| Abstract | Schizophrenia (SZ) is a severe mental disorder characterized by multiple neurodevelopmental dysfunctions including a breakdown of thinking process and a deficit of typical emotional responses. Ataxin-2 (ATXN2) plays vital roles in cell proliferation and growth, and functional mutations of ATXN2 cause neurodegenerative phenotypes, including spinocerebellar ataxia type 2 (SCA2) and amyotrophic lateral sclerosis (ALS). To explore the possible role of ATXN2 in SZ, we conducted a two-stage study to examine the association of ATXN2 polymorphisms with SZ in the Han Chinese population. Association analysis of seven SNPs in 768 patients and 1348 controls revealed two associated SNPs, including rs630511 (P=1.76E-4) and rs7969300 (P=5.08E-4). We examined these two SNPs in a validation sample of 1957 patients and 1509 controls, and observed an association of rs7969300 with SZ (P=5.03E-3). The SNP rs7969300 is a non-synonymous SNP causing a Ser to Asn substitution, which is predicted to increase the protein stability of ATXN2. Our data suggest that the ATXN2 gene may confer vulnerability for SZ, adding further evidence for the genetic variants within the developmental pathway in the illness. |
| Abstract | People's differences in cognitive functions are partly heritable and are associated with important life outcomes. Previous genome-wide association (GWA) studies of cognitive functions have found evidence for polygenic effects yet, to date, there are few replicated genetic associations. Here we use data from the UK Biobank sample to investigate the genetic contributions to variation in tests of three cognitive functions and in educational attainment. GWA analyses were performed for verbal-numerical reasoning (N=36?035), memory (N=112?067), reaction time (N=111?483) and for the attainment of a college or a university degree (N=111?114). We report genome-wide significant single-nucleotide polymorphism (SNP)-based associations in 20 genomic regions, and significant gene-based findings in 46 regions. These include findings in the ATXN2, CYP2DG, APBA1 and CADM2 genes. We report replication of these hits in published GWA studies of cognitive function, educational attainment and childhood intelligence. There is also replication, in UK Biobank, of SNP hits reported previously in GWA studies of educational attainment and cognitive function. GCTA-GREML analyses, using common SNPs (minor allele frequency>0.01), indicated significant SNP-based heritabilities of 31% (s.e.m.=1.8%) for verbal-numerical reasoning, 5% (s.e.m.=0.6%) for memory, 11% (s.e.m.=0.6%) for reaction time and 21% (s.e.m.=0.6%) for educational attainment. Polygenic score analyses indicate that up to 5% of the variance in cognitive test scores can be predicted in an independent cohort. The genomic regions identified include several novel loci, some of which have been associated with intracranial volume, neurodegeneration, Alzheimer's disease and schizophrenia. |
