Impact of APOE and MAPT genetic profile on the cognitive functions among Amyotrophic Lateral Sclerosis Tunisian patients

Amyotrophic Lateral Sclerosis(ALS) has traditionally been managed as a neuromuscular disorder. However, recent evidence suggests involvement of non-motor domains. This study aims to evaluate the impact of APOE and MAPT genotypes on the cognitive features of ALS. We included confirmed ALS cases from the Neurology department at Razi University Hospital, Tunisia. APOE and MAPT screening were conducted with Sanger sequencing validation, and preliminary screening for four main ALS genes was performed. Clinical phenotypes and genotypes were analyzed using appropriate tests, with healthy controls (HC) representing the Tunisian population. Two-hundred-seventy ALS patients were included, stratified as 213 spinal cases,49 with bulbar onset and 8 patients with generalized form with 140 HC. Regarding APOE, we reported high frequency of ALS cases carrier of APOE-ε4 isoform compared to controls(p < 0.0001).We found a significant association between APOE-ɛ4 and ALS onset site (p = 0.05,r = 0.33),with higher frequencies in bulbar onset patients. Cognitive signs were more frequent in ɛ4 carriers (r = 0.43,p < 0.01),and a significant link was observed between dysexecutive functions and the APOE risk allele (p = 0.0495).Concerning the MAPT haplotypes, we reported high frequency of ALS cases carrier of MAPT H1-haplotype HC (94.45% and 72.14% respectively, p < 0.001).Among ALS cases,MAPT-H1 showed a stronger positive correlation with the presence of oculomotor signs(p = 0.05,r = 0.28).As well as significant positive association between cognitive impairments(p = 0.039,r = 0.59). Our findings emphasize the correlation between APOE and MAPT genotypes and the cognitive features in our ALS patients. We also observed other interesting, though weak, significant correlations (with coefficients not exceeding 0.20),which require further validation in a larger cohort to confirm our results.