Genome Wide Association Study in the New Haven Lexinome Project IdentifiesGARRE1as a Novel Gene for Reading Performance

Despite high prevalence and high heritability, few candidate genes have been identified for reading disability. To identify novel genetic variants we performed a genome-wide association study (GWAS) using high-depth whole genome sequencing and predicated on reading performance in 407 subjects enrolled in a longitudinal study of response-to-intervention, called the New Haven Lexinome Project. The primary GWAS identified a single peak of 31 SNPs on chromosome 19 that achieved the threshold for genome-wide significance (rs2599553 P =3.13×10 −8 ) located over an expression quantitative trait locus (eQTL) for GARRE1 (Granule Associated Rac And RHOG Effector 1). Little is known about the function of GARRE1 , except that it is highly and developmentally expressed in human cerebellum relative to cortex. Local ancestry regression showed the strongest association for the lead variant in African or Admixed American populations, who have been under-represented in previous genetic studies of reading. We replicated our chromosome 19 results in the Genes, Reading, and Dyslexia (GRaD) cohort and found a moderating effect of age with implications for the consideration of developmental effects in the design of future analyses. Growth curve modeling demonstrated that minor alleles of the lead SNP are related to reading longitudinally from Grade 1 to Grade 5, and that children with at least 1 minor allele of rs2599553 persistently underperformed relative to their peers by 0.33 to 0.5 standard deviations on standardized assessments of non-word decoding and reading fluency. Significance Statement To the best of our knowledge, this work represents the only GWAS predicated on longitudinal reading performance data. Starting with initial discovery, we replicate our association in a second cohort, address common causes of type I error, localize the signal to a single gene, implicate a region of the brain most likely to be affected by variation in our candidate, show a gene-by-age effect with implications for study design in this field, and demonstrate that minor alleles of our lead SNP are associated with significant and persistent clinical effects on reading development in children.