LRRK2 gene mutation⁃associated semantic variant primary progressive aphasia: one case report and literatures review

Abstract

Objective To report the clinical phenotype and gene mutation characteristics of a case with leucine⁃rich repeat kinase 2 (LRRK2) gene mutation⁃associated semantic variant primary progressive aphasia. Methods and Results The clinical data of a patient with language comprehension impairment as the first symptom were analyzed, including clinical manifestations, neuropsychological and linguistic assessments, cerebrospinal fluid biomar kertests, brain images and genetic testings. We made a systematic discussion in combination with relevant literatures. The results showed that the main clinical manifestations of the patient were difficulty in understanding words and difficulty in finding words. Aphasia Battery of Chinese test showed that the temporal lobe damage was prominent. Head MRI showed asymmetric atrophy of the bilateral frontal and temporal lobes, which was significant on the left side. 18F⁃FDG PET further suggested that the glucose metabolism in the bilateral anterior temporal lobes and bilateral frontal lobes was reduced. Cognitive impairment and dyskinesia gene detection revealed thatthe patient had a heterozygous mutation in exon 25 3468G>C of LRRK2 gene, which was the first report at home and abroad. The clinical diagnosis was semantic variant primary progressive aphasia. Conclusions This patient carries mutations in the LRRK2 gene. It is likely that due to changes in the structure and function of the encoded LRRK2 protein, which causes tau pathologic changes, and in turn leads to the degeneration and atrophy of the frontotemporallobe and semantic variant primary progressive aphasia. The discovery ofthis gene mutation expands the gene mutation spectrum of frontotemporal lobe dege⁃neration.

DOI：10.3969/j.issn.1672⁃6731.2020.06.012