Objective: DYX1C1 has been identified as a susceptible candidate gene for developmental dyslexia (DD); studies in various populations have yielded inconclusive results and the causal allele is unknown in the Indian population. On the basis of the initial association studies and the role of DYX1C1 in neuronal migration, we investigated the role of DYX1C1 in causing DD in an Indian population.
Materials and methods: Ten single-nucleotide polymorphisms (SNPs) of DYX1C1 were genotyped in 210 cases with DD and 256 age-matched nondyslexic controls. Genotyping of these SNPs was carried with the MassARRAY technique using SpectroCHIP and analysed with MALDI-TOF MS. Single-marker and two-marker haplotype analyses were carried out and the χ2-test, odds ratios, 95% confidence intervals and Yates correction were applied to identify the significance of the genotyped SNPs.
Results: A significant association was observed for the homozygous genotype (GG) of the SNP rs12899331 (3.12%) and individual allele frequency (P=0.039). Psycholinguistic tests showed an association between rs12899331 with dyslexic phenotypes such as word and nonword reading, syllable reversal task, spoonerism task and spelling. Two-marker haplotype analysis also showed a significant association for the markers G/C at rs12899331/rs1075938 (P=0.039) with the phenotypes rapid naming ability and phonological awareness, as well as with word reading, spelling and sentence repetition.
Conclusion: The promoter SNP rs12899331 of DYX1C1 may contribute towards the manifestation of DD. This study supports the association of DYX1C1 with DD in an Indian population.