The "HD gene" (huntingtin) was discovered in 1993. Did this discovery lead to a complete understanding of the cause of HD? Question 2 options: A. yes, because an altered gene sequence is found to present in all HD patients B. yes, because an altered protein sequence is encoded by the gene in all HD patients C. no, because discovery of a contributing gene cannot contribute to knowledge of a disease caused by an altered protein D. no, because the functions of normal and altered Huntingtin proteins are still unclear