• At-risk variant in TCF7L2 for type II diabetes increases risk of schizophrenia.

      Hansen, Thomas; Ingason, Andrés; Djurovic, Srdjan; Melle, Ingrid; Fenger, Mogens; Gustafsson, Omar; Jakobsen, Klaus D; Rasmussen, Henrik B; Tosato, Sarah; Rietschel, Marcella; et al. (Elsevier, 2011-07-01)
      BACKGROUND: Schizophrenia is associated with increased risk of type II diabetes and metabolic disorders. However, it is unclear whether this comorbidity reflects shared genetic risk factors, at-risk lifestyle, or side effects of antipsychotic medication. METHODS: Eleven known risk variants of type II diabetes were genotyped in patients with schizophrenia in a sample of 410 Danish patients, each matched with two healthy control subjects on sex, birth year, and month. Replication was carried out in a large multinational European sample of 4089 patients with schizophrenia and 17,597 controls (SGENE+) using Mantel-Haenszel test. RESULTS: One type II diabetes at-risk allele located in TCF7L2, rs7903146 [T], was associated with schizophrenia in the discovery sample (p = .0052) and in the replication with an odds ratio of 1.07 (95% confidence interval 1.01-1.14, p = .033). CONCLUSION: The association reported here with a well-known diabetes variant suggests that the observed comorbidity is partially caused by genetic risk variants. This study also demonstrates how genetic studies can successfully examine an epidemiologically derived hypothesis of comorbidity.
    • Loss-of-function mutations in SLC30A8 protect against type 2 diabetes.

      Flannick, Jason; Thorleifsson, Gudmar; Beer, Nicola L; Jacobs, Suzanne B R; Grarup, Niels; Burtt, Noël P; Mahajan, Anubha; Fuchsberger, Christian; Atzmon, Gil; Benediktsson, Rafn; et al. (Nature Publishing Group, 2014-04)
      Loss-of-function mutations protective against human disease provide in vivo validation of therapeutic targets, but none have yet been described for type 2 diabetes (T2D). Through sequencing or genotyping of ~150,000 individuals across 5 ancestry groups, we identified 12 rare protein-truncating variants in SLC30A8, which encodes an islet zinc transporter (ZnT8) and harbors a common variant (p.Trp325Arg) associated with T2D risk and glucose and proinsulin levels. Collectively, carriers of protein-truncating variants had 65% reduced T2D risk (P = 1.7 × 10(-6)), and non-diabetic Icelandic carriers of a frameshift variant (p.Lys34Serfs*50) demonstrated reduced glucose levels (-0.17 s.d., P = 4.6 × 10(-4)). The two most common protein-truncating variants (p.Arg138* and p.Lys34Serfs*50) individually associate with T2D protection and encode unstable ZnT8 proteins. Previous functional study of SLC30A8 suggested that reduced zinc transport increases T2D risk, and phenotypic heterogeneity was observed in mouse Slc30a8 knockouts. In contrast, loss-of-function mutations in humans provide strong evidence that SLC30A8 haploinsufficiency protects against T2D, suggesting ZnT8 inhibition as a therapeutic strategy in T2D prevention.
    • Maternally derived microduplications at 15q11-q13: implication of imprinted genes in psychotic illness.

      Ingason, Andrés; Kirov, George; Giegling, Ina; Hansen, Thomas; Isles, Anthony R; Jakobsen, Klaus D; Kristinsson, Kari T; le Roux, Louise; Gustafsson, Omar; Craddock, Nick; et al. (American Psychiatric Association, 2011-04)
      OBJECTIVE: Rare copy number variants have been implicated in different neurodevelopmental disorders, with the same copy number variants often increasing risk of more than one of these phenotypes. In a discovery sample of 22 schizophrenia patients with an early onset of illness (10-15 years of age), the authors observed in one patient a maternally derived 15q11-q13 duplication overlapping the Prader-Willi/Angelman syndrome critical region. This prompted investigation of the role of 15q11-q13 duplications in psychotic illness. METHOD: The authors scanned 7,582 patients with schizophrenia or schizoaffective disorder and 41,370 comparison subjects without known psychiatric illness for copy number variants at 15q11-q13 and determined the parental origin of duplications using methylation-sensitive Southern hybridization analysis. RESULTS: Duplications were found in four case patients and five comparison subjects. All four case patients had maternally derived duplications (0.05%), while only three of the five comparison duplications were maternally derived (0.007%), resulting in a significant excess of maternally derived duplications in case patients (odds ratio=7.3). This excess is compatible with earlier observations that risk for psychosis in people with Prader-Willi syndrome caused by maternal uniparental disomy is much higher than in those caused by deletion of the paternal chromosome. CONCLUSIONS: These findings suggest that the presence of two maternal copies of a fragment of chromosome 15q11.2-q13.1 that overlaps with the Prader-Willi/Angelman syndrome critical region may be a rare risk factor for schizophrenia and other psychoses. Given that maternal duplications of this region are among the most consistent cytogenetic observations in autism, the findings provide further support for a shared genetic etiology between autism and psychosis.
    • Meta-analysis of heterogeneous data sources for genome-scale identification of risk genes in complex phenotypes.

      Pers, Tune H; Hansen, Niclas Tue; Lage, Kasper; Koefoed, Pernille; Dworzynski, Piotr; Miller, Martin Lee; Flint, Tracey J; Mellerup, Erling; Dam, Henrik; Andreassen, Ole A; et al. (Wiley-Blackwell, 2011-07)
      Meta-analyses of large-scale association studies typically proceed solely within one data type and do not exploit the potential complementarities in other sources of molecular evidence. Here, we present an approach to combine heterogeneous data from genome-wide association (GWA) studies, protein-protein interaction screens, disease similarity, linkage studies, and gene expression experiments into a multi-layered evidence network which is used to prioritize the entire protein-coding part of the genome identifying a shortlist of candidate genes. We report specifically results on bipolar disorder, a genetically complex disease where GWA studies have only been moderately successful. We validate one such candidate experimentally, YWHAH, by genotyping five variations in 640 patients and 1,377 controls. We found a significant allelic association for the rs1049583 polymorphism in YWHAH (adjusted P = 5.6e-3) with an odds ratio of 1.28 [1.12-1.48], which replicates a previous case-control study. In addition, we demonstrate our approach's general applicability by use of type 2 diabetes data sets. The method presented augments moderately powered GWA data, and represents a validated, flexible, and publicly available framework for identifying risk genes in highly polygenic diseases. The method is made available as a web service at www.cbs.dtu.dk/services/metaranker.
    • No clinical utility of KRAS variant rs61764370 for ovarian or breast cancer.

      Hollestelle, Antoinette; van der Baan, Frederieke H; Berchuck, Andrew; Johnatty, Sharon E; Aben, Katja K; Agnarsson, Bjarni A; Aittomäki, Kristiina; Alducci, Elisa; Andrulis, Irene L; Anton-Culver, Hoda; et al. (Academic Press Inc Elsevier Science, 2016-05)
      Clinical genetic testing is commercially available for rs61764370, an inherited variant residing in a KRAS 3' UTR microRNA binding site, based on suggested associations with increased ovarian and breast cancer risk as well as with survival time. However, prior studies, emphasizing particular subgroups, were relatively small. Therefore, we comprehensively evaluated ovarian and breast cancer risks as well as clinical outcome associated with rs61764370.
    • Severe osteoarthritis of the hand associates with common variants within the ALDH1A2 gene and with rare variants at 1p31.

      Styrkarsdottir, Unnur; Thorleifsson, Gudmar; Helgadottir, Hafdis T; Bomer, Nils; Metrustry, Sarah; Bierma-Zeinstra, S; Strijbosch, Annelieke M; Evangelou, Evangelos; Hart, Deborah; Beekman, Marian; et al. (Nature, 2014-05)
      Osteoarthritis is the most common form of arthritis and is a major cause of pain and disability in the elderly. To search for sequence variants that confer risk of osteoarthritis of the hand, we carried out a genome-wide association study (GWAS) in subjects with severe hand osteoarthritis, using variants identified through the whole-genome sequencing of 2,230 Icelanders. We found two significantly associated loci in the Icelandic discovery set: at 15q22 (frequency of 50.7%, odds ratio (OR) = 1.51, P = 3.99 × 10(-10)) in the ALDH1A2 gene and at 1p31 (frequency of 0.02%, OR = 50.6, P = 9.8 × 10(-10)). Among the carriers of the variant at 1p31 is a family with several members in whom the risk allele segregates with osteoarthritis. The variants within the ALDH1A2 gene were confirmed in replication sets from The Netherlands and the UK, yielding an overall association of OR = 1.46 and P = 1.1 × 10(-11) (rs3204689).