SCN4B and Huntington disease: In particular, the sodium channel beta‐4 subunit (Scn4b) is one of the first genes downregulated in SPNs in Q175 mice and in HD (CHDI Foundation Provided Disclosure Notice 1; Oyama et al., 2006), is strongly responsive to CAG repeat length (CHDI personal communication), and is a prominent node in striatal transcriptional networks driven by repeat length identified in studies of an allelic series of HD knock‐in mice (CHDI personal communication).