ATN1 and Huntington disease: The most common HD phenocopies or HD-like syndromes are seen in STR expansions within C9orf72 [111] (discussed below), however, others include PRNP (Huntington disease-like 1, HDL1), JPH3 (HDL2), TBP (SCA17 or HDL4), ATXN8 (SCA8), FXN (Friedreich’s ataxia) and ATN1 (DRPLA), in addition to sequencing variants/deletions in VPS13A, TITF1, ADCY5, RNF216 and FRRS1L [135].