Molecular insights into the mechanism of nonrecurrent F8 structural variants: Full breakpoint characterization and bioinformatics of DNA elements implicated in the upmost severe phenotype in hemophilia A. Issue 4 (16th January 2020)

• Record Type: Journal Article
• Authors: Abelleyro, Miguel Martín; Radic, Claudia Pamela; Marchione, Vanina Daniela; Waisman, Karen; Tetzlaff, Tomas; Neme, Daniela; Rossetti, Liliana Carmen; De Brasi, Carlos Daniel
• Is Part Of: Human mutation. Volume 41:Issue 4(2020)
• Page Start: 825
• Page End: 836
• Publication Date: 2020-01-16
• Subjects: bioinformatics -- F8 -- HEMA -- large deletions -- structural variants; Human chromosome abnormalities -- Periodicals; Mutation (Biology) -- Periodicals; 616.04205
• DOI: 10.1002/humu.23977
• Languages: English
• ISSNs: 1059-7794

Abstract

Abstract: Hemophilia A (HA) provides excellent models to analyze genotype–phenotype relationships and mutational mechanisms. Nh F8 ld's breakpoints were characterized using case‐specific DNA‐tags, direct‐ or inverse‐polymerase chain reaction amplification, and Sanger sequencing. DNA‐break's stimulators ( n = 46), interspersed repeats, non‐B‐DNA, and secondary structures were analyzed around breakpoints versus null hypotheses (E‐values) based on computer simulations and base‐frequency probabilities. Nine of 18 (50%) severe‐HA patients with nh F8 lds developed inhibitors, 1/8 affecting one exon and 8/10 (80%) affecting multi‐exons. Nh F8 lds range: 2–165 kb. Five (45%) nh F8 lds involve F8 ‐extragenic regions including three affecting vicinal genes ( SMIM9 and BRCC3 ) but none shows an extra‐phenotype not related to severe‐HA. The contingency analysis of recombinogenic motifs at nh F8 ld breakpoints indicated a significant involvement of several DNA‐break stimulator elements. Most nh F8 ld's breakpoint junctions showed microhomologies (1–7 bp). Three (27%) nh F8 lds show complexities at the breakpoints: an 8‐bp inverted‐insertion, and the remnant two, inverted‐ and direct‐insertions (46–68 bp) supporting replicative models microhomology‐mediated break‐induced replication/Fork Stalling and Template Switching. The remnant eight (73%) nh F8 lds may support nonhomologous end joining/microhomology‐mediated end joining models. Our study suggests the involvement of the retroposition machinery (e.g., Jurka‐targets, Alu‐elements, long interspersed nuclear elements, long terminal repeats), microhomologies, and secondary structures at breakpoints playing significant roles in the origin of the upmost severe phenotype in HA.