C9orf72 and frontotemporal dementia: More recently, Sha et al. found that delusions were the presenting neuropsychiatric symptom in 21% of patients with bvFTD with an expansion in C9orf72, in 18% of patients with FTD and motor neuron disease (FTD-MND) carrying the C9orf72 mutation, and in 10.5% of the FTD-MND non-carrier (63).