@article {713, title = {Recurrent TTN metatranscript-only c.39974-11T>G splice variant associated with autosomal recessive arthrogryposis multiplex congenita and myopathy.}, journal = {Hum Mutat}, volume = {41}, year = {2020}, month = {2020 02}, pages = {403-411}, 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{\textquoteright} 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.

}, issn = {1098-1004}, doi = {10.1002/humu.23938}, author = {Bryen, Samantha J and Ewans, Lisa J and Pinner, Jason and MacLennan, Suzanna C and Donkervoort, Sandra and Castro, Diana and Topf, Ana and O{\textquoteright}Grady, Gina and Cummings, Beryl and Chao, Katherine R and Weisburd, Ben and Francioli, Laurent and Faiz, Fathimath and Bournazos, Adam M and Hu, Ying and Grosmann, Carla and Malicki, Denise M and Doyle, Helen and Witting, Nanna and Vissing, John and Claeys, Kristl G and Urankar, Kathryn and Beleza-Meireles, Ana and Baptista, Julia and Ellard, Sian and Savarese, Marco and Johari, Mridul and Vihola, Anna and Udd, Bjarne and Majumdar, Anirban and Straub, Volker and B{\"o}nnemann, Carsten G and MacArthur, Daniel G and Davis, Mark R and Cooper, Sandra T} } @article {648, title = {Clinical, genetic, and pathologic characterization of Mexican founder mutation c.1387A>G.}, journal = {Neurol Genet}, volume = {5}, year = {2019}, month = {2019 Apr}, pages = {e315}, abstract = {

Objective: To characterize the clinical phenotype, genetic origin, and muscle pathology of patients with the c.1387A>G mutation.

Methods: Standardized clinical data were collected for all patients known to the authors with c.1387A>G mutations in . Muscle biopsies were reviewed and used for histopathology, immunostaining, Western blotting, and DNA extraction. Genetic analysis was performed on extracted DNA.

Results: We report the clinical phenotypes of 6 patients homozygous for the c.1387A>G mutation in . Onset of symptoms was <2 years, and 5 of the 6 patients never learned to walk. Brain MRIs were normal. Cognition was normal to mildly impaired. Microarray analysis of 5 homozygous c.1387A>G patients revealed a 500-kb region of shared homozygosity at 19q13.32, including . All 4 muscle biopsies available for review showed end-stage dystrophic pathology, near absence of glycosylated α-dystroglycan (α-DG) by immunofluorescence, and reduced molecular weight of α-DG compared with controls and patients with homozygous c.826C>A limb-girdle muscular dystrophy.

Conclusions: The clinical features and muscle pathology in these newly reported patients homozygous for c.1387A>G confirm that this mutation causes congenital muscular dystrophy. The clinical severity might be explained by the greater reduction in α-DG glycosylation compared with that seen with the c.826C>A mutation. The shared region of homozygosity at 19q13.32 indicates that c.1387A>G is a founder mutation with an estimated age of 60 generations (\~{}1,200-1,500 years).

}, issn = {2376-7839}, doi = {10.1212/NXG.0000000000000315}, author = {Lee, Angela J and Jones, Karra A and Butterfield, Russell J and Cox, Mary O and Konersman, Chamindra G and Grosmann, Carla and Abdenur, Jose E and Boyer, Monica and Beson, Brent and Wang, Ching and Dowling, James J and Gibbons, Melissa A and Ballard, Alison and Janas, Joanne S and Leshner, Robert T and Donkervoort, Sandra and B{\"o}nnemann, Carsten G and Malicki, Denise M and Weiss, Robert B and Moore, Steven A and Mathews, Katherine D} }