Recurrent TTN metatranscript‐only c.39974–11T>G splice variant associated with autosomal recessive arthrogryposis multiplex congenita and myopathy. Issue 2 (3rd December 2019)

• Record Type: Journal Article
• Authors: Bryen, Samantha J.; Ewans, Lisa J.; Pinner, Jason; MacLennan, Suzanna C.; Donkervoort, Sandra; Castro, Diana; Töpf, Ana; O'Grady, Gina; Cummings, Beryl; Chao, Katherine R.; Weisburd, Ben; Francioli, Laurent; Faiz, Fathimath; Bournazos, Adam M.; Hu, Ying; Grosmann, Carla; Malicki, Denise M.; Doyle, Helen; Witting, Nanna; Vissing, John; Claeys, Kristl G.; Urankar, Kathryn; Beleza‐Meireles, Ana; Baptista, Julia; Ellard, Sian; Savarese, Marco; Johari, Mridul; Vihola, Anna; Udd, Bjarne; Majumdar, Anirban; Straub, Volker; Bönnemann, Carsten G.; MacArthur, Daniel G.; Davis, Mark R.; Cooper, Sandra T.;
• Is Part Of: Human mutation. Volume 41:Issue 2(2020)
• Page Start: 403
• Page End: 411
• Publication Date: 2019-12-03
• Subjects: alternative splicing -- arthrogryposis -- congenital titinopathies -- intronic splice variant -- TTN metatranscript‐only; Human chromosome abnormalities -- Periodicals; Mutation (Biology) -- Periodicals; 616.04205
• DOI: 10.1002/humu.23938
• Languages: English
• ISSNs: 1059-7794

Abstract

Abstract: We present eight families with arthrogryposis multiplex congenita and myopathy bearing a TTN intron 213 extended splice‐site variant (NM_001267550.1:c.39974‐11T>G), inherited in trans with a second pathogenic TTN variant. Muscle‐derived RNA studies of three individuals confirmed mis‐splicing induced by the c.39974‐11T>G variant; in‐frame exon 214 skipping or use of a cryptic 3′ splice‐site effecting a frameshift. Confounding interpretation of pathogenicity is the absence of exons 213‐217 within the described skeletal muscle TTN N2A isoform. However, RNA‐sequencing from 365 adult human gastrocnemius samples revealed that 56% specimens predominantly include exons 213‐217 in TTN transcripts (inclusion rate ≥66%). Further, RNA‐sequencing of five fetal muscle samples confirmed that 4/5 specimens predominantly include exons 213‐217 (fifth sample inclusion rate 57%). Contractures improved significantly with age for four individuals, which may be linked to decreased expression of pathogenic fetal transcripts. Our study extends emerging evidence supporting a vital developmental role for TTN isoforms containing metatranscript‐only exons.