SORL1 mutations are associated with parkinsonian and psychiatric features in Alzheimer disease: Case reports

RATIONALE: The sortilin-related receptor 1 gene (SORL1) encodes a key protein (SORLA) involved in the pathophysiology of Alzheimer disease (AD). SORLA also mediates a trophic pathway that acts through glial cell line-derived neurotrophic factor (GDNF), a critical survival factor for the midbrain dopaminergic (DA) neurons. PATIENT CONCERNS: Four patients presented to our hospital with complaints of progressive memory decline, who developed extrapyramidal signs (EPS) and psychiatric symptoms. DIAGNOSES: All 4 patients were diagnosed with AD based on their symptoms, findings from cranial magnetic resonance imaging, and cerebrospinal fluid analysis. INTERVENTIONS: We also performed whole-exome sequencing (WES) and found 4 novel mutations in SORL1. Donepezil, rivastigmine, memantine, madopar, quetiapine, and risperidone were administrated as therapy. OUTCOMES: The four mutations would change the thermal stability of SORLA domain. This could be associated with parkinsonian and psychiatric features in AD. These patients showed improvements in parkinsonian and psychiatric features. LESSONS: These cases suggest that SORL1 mutations might result in aggregation of a-synuclein through altered function of GDNF and further lead to appearance of core dementia with Lewy bodies features.