that previously reported by adult GWAS. On pairwise analysis, we observed that the diseases UC-CD (0.69±s.e. 0.07) and JIA-CVID (0.343±s.e. 0.13) are the most strongly correlated. Variations across the MHC strongly contribute to SNP-h2 in T1D and JIA, but does not significantly contribute to the pairwise rG. Together, our results partition contributions of shared versus disease-specific genomic variations to pAID heritability, identifying pAIDs with unexpected risk sharing, while recapitulating known associations between autoimmune diseases previously reported in adult cohorts.
Autoimmune diseases are genetically complex disorders that affect up to 10% of the Western population. Here Li et al. quantify the heritability of a range of autoimmune diseases in the largest paediatric cohort examined to date, illustrating that genetic and non-genetic components variably contribute to the susceptibility of each disease.
PMCID: PMC4633631  PMID: 26450413
4.  Phenotype-specific association of the TGFBR3 locus with nonsyndromic cryptorchidism 
The Journal of urology  2014;193(5):1637-1645.
Based on a genome-wide association study (GWAS) of testicular dysgenesis syndrome (TDS) reporting possible association with TGFBR3, we analyzed GWAS data from a larger, phenotypically restricted cryptorchidism population for potential replication of this signal.
Materials and Methods
We excluded samples based on strict quality control criteria, leaving 844 cases and 2718 controls of European ancestry that were analyzed in 2 separate groups based on genotyping platform. Analyses included genotype imputation at the TGFBR3 locus, association analysis of imputed data with correction for population substructure, subsequent meta-analysis of Group 1 and 2 data and selective genotyping of independent cases (n=330) and controls (n=324) for replication. We also measured Tgfbr3 mRNA levels and performed TGFBR3/betaglycan immunostaining in rat fetal gubernaculum.
We identified suggestive (p≤1×10−4) association of markers in/near TGFBR3 including rs9661103 (OR 1.40, 95% CI 1.20,1.64, p=2.71×10−5) and rs10782968 (OR 1.58, CI 1.26,1.98, p=9.36×10−5) in Groups 1 and 2, respectively. In subgroup analyses, we observed strongest association of rs17576372 (OR 1.42, CI 1.24,1.60; p=1.67×10−4) with proximal and rs11165059 (OR 1.32, CI 1.15,1.38; p=9.42×10−4) with distal testis position, signals in strong linkage disequilibrium with rs9661103 and rs10782968, respectively. Association of the prior GWAS signal (rs12082710) was marginal (OR 1.13, CI 0.99,1.28, p=0.09 for Group 1) and we were unable to replicate signals in our independent cohort. Tgfbr3/betaglycan was differentially expressed in wild type and cryptorchid rat fetal gubernaculum.
These data suggest complex or phenotype-specific association of cryptorchidism with TGFBR3 and the gubernaculum as a potential target of TGFβ signaling.
PMCID: PMC4406821  PMID: 25390077
Cryptorchidism; genetic association studies; TGFRB3; gubernaculum
5.  Genome-wide copy number variation study associates metabotropic glutamate receptor gene networks with attention deficit hyperactivity disorder 
Nature genetics  2011;44(1):78-84.
Attention deficit hyperactivity disorder (ADHD) is a common, heritable neuropsychiatric disorder of unknown etiology. We performed a whole-genome copy number variation (CNV) study on 1,013 cases with ADHD and 4,105 healthy children of European ancestry using 550,000 SNPs. We evaluated statistically significant findings in multiple independent cohorts, with a total of 2,493 cases with ADHD and 9,222 controls of European ancestry, using matched platforms. CNVs affecting metabotropic glutamate receptor genes were enriched across all cohorts (P = 2.1 × 10−9). We saw GRM5 (encoding glutamate receptor, metabotropic 5) deletions in ten cases and one control (P = 1.36 × 10−6). We saw GRM7 deletions in six cases, and we saw GRM8 deletions in eight cases and no controls. GRM1 was duplicated in eight cases. We experimentally validated the observed variants using quantitative RT-PCR. A gene network analysis showed that genes interacting with the genes in the GRM family are enriched for CNVs in ~10% of the cases (P = 4.38 × 10−10) after correction for occurrence in the controls. We identified rare recurrent CNVs affecting glutamatergic neurotransmission genes that were overrepresented in multiple ADHD cohorts.
PMCID: PMC4310555  PMID: 22138692
6.  Association of variants of the interleukin-23 receptor (IL23R) gene with susceptibility to pediatric Crohn’s disease 
Background & Aims
Recently an association was demonstrated between the single nucleotide polymorphism (SNP), rs11209026, within the interleukin-23 receptor (IL23R) locus and Crohn’s disease (CD) as a consequence of a genome wide association study of this disease in adults. We examined the effects of this and other previously reported SNPs at this locus with respect to CD in children.
Utilizing data from our ongoing genome-wide association study in our cohort of 142 pediatric CD cases and 281 matched controls, we investigated the association of the previously reported SNPs at the IL23R locus with the childhood form of this disease.
Using a Fisher’s exact test, the minor allele frequency (MAF) of rs1120902 in the cases was 1.75% while it was 6.61% in controls, yielding a protective odds ratio (OR) of 0.25 (95% CI 0.10 – 0.65; one-sided P = 9.2×10−4). Furthermore, of all the SNPs previously reported, rs11209026 was the most strongly associated. A subsequent family-based association test (which is more resistant to population stratification) with 65 sets of trios derived from our initial patient cohort yielded significant association with rs11209026 in a transmission disequilibrium test (one-sided P=0.0017). In contrast, no association was detected to the CARD15 gene for the IBD phenotype.
The OR of the IL23R variant in our pediatric study is highly comparable with that reported previously in a non-Jewish adult IBD case-control cohort (OR=0.26). As such, variants in IL23R gene confer a similar magnitude of risk of CD to children as for their adult counterparts.
PMCID: PMC4287202  PMID: 17618837
IL23R; gene; association; Crohn’s Disease
8.  AGC1 Deficiency Causes Infantile Epilepsy, Abnormal Myelination, and Reduced N-Acetylaspartate 
JIMD Reports  2014;14:77-85.
Background: Whole exome sequencing (WES) offers a powerful diagnostic tool to rapidly and efficiently sequence all coding genes in individuals presenting for consideration of phenotypically and genetically heterogeneous disorders such as suspected mitochondrial disease. Here, we report results of WES and functional validation in a consanguineous Indian kindred where two siblings presented with profound developmental delay, congenital hypotonia, refractory epilepsy, abnormal myelination, fluctuating basal ganglia changes, cerebral atrophy, and reduced N-acetylaspartate (NAA).
Methods: Whole blood DNA from one affected and one unaffected sibling was captured by Agilent SureSelect Human All Exon kit and sequenced on the Illumina HiSeq2000. Mutations were validated by Sanger sequencing in all family members. Protein from wild-type and mutant fibroblasts was isolated to assess mutation effects on protein expression and enzyme activity.
Results: A novel SLC25A12 homozygous missense mutation, c.1058G>A; p.Arg353Gln, segregated with disease in this kindred. SLC25A12 encodes the neuronal aspartate-glutamate carrier 1 (AGC1) protein, an essential component of the neuronal malate/aspartate shuttle that transfers NADH and H+ reducing equivalents from the cytosol to mitochondria. AGC1 activity enables neuronal export of aspartate, the glial substrate necessary for proper neuronal myelination. Recombinant mutant p.Arg353Gln AGC1 activity was reduced to 15% of wild type. One prior reported SLC25A12 mutation caused complete loss of AGC1 activity in a child with epilepsy, hypotonia, hypomyelination, and reduced brain NAA.
Conclusions: These data strongly suggest that SLC25A12 disease impairs neuronal AGC1 activity. SLC25A12 sequencing should be considered in children with infantile epilepsy, congenital hypotonia, global delay, abnormal myelination, and reduced brain NAA.
Electronic supplementary material
The online version of this chapter (doi:10.1007/8904_2013_287) contains supplementary material, which is available to authorized users.
PMCID: PMC4213337  PMID: 24515575
9.  Common variants at 12q15 and 12q24 are associated with infant head circumference 
Taal, H Rob | Pourcain, Beate St | Thiering, Elisabeth | Das, Shikta | Mook-Kanamori, Dennis O | Warrington, Nicole M | Kaakinen, Marika | Kreiner-Møller, Eskil | Bradfield, Jonathan P | Freathy, Rachel M | Geller, Frank | Guxens, Mònica | Cousminer, Diana L | Kerkhof, Marjan | Timpson, Nicholas J | Ikram, M Arfan | Beilin, Lawrence J | Bønnelykke, Klaus | Buxton, Jessica L | Charoen, Pimphen | Chawes, Bo Lund Krogsgaard | Eriksson, Johan | Evans, David M | Hofman, Albert | Kemp, John P | Kim, Cecilia E | Klopp, Norman | Lahti, Jari | Lye, Stephen J | McMahon, George | Mentch, Frank D | Müller, Martina | O’Reilly, Paul F | Prokopenko, Inga | Rivadeneira, Fernando | Steegers, Eric A P | Sunyer, Jordi | Tiesler, Carla | Yaghootkar, Hanieh | Breteler, Monique M B | Debette, Stephanie | Fornage, Myriam | Gudnason, Vilmundur | Launer, Lenore J | van der Lugt, Aad | Mosley, Thomas H | Seshadri, Sudha | Smith, Albert V | Vernooij, Meike W | Blakemore, Alexandra IF | Chiavacci, Rosetta M | Feenstra, Bjarke | Fernandez-Benet, Julio | Grant, Struan F A | Hartikainen, Anna-Liisa | van der Heijden, Albert J | Iñiguez, Carmen | Lathrop, Mark | McArdle, Wendy L | Mølgaard, Anne | Newnham, John P | Palmer, Lyle J | Palotie, Aarno | Pouta, Annneli | Ring, Susan M | Sovio, Ulla | Standl, Marie | Uitterlinden, Andre G | Wichmann, H-Erich | Vissing, Nadja Hawwa | DeCarli, Charles | van Duijn, Cornelia M | McCarthy, Mark I | Koppelman, Gerard H. | Estivill, Xavier | Hattersley, Andrew T | Melbye, Mads | Bisgaard, Hans | Pennell, Craig E | Widen, Elisabeth | Hakonarson, Hakon | Smith, George Davey | Heinrich, Joachim | Jarvelin, Marjo-Riitta | Jaddoe, Vincent W V
Nature genetics  2012;44(5):532-538.
To identify genetic variants associated with head circumference in infancy, we performed a meta-analysis of seven genome-wide association (GWA) studies (N=10,768 from European ancestry enrolled in pregnancy/birth cohorts) and followed up three lead signals in six replication studies (combined N=19,089). Rs7980687 on chromosome 12q24 (P=8.1×10−9), and rs1042725 on chromosome 12q15 (P=2.8×10−10) were robustly associated with head circumference in infancy. Although these loci have previously been associated with adult height1, their effects on infant head circumference were largely independent of height (P=3.8×10−7 for rs7980687, P=1.3×10−7 for rs1042725 after adjustment for infant height). A third signal, rs11655470 on chromosome 17q21, showed suggestive evidence of association with head circumference (P=3.9×10−6). SNPs correlated to the 17q21 signal show genome-wide association with adult intra cranial volume2, Parkinson’s disease and other neurodegenerative diseases3-5, indicating that a common genetic variant in this region might link early brain growth with neurological disease in later life.
PMCID: PMC3773913  PMID: 22504419
10.  Evaluating the role of the FUS/TLS-related gene EWSR1 in amyotrophic lateral sclerosis 
Human Molecular Genetics  2012;21(13):2899-2911.
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting motor neurons. Mutations in related RNA-binding proteins TDP-43, FUS/TLS and TAF15 have been connected to ALS. These three proteins share several features, including the presence of a bioinformatics-predicted prion domain, aggregation–prone nature in vitro and in vivo and toxic effects when expressed in multiple model systems. Given these commonalities, we hypothesized that a related protein, EWSR1 (Ewing sarcoma breakpoint region 1), might also exhibit similar properties and therefore could contribute to disease. Here, we report an analysis of EWSR1 in multiple functional assays, including mutational screening in ALS patients and controls. We identified three missense variants in EWSR1 in ALS patients, which were absent in a large number of healthy control individuals. We show that disease-specific variants affect EWSR1 localization in motor neurons. We also provide multiple independent lines of in vitro and in vivo evidence that EWSR1 has similar properties as TDP-43, FUS and TAF15, including aggregation–prone behavior in vitro and ability to confer neurodegeneration in Drosophila. Postmortem analysis of sporadic ALS cases also revealed cytoplasmic mislocalization of EWSR1. Together, our studies highlight a potential role for EWSR1 in ALS, provide a collection of functional assays to be used to assess roles of additional RNA-binding proteins in disease and support an emerging concept that a class of aggregation–prone RNA-binding proteins might contribute broadly to ALS and related neurodegenerative diseases.
PMCID: PMC3373238  PMID: 22454397
11.  The missense variation landscape of FTO, MC4R and TMEM18 in obese children of African ancestry 
Obesity (Silver Spring, Md.)  2013;21(1):159-163.
Common variation at the loci harboring FTO, MC4R and TMEM18 is consistently reported as being statistically the most strongly associated with obesity. We investigated if these loci also harbor rarer missense variants that confer substantially higher risk of common childhood obesity in African American (AA) children. We sequenced the exons of FTO, MC4R and TMEM18 in an initial subset of our cohort i.e. 200 obese (BMI≥95th percentile) and 200 lean AA children (BMI≤5th percentile). Any missense exonic variants that were uncovered went on to be further genotyped in a further 768 obese and 768 lean (BMI≤50th percentile) children of the same ethnicity. A number of exonic variants were observed from our sequencing effort: seven in FTO, of which four were non-synonymous (A163T, G182A, M400V and A405V), thirteen in MC4R, of which six were non-synonymous (V103I, N123S, S136A, F202L, N240S and I251L) and four in TMEM18, of which two were non-synonymous (P2S and V113L). Follow-up genotyping of these missense variants revealed only one significant difference in allele frequency between cases and controls, namely with N240S in MC4R(Fisher's Exact P = 0.0001). In summary, moderately rare missense variants within the FTO, MC4R and TMEM18 genes observed in our study did not confer risk of common childhood obesity in African Americans except for a degree of evidence for one known loss-of-function variant in MC4R.
PMCID: PMC3605748  PMID: 23505181
Obesity; Pediatrics; Genomics
12.  Copy Number Variations in Alternative Splicing Gene Networks Impact Lifespan 
PLoS ONE  2013;8(1):e53846.
Longevity has a strong genetic component evidenced by family-based studies. Lipoprotein metabolism, FOXO proteins, and insulin/IGF-1 signaling pathways in model systems have shown polygenic variations predisposing to shorter lifespan. To test the hypothesis that rare variants could influence lifespan, we compared the rates of CNVs in healthy children (0–18 years of age) with individuals 67 years or older. CNVs at a significantly higher frequency in the pediatric cohort were considered risk variants impacting lifespan, while those enriched in the geriatric cohort were considered longevity protective variants. We performed a whole-genome CNV analysis on 7,313 children and 2,701 adults of European ancestry genotyped with 302,108 SNP probes. Positive findings were evaluated in an independent cohort of 2,079 pediatric and 4,692 geriatric subjects. We detected 8 deletions and 10 duplications that were enriched in the pediatric group (P = 3.33×10−8–1.6×10−2 unadjusted), while only one duplication was enriched in the geriatric cohort (P = 6.3×10−4). Population stratification correction resulted in 5 deletions and 3 duplications remaining significant (P = 5.16×10−5–4.26×10−2) in the replication cohort. Three deletions and four duplications were significant combined (combined P = 3.7×10−4−3.9×10−2). All associated loci were experimentally validated using qPCR. Evaluation of these genes for pathway enrichment demonstrated ∼50% are involved in alternative splicing (P = 0.0077 Benjamini and Hochberg corrected). We conclude that genetic variations disrupting RNA splicing could have long-term biological effects impacting lifespan.
PMCID: PMC3559729  PMID: 23382853
13.  Common variants at five new loci associated with early-onset inflammatory bowel disease 
Nature Genetics  2009;41(12):1335-1340.
The inflammatory bowel diseases (IBD) Crohn’s disease and ulcerative colitis are common causes of morbidity in children and young adults in the western world. Here we report the results of a genome-wide association study in early-onset IBD involving 3,426 affected individuals and 11,963 genetically matched controls recruited through international collaborations in Europe and North America, thereby extending the results from a previous study of 1,011 individuals with early-onset IBD1. We have identified five new regions associated with early-onset IBD susceptibility, including 16p11 near the cytokine gene IL27 (rs8049439, P = 2.41 × 10−9), 22q12 (rs2412973, P = 1.55 × 10−9), 10q22 (rs1250550, P = 5.63 × 10−9), 2q37 (rs4676410, P = 3.64 × 10−8) and 19q13.11 (rs10500264, P = 4.26 × 10−10). Our scan also detected associations at 23 of 32 loci previously implicated in adult-onset Crohn’s disease and at 8 of 17 loci implicated in adult-onset ulcerative colitis, highlighting the close pathogenetic relationship between early- and adult-onset IBD.
PMCID: PMC3267927  PMID: 19915574
14.  A Genome-Wide Meta-Analysis of Six Type 1 Diabetes Cohorts Identifies Multiple Associated Loci 
PLoS Genetics  2011;7(9):e1002293.
Diabetes impacts approximately 200 million people worldwide, of whom approximately 10% are affected by type 1 diabetes (T1D). The application of genome-wide association studies (GWAS) has robustly revealed dozens of genetic contributors to the pathogenesis of T1D, with the most recent meta-analysis identifying in excess of 40 loci. To identify additional genetic loci for T1D susceptibility, we examined associations in the largest meta-analysis to date between the disease and ∼2.54 million SNPs in a combined cohort of 9,934 cases and 16,956 controls. Targeted follow-up of 53 SNPs in 1,120 affected trios uncovered three new loci associated with T1D that reached genome-wide significance. The most significantly associated SNP (rs539514, P = 5.66×10−11) resides in an intronic region of the LMO7 (LIM domain only 7) gene on 13q22. The second most significantly associated SNP (rs478222, P = 3.50×10−9) resides in an intronic region of the EFR3B (protein EFR3 homolog B) gene on 2p23; however, the region of linkage disequilibrium is approximately 800 kb and harbors additional multiple genes, including NCOA1, C2orf79, CENPO, ADCY3, DNAJC27, POMC, and DNMT3A. The third most significantly associated SNP (rs924043, P = 8.06×10−9) lies in an intergenic region on 6q27, where the region of association is approximately 900 kb and harbors multiple genes including WDR27, C6orf120, PHF10, TCTE3, C6orf208, LOC154449, DLL1, FAM120B, PSMB1, TBP, and PCD2. These latest associated regions add to the growing repertoire of gene networks predisposing to T1D.
Author Summary
Despite the fact that there is clearly a large genetic component to type 1 diabetes (T1D), uncovering the genes contributing to this disease has proven challenging. However, in the past three years there has been relatively major progress in this regard, with advances in genetic screening technologies allowing investigators to scan the genome for variants conferring risk for disease without prior hypotheses. Such genome-wide association studies have revealed multiple regions of the genome to be robustly and consistently associated with T1D. More recent findings have been a consequence of combining of multiple datasets from independent investigators in meta-analyses, which have more power to pick up additional variants contributing to the trait. In the current study, we describe the largest meta-analysis of T1D genome-wide genotyped datasets to date, which combines six large studies. As a consequence, we have uncovered three new signals residing at the chromosomal locations 13q22, 2p23, and 6q27, which went on to be replicated in independent sample sets. These latest associated regions add to the growing repertoire of gene networks predisposing to T1D.
PMCID: PMC3183083  PMID: 21980299
15.  Examination of All Type 2 Diabetes GWAS Loci Reveals HHEX-IDE as a Locus Influencing Pediatric BMI 
Diabetes  2009;59(3):751-755.
A number of studies have found that BMI in early life influences the risk of developing type 2 diabetes later in life. Our goal was to investigate if any type 2 diabetes variants uncovered through genome-wide association studies (GWAS) impact BMI in childhood.
Using data from an ongoing GWAS of pediatric BMI in our cohort, we investigated the association of pediatric BMI with 20 single nucleotide polymorphisms at 18 type 2 diabetes loci uncovered through GWAS, consisting of ADAMTS9, CDC123-CAMK1D, CDKAL1, CDKN2A/B, EXT2, FTO, HHEX-IDE, IGF2BP2, the intragenic region on 11p12, JAZF1, KCNQ1, LOC387761, MTNR1B, NOTCH2, SLC30A8, TCF7L2, THADA, and TSPAN8-LGR5. We randomly partitioned our cohort exactly in half in order to have a discovery cohort (n = 3,592) and a replication cohort (n = 3,592).
Our data show that the major type 2 diabetes risk–conferring G allele of rs7923837 at the HHEX-IDE locus was associated with higher pediatric BMI in both the discovery (P = 0.0013 and survived correction for 20 tests) and replication (P = 0.023) sets (combined P = 1.01 × 10−4). Association was not detected with any other known type 2 diabetes loci uncovered to date through GWAS except for the well-established FTO.
Our data show that the same genetic HHEX-IDE variant, which is associated with type 2 diabetes from previous studies, also influences pediatric BMI.
PMCID: PMC2828649  PMID: 19933996
16.  Duplication of the SLIT3 Locus on 5q35.1 Predisposes to Major Depressive Disorder 
PLoS ONE  2010;5(12):e15463.
Major depressive disorder (MDD) is a common psychiatric and behavioral disorder. To discover novel variants conferring risk to MDD, we conducted a whole-genome scan of copy number variation (CNV), including 1,693 MDD cases and 4,506 controls genotyped on the Perlegen 600K platform. The most significant locus was observed on 5q35.1, harboring the SLIT3 gene (P = 2×10−3). Extending the controls with 30,000 subjects typed on the Illumina 550 k array, we found the CNV to remain exclusive to MDD cases (P = 3.2×10−9). Duplication was observed in 5 unrelated MDD cases encompassing 646 kb with highly similar breakpoints. SLIT3 is integral to repulsive axon guidance based on binding to Roundabout receptors. Duplication of 5q35.1 is a highly penetrant variation accounting for 0.7% of the subset of 647 cases harboring large CNVs, using a threshold of a minimum of 10 SNPs and 100 kb. This study leverages a large dataset of MDD cases and controls for the analysis of CNVs with matched platform and ethnicity. SLIT3 duplication is a novel association which explains a definitive proportion of the largely unknown etiology of MDD.
PMCID: PMC2995745  PMID: 21152026
17.  Common variants in HSPB7 and FRMD4B associated with advanced heart failure 
Heart failure results from abnormalities in multiple biological processes that contribute to cardiac dysfunction. We tested the hypothesis that inherited variation in genes of known importance to cardiovascular biology would thus contribute to heart failure risk.
Methods and Results
We utilized the ITMAT/Broad/CARe (IBC) cardiovascular SNP-array to screen referral populations of advanced heart failure patients for variants in ~2,000 genes of predicted importance to cardiovascular biology. Our design was a two-stage case-control study. In Stage 1, genotypes in Caucasian heart failure patients (n=1,590; ejection fraction 32±16%) were compared to those in unaffected controls (n=577; ejection fraction 67±8%) recruited from the same referral centers. Associations were tested for independent replication in Stage 2 (n=308 cases, 2,314 controls). Two intronic SNPs showed replicated associations with all-cause heart failure: rs1739843 in HSPB7 (combined P=3.09×10−6) and rs6787362 in FRMD4B (P=6.09×10−6). For both SNPs the minor allele was protective. In subgroup analyses, rs1739843 associated with both ischemic and nonischemic heart failure, whereas rs6787362 associated principally with ischemic heart failure. Linkage disequilibrium surrounding rs1739843 suggested that the causal variant resides in a region containing HSPB7 and a neighboring gene, CLCNKA, whereas the causal variant near rs6787362 is probably within FRMD4B. Allele frequencies for these SNPs were substantially different in African Americans (n=635 cases, 714 controls) and showed no association with heart failure in this population.
Our findings identify regions containing HSPB7 and FRMD4B as novel susceptibility loci for advanced heart failure. More broadly, in an era of genome-wide association studies, we demonstrate how knowledge of candidate genes can be leveraged as a complementary strategy to discern the genetics of complex disorders.
PMCID: PMC2957840  PMID: 20124441
cardiomyopathy; genetics; heart failure
18.  Examination of Type 2 Diabetes Loci Implicates CDKAL1 as a Birth Weight Gene 
Diabetes  2009;58(10):2414-2418.
A number of studies have found that reduced birth weight is associated with type 2 diabetes later in life; however, the underlying mechanism for this correlation remains unresolved. Recently, association has been demonstrated between low birth weight and single nucleotide polymorphisms (SNPs) at the CDKAL1 and HHEX-IDE loci, regions that were previously implicated in the pathogenesis of type 2 diabetes. In order to investigate whether type 2 diabetes risk–conferring alleles associate with low birth weight in our Caucasian childhood cohort, we examined the effects of 20 such loci on this trait.
Using data from an ongoing genome-wide association study in our cohort of 5,465 Caucasian children with recorded birth weights, we investigated the association of the previously reported type 2 diabetes–associated variation at 20 loci including TCF7L2, HHEX-IDE, PPARG, KCNJ11, SLC30A8, IGF2BP2, CDKAL1, CDKN2A/2B, and JAZF1 with birth weight.
Our data show that the minor allele of rs7756992 (P = 8 × 10−5) at the CDKAL1 locus is strongly associated with lower birth weight, whereas a perfect surrogate for variation previously implicated for the trait at the same locus only yielded nominally significant association (P = 0.01; r2 rs7756992 = 0.677). However, association was not detected with any of the other type 2 diabetes loci studied.
We observe association between lower birth weight and type 2 diabetes risk–conferring alleles at the CDKAL1 locus. Our data show that the same genetic locus that has been identified as a marker for type 2 diabetes in previous studies also influences birth weight.
PMCID: PMC2750235  PMID: 19592620
19.  Common genetic variants on 5p14.1 associate with autism spectrum disorders 
Nature  2009;459(7246):528-533.
Autism spectrum disorders (ASDs) represent a group of childhood neurodevelopmental and neuropsychiatric disorders characterized by deficits in verbal communication, impairment of social interaction, and restricted and repetitive patterns of interests and behaviour. To identify common genetic risk factors underlying ASDs, here we present the results of genome-wide association studies on a cohort of 780 families (3,101 subjects) with affected children, and a second cohort of 1,204 affected subjects and 6,491 control subjects, all of whom were of European ancestry. Six single nucleotide polymorphisms between cadherin 10 (CDH10) and cadherin 9 (CDH9)—two genes encoding neuronal cell-adhesion molecules—revealed strong association signals, with the most significant SNP being rs4307059 (P = 3.4 × 10−8, odds ratio = 1.19). These signals were replicated in two independent cohorts, with combined P values ranging from 7.4 × 10−8 to 2.1 × 10−10. Our results implicate neuronal cell-adhesion molecules in the pathogenesis of ASDs, and represent, to our knowledge, the first demonstration of genome-wide significant association of common variants with susceptibility to ASDs.
PMCID: PMC2943511  PMID: 19404256
20.  Autism genome-wide copy number variation reveals ubiquitin and neuronal genes 
Nature  2009;459(7246):569-573.
Autism spectrum disorders (ASDs) are childhood neurodevelopmental disorders with complex genetic origins1–4. Previous studies focusing on candidate genes or genomic regions have identified several copy number variations (CNVs) that are associated with an increased risk of ASDs5–9. Here we present the results from a whole-genome CNV study on a cohort of 859 ASD cases and 1,409 healthy children of European ancestry who were genotyped with ~550,000 single nucleotide polymorphism markers, in an attempt to comprehensively identify CNVs conferring susceptibility to ASDs. Positive findings were evaluated in an independent cohort of 1,336 ASD cases and 1,110 controls of European ancestry. Besides previously reported ASD candidate genes, such as NRXN1 (ref. 10) and CNTN4 (refs 11, 12), several new susceptibility genes encoding neuronal cell-adhesion molecules, including NLGN1 and ASTN2, were enriched with CNVs in ASD cases compared to controls (P = 9.5 × 10−3). Furthermore, CNVs within or surrounding genes involved in the ubiquitin pathways, including UBE3A, PARK2, RFWD2 and FBXO40, were affected by CNVs not observed in controls (P = 3.3 × 10−3). We also identified duplications 55 kilobases upstream of complementary DNA AK123120 (P = 3.6 × 10−6). Although these variants may be individually rare, they target genes involved in neuronal cell-adhesion or ubiquitin degradation, indicating that these two important gene networks expressed within the central nervous system may contribute to the genetic susceptibility of ASD.
PMCID: PMC2925224  PMID: 19404257
21.  The role of height-associated loci identified in genome wide association studies in the determination of pediatric stature 
BMC Medical Genetics  2010;11:96.
Human height is considered highly heritable and correlated with certain disorders, such as type 2 diabetes and cancer. Despite environmental influences, genetic factors are known to play an important role in stature determination. A number of genetic determinants of adult height have already been established through genome wide association studies.
To examine 51 single nucleotide polymorphisms (SNPs) corresponding to the 46 previously reported genomic loci for height in 8,184 European American children with height measurements. We leveraged genotyping data from our ongoing GWA study of height variation in children in order to query the 51 SNPs in this pediatric cohort.
Sixteen of these SNPs yielded at least nominally significant association to height, representing fifteen different loci including EFEMP1-PNPT1, GPR126, C6orf173, SPAG17, Histone class 1, HLA class III and GDF5-UQCC. Other loci revealed no evidence for association, including HMGA1 and HMGA2. For the 16 associated variants, the genotype score explained 1.64% of the total variation for height z-score.
Among 46 loci that have been reported to associate with adult height to date, at least 15 also contribute to the determination of height in childhood.
PMCID: PMC2894790  PMID: 20546612
22.  Common Variation in ISL1 Confers Genetic Susceptibility for Human Congenital Heart Disease 
PLoS ONE  2010;5(5):e10855.
Congenital heart disease (CHD) is the most common birth abnormality and the etiology is unknown in the overwhelming majority of cases. ISLET1 (ISL1) is a transcription factor that marks cardiac progenitor cells and generates diverse multipotent cardiovascular cell lineages. The fundamental role of ISL1 in cardiac morphogenesis makes this an exceptional candidate gene to consider as a cause of complex congenital heart disease. We evaluated whether genetic variation in ISL1 fits the common variant–common disease hypothesis. A 2-stage case-control study examined 27 polymorphisms mapping to the ISL1 locus in 300 patients with complex congenital heart disease and 2,201 healthy pediatric controls. Eight genic and flanking ISL1 SNPs were significantly associated with complex congenital heart disease. A replication study analyzed these candidate SNPs in 1,044 new cases and 3,934 independent controls and confirmed that genetic variation in ISL1 is associated with risk of non-syndromic congenital heart disease. Our results demonstrate that two different ISL1 haplotypes contribute to risk of CHD in white and black/African American populations.
PMCID: PMC2877111  PMID: 20520780
23.  The role of obesity-associated loci identified in genome wide association studies in the determination of pediatric BMI 
Obesity (Silver Spring, Md.)  2009;17(12):2254-2257.
The prevalence of obesity in children and adults in the United States has increased dramatically over the past decade. Besides environmental factors, genetic factors are known to play an important role in the pathogenesis of obesity. A number of genetic determinants of adult BMI have already been established through genome wide association studies. In this study, we examined 25 single nucleotide polymorphisms (SNPs) corresponding to thirteen previously reported genomic loci in 6,078 children with measures of BMI. Fifteen of these SNPs yielded at least nominally significant association to BMI, representing nine different loci including INSIG2, FTO, MC4R, TMEM18, GNPDA2, NEGR1, BDNF, KCTD15 and 1q25. Other loci revealed no evidence for association, namely at MTCH2, SH2B1, 12q13 and 3q27. For the 15 associated variants, the genotype score explained 1.12% of the total variation for BMI z-score. We conclude that among thirteen loci that have been reported to associate with adult BMI, at least nine also contribute to the determination of BMI in childhood as demonstrated by their associations in our pediatric cohort.
PMCID: PMC2860782  PMID: 19478790
24.  Investigation of the locus near MC4R with childhood obesity in Americans of European and African ancestry 
Obesity (Silver Spring, Md.)  2009;17(7):1461-1465.
Recently a modest, but consistently, replicated association was demonstrated between obesity and the single nucleotide polymorphism (SNP), rs17782313, 3’ of the MC4R locus as a consequence of a meta-analysis of genome wide association (GWA) studies of the disease in Caucasian populations. We investigated the association in the context of the childhood form of the disease utilizing data from our ongoing GWA study in a cohort of 728 European American (EA) obese children (BMI ≥ 95th percentile) and 3,960 EA controls (BMI < 95th percentile), as well as 1,008 African American (AA) obese children and 2,715 AA controls. rs571312, rs10871777 and rs476828 (perfect surrogates for rs17782313) yielded odds ratios in the EA cohort of 1.142 (P = 0.045), 1.137 (P = 0.054) and 1.145 (P = 0.042); however, there was no significant association with these SNPs in the AA cohort. When investigating all thirty SNPs present on the Illumina BeadChip at this locus, again there was no evidence for association in AA cases when correcting for the number of tests employed. As such, variants 3’ to the MC4R locus present on the genotyping platform utilized confer a similar magnitude of risk of obesity in Caucasian children as to their adult Caucasian counterparts but this observation did not extend to African Americans.
PMCID: PMC2860794  PMID: 19265794
25.  Follow-Up Analysis of Genome-Wide Association Data Identifies Novel Loci for Type 1 Diabetes 
Diabetes  2009;58(1):290-295.
OBJECTIVE—Two recent genome-wide association (GWA) studies have revealed novel loci for type 1 diabetes, a common multifactorial disease with a strong genetic component. To fully utilize the GWA data that we had obtained by genotyping 563 type 1 diabetes probands and 1,146 control subjects, as well as 483 case subject–parent trios, using the Illumina HumanHap550 BeadChip, we designed a full stage 2 study to capture other possible association signals.
RESEARCH DESIGN AND METHODS—From our existing datasets, we selected 982 markers with P < 0.05 in both GWA cohorts. Genotyping these in an independent set of 636 nuclear families with 974 affected offspring revealed 75 markers that also had P < 0.05 in this third cohort. Among these, six single nucleotide polymorphisms in five novel loci also had P < 0.05 in the Wellcome Trust Case-Control Consortium dataset and were further tested in 1,303 type 1 diabetes probands from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) plus 1,673 control subjects.
RESULTS—Two markers (rs9976767 and rs3757247) remained significant after adjusting for the number of tests in this last cohort; they reside in UBASH3A (OR 1.16; combined P = 2.33 × 10−8) and BACH2 (1.13; combined P = 1.25 × 10−6).
CONCLUSIONS—Evaluation of a large number of statistical GWA candidates in several independent cohorts has revealed additional loci that are associated with type 1 diabetes. The two genes at these respective loci, UBASH3A and BACH2, are both biologically relevant to autoimmunity.
PMCID: PMC2606889  PMID: 18840781

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