This subgroup analysis does not fully resolve neuroanatomical subtyping of molecularly defined bvFTD: case numbers across subgroups were small (precluding, for example, differentiation of individual mutations within each subgroup) while certain key bvFTD phenotypes (in particular, bvFTD due to progranulin gene mutations and sporadic forms of bvFTD associated syndromes of atypical parkinsonism or motor neurone disease) were either underrepresented or not represented at all. Here, GRN is linked to motor neuron disorder.