Identification of the candidate source element for a disease-causing Alu insert. The sequence of the disease-causing Alu compared to the candidate source element found on chromosome 14 in the genome. The Alu sequences share 100% identity within the body of the element. (A) Alu insertion disrupting Cftr gene, exon 17b (Chen et al. 2008). Flanking sequence is lower case. Inserted Alu sequence is italicized. Bold text indicates the target site duplication formed during the retrotransposition process. The box outlines the thymine mutation that is inferred to have transferred to the progeny sequence during retrotransposition. Underlined portions within the direct repeat indicate the transcription terminator. (B) The parent locus of the Cftr Alu insertion. With the flanking sequence, Alu, target site duplication, thymine residue, and terminator labeled as in A.
