Max Perutz the onset of Huntington disease is related to the number of glutamine repeats as they bind to form what he called a polar zipper. During the early 1950s, while Watson and Crick were determining the structure of deoxyribonucleic acid (DNA), they made use of unpublished X-ray diffraction images taken by Rosalind Franklin, shown at meetings and shared with them by Maurice Wilkins, and of Franklin's preliminary account of her detailed analysis of the X-ray images included in an unpublished 1952 progress report for the King's College laboratory of Sir John Randall. Randall and others eventually criticised the manner in which
Z-DNA as a left-handed double helix with two antiparallel chains that were held together by Watson–Crick base pairs (see X-ray crystallography). It was solved by Andrew Wang, Alexander Rich, and coworkers in 1979 at MIT. The crystallisation of a B- to Z-DNA junction in 2005 provided a better understanding of the potential role Z-DNA plays in cells. Whenever a segment of Z-DNA forms, there must be B–Z junctions at its two ends, interfacing it to the B-form of DNA found in the rest of the genome. In 2007, the RNA version of Z-DNA, Z-RNA, was described as a transformed version of