Distal myopathy and rapidly progressive dementia associated with a novel mutation in the VCP gene: Expanding inclusion body myopathy with early-onset Paget disease and frontotemporal dementia spectrum.

Distal myopathies are a clinically and genetically heterogeneous group characterized by distal weakness at onset. Distal myopathies are classified according to age of onset, inheritance pattern, clinical features and molecular diagnosis. Inclusion body myopathy with early-onset Paget disease and fronto-temporal dementia is a rare adult late-onset disease related to valosin-containing protein gene mutations with an autosomal dominance inheritance. It is characterized by the triad of progressive myopathy, early-onset Paget disease and premature fronto-temporal dementia We report a severe phenotype in a Portuguese patient, related to a novel mutation in the valosin-containing protein gene, characterized by a severe late-onset distal myopathy and a rapidly progressive cognitive dysfunction suggesting fronto-temporal dementia. The patient did not manifest Paget disease. Family history was negative. This case emphasizes the importance of considering inclusion body myopathy with early-onset Paget disease and fronto-temporal dementia in the differential diagnosis of distal myopathies, even in the absence of family history.