Though family history in patients with HD has been insignificant, a few susceptibility genes, including C5orf42 and KIAA1377, also known as centrosomal protein 126 (CEP 126), were discovered by whole exome sequencing in four Korean patients [12]. HD is unlikely to occur in those who carry a single copy of the causative variation in either gene. This evidence concerns the gene CEP126 and Huntington disease.