In another family, we found slight motor involvement, cataract, cluster headache and lower limb motor impairment in a mother, and lower motor neuron disease in a grandmother, as well as stiff legs, urinary urgency, and slight cerebellar involvement with bipolar disorder in a daughter harboring the same mutation in KIF1A. Given that we are expanding the ways in which we genotype HSP patients, we should no longer be surprised to encounter an increasing variety of features associated with the condition. Here, KIF1A is linked to bipolar disorder.