Association of Alzheimer’s-Related Gene Variants with Autism Spectrum Disorder: A Case–Control Study in an Iraqi Cohort

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that manifests as difficulties in social communication and the presence of restricted and repetitive behaviors. The etiology remains obscure, although there is increasing evidence of shared neurodevelopmental and neurodegenerative disorder pathways. This study aimed to determine whether gene variants previously linked to Alzheimer’s disease (AD) have a role in ASD susceptibility. Within a case–control framework, we studied a sample of 270 Iraqi children, 135 with ASD and 135 age-matched controls aged 6–12 years. T-ARMS PCR was used to determine the genotypes of five selected polymorphisms NECTIN2 (rs6859), CR1 (rs670173), CLU (rs7982), ABCA7 (rs3764650), and BIN1 (rs744373) that have been associated with AD. The polymorphism genotype and allele frequencies were analyzed using the chi-square test, and odds ratio analysis with 95% confidence intervals was conducted. Age and sex-stratified analyses in addition to biochemical profiling were also conducted. Significant associations with ASD were found for three polymorphisms: CR1 rs670173 (p = 0.007), CLU rs7982 (p = 0.010), and BIN1 rs744373 (p = 0.013). The male-to-female effect ratio was stronger than the female-to-male. Interestingly, younger boys aged 6 to 9 years demonstrated the most pronounced effect of CLU rs7982 (OR = 1.92, 95% CI: 1.25–2.94, p = 0.003). NECTIN2 rs6859 (p = 0.543) and ABCA7 rs3764650 (p = 0.102) did not yield significant associations. Biochemical parameters showed no significant differences among the groups. Our results imply that some AD-associated gene variants, especially those related to neuroinflammation and synaptic activity, could elevate the risk for ASD. This reinforces the notion of shared genetic risk factors between neurodevelopmental and neurodegenerative disorders, likely involving common mechanisms for the formation and maintenance of neural circuits.