Clinicopathologic variability of the GRN A9D mutation, including amyotrophic lateral sclerosis

We examined the clinical and pathologic phenotypes of GRN mutation carriers with the pathogenic A9D (g.26C>A) missense mutation.

Three patients with GRN A9D mutations were evaluated clinically and came to autopsy with subsequent neuropathologic examination.

The clinical diagnoses of patients with GRN A9D mutations were amyotrophic lateral sclerosis, atypical extrapyramidal disorder, and behavioral variant frontotemporal dementia. Immunohistochemistry for TAR DNA-binding protein 43 (TDP-43) revealed variability in morphology and distribution of pathology. One patient had notable involvement of motor neurons in the spinal cord as well as type B TDP-43, whereas 2 other patients had type A TDP-43.

The clinical presentation of the GRN A9D missense mutation is not restricted to behavioral variant frontotemporal dementia and may include aphasia, extrapyramidal features, and, notably, amyotrophic lateral sclerosis.