Dyslexia susceptibility genes influence brain atrophy in frontotemporal dementia

Abstract

Objective: In this study, we evaluated whether variations within genes specifically associated with dyslexia, namely KIAA0319, DCDC2, and CNTNAP2, were associated with greater damage of language-related regions in patients with frontotemporal dementia (FTD) and primary progressive aphasia (PPA) in particular. Methods: A total of 118 patients with FTD, 84 with the behavioral variant of FTD (bvFTD) and 34 with PPA, underwent neuropsychological examination, genetic analyses, and brain MRI. KIAA0319 rs17243157 G/A, DCDC2 rs793842 A/G, and CNTNAP2 rs17236239 A/G genetic variations were assessed. Patients were grouped according to clinical phenotype and genotype status (GA/AA or GG). Gray matter (GM) and white matter (WM) differences were assessed by voxel-based morphometry and structural intercorrelation pattern analyses. Results: Patients carrying KIAA0319 A∗ (GA or AA) showed greater GM and WM atrophy in the left middle and inferior temporal gyri, as compared with KIAA0319 GG (p, 0.001). The effect of KIAA0319 polymorphism was mainly reported in patients with PPA. In patients with PPA carrying at-risk polymorphism, temporal damage led to loss of interhemispheric and intrahemispheric GM and WM structural association. No effect of DCDC2 and CNTNAP2 was found. Conclusions: Genes involved in dyslexia susceptibility, such as KIAA0319, result in language network vulnerability in FTD, and in PPA in particular.