ABSTRACT
Objective:To report a case with frontotemporal dementia (FTD) characterized by involuntary laughter.Methods:The clinical manifestations and imaging characteristics of a patient diagnosed as FTD was analyzed. Then the results of cerebrospinal fluid, positron emission tomography-computed tomography (PET-CT) and single-photon emission computed tomography examinations were collected. Blood samples were tested for related genes of FTD.Results:The patient is a 66 years old woman with insidious onset and progressing symptoms and she was mainly manifested as laughing out loud involuntarily when looking at others, childishness, stubbornness, loss of interest, irritability and other personal changes. Mild motor and language disorders were also manifested as moving slowly and speaking unclearly. The magnetic resonance imaging showed the atrophy of bilateral frontal, temporal lobe and bilateral hippocampal while the image of PET-CT showed the metabolism was reduced in different degrees. Eventually, behavioural variant of FTD was diagnosed. The result of ANXA11 gene sequencing revealed the mutation of c.107C>G(p.P36R).Conclusions:This is the first case in which a heterozygous mutation of ANXA11 gene, which is related to amyotrophic lateral sclerosis (ALS), is found in simple FTD patient, suggesting that ANXA11 gene may play an important role in the pathogenesis of FTD. This further supports the theory that ALS and FTD are spectrum disorders.