Atypical features including acquired oculomotor apraxia in <i>C9orf72</i> -associated familial primary lateral sclerosis

This family's presentation expands on sparse reports of <i>C9orf72</i>-associated PLS. The proband showcases a severity of ocular motor deficits not yet reported in PLS, extending ocular motor findings in MND. These deficits also provide clinical evidence of degeneration outside the motor cortex/spinal cord in PLS. The symptomatology (laryngeal dystonia, rapid progression) clinically overlaps with ALS/FTD, suggesting PLS may lie on the ALS-FTD spectrum. The severity and atypicality of this case also support suggestions that <i>C9orf72</i> mutations amplify the spectrum/severity of disease observed in TDP-43 proteinopathies.