Pedigree analysis of sickle-cell disease Pedigree analysis of sickle-cell disease. The top part of the figure (A) shows the first part of the β-globin gene and the MstII restriction enzyme sites in the normal (A) and sickle-cell (S) β-globin genes. Digestion with the restriction enzyme MstII results in DNA fragments 1.15 kb and 0.2 kb long in normal individuals. The T-to-A change in individuals with sickle-cell disease abolishes one of the three MstII sites around the β-globin gene; hence, a single restriction fragment 1.35 kb in length is generated in response to MstII. This size difference is easily detected on a Southern blot. (B) Pedigree analysis shows three possibilities: AA = normal (open circle); AS = heterozygous (half-solid circles, half-solid square); SS = homozygous (solid square). This approach can allow for prenatal diagnosis of sickle-cell disease (dash-sided square). See the text. Source: Molecular Genetics, Recombinant DNA, & Genomic Technology, Harper's Illustrated Biochemistry, 30e Citation: Rodwell VW, Bender DA, Botham KM, Kennelly PJ, Weil P. Harper's Illustrated Biochemistry, 30e; 2015 Available at: http://accesspharmacy.mhmedical.com/DownloadImage.aspx?image=/data/books/1366/rod_ch39_f009.png&sec=73245579&BookID=1366&ChapterSecID=73245504&imagename= Accessed: December 22, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved