Last, mutation of tyrosyl‐DNA phosphodiesterase 1 (TDP1), a gene that resolves DNA replication stress because of abortive topoisomerase reactions and associated strand breaks,72 causes spinocerebellar ataxia with axonal neuropathy type 1 (SCAN1), a slowly progressive cerebellar ataxia and sensorimotor polyneuropathy.73 Here, TDP1 is linked to Spinocerebellar ataxia type 1 with axonal neuropathy.