Amyotrophic lateral sclerosis with primary progressive aphasia: a case report and literature review

The association between amyotrophic lateral sclerosis (ALS) and primary progressive aphasia (PPA) is rarely seen in patients. A case of ALS-PPA with a possible reticulon 2 (RTN2) mutation was reported in this study. Moreover, we systematically reviewed the previous reports of 28 ALS cases with progressive non-fluent aphasia (PNFA) and semantic dementia (SD) to identified the unique pathologic features and strong heritability of ALS-PPA. There is a different heritability among the ALS-SD, ALS-PNFA, and the ALS-unclassified PPA groups (p=0.003). Males are more prone to have ALS-PPA than females in all the three groups (p=0.028). PPA-ALS usually starts with cognitive impairment, and the onset most often involves the bulbar. In addition, chromosome 9 open reading frame 72(C9ORF72) and TANK-binding kinase 1 (TBK1) are important pathogenic genes of PPA-ALS. Overall, heritability is of high certainty in ALS-SD, ALS-PNFA, and the ALS-unclassified PPA groups. TAR (Trans-Activator Regulatory) DNA-binding Protein 43 (TDP43) is a 100% predictive pathologic protein of ALS-PPA. C9ORF72 and TBK1 are important pathogenic genes of PPA-ALS.