2. Academic Validation
  3. Genetic Mosaicism in Calmodulinopathy

Genetic Mosaicism in Calmodulinopathy

  • Circ Genom Precis Med. 2019 Sep;12(9):375-385. doi: 10.1161/CIRCGEN.119.002581.
Lisa M Wren 1,  Juan Jiménez-Jáimez 2,  Saleh Al-Ghamdi 3,  Jumana Y Al-Aama 4 5,  Amnah Bdeir 5,  Zuhair N Al-Hassnan 6,  Jyn L Kuan 7,  Roger Y Foo 7,  Franck Potet 1,  Christopher N Johnson 8,  Miriam C Aziz 9,  Gemma L Carvill 9,  Juan-Pablo Kaski 10,  Lia Crotti 11 12 13,  Francesca Perin 14,  Lorenzo Monserrat 13,  Paul W Burridge 1,  Peter J Schwartz 12,  Walter J Chazin 8,  Zahurul A Bhuiyan 15,  Alfred L George Jr 1
Affiliations

Affiliations

  • 1 From the Department of Pharmacology (L.M.W., F.P., P.W.B., A.L.G.), Northwestern University Feinberg School of Medicine, Chicago, IL.
  • 2 Cardiology Department (J.J.-J.), Virgen de las Nieves Hospital, Granada, Spain.
  • 3 Cardiac Sciences Department, Section of Pediatric Cardiology, King Abdulaziz Cardiac Center, Ministry of National Guard Health Affairs, Riyadh (S.A.-G.).
  • 4 Department of Genetic Medicine, Faculty of Medicine (J.Y.A.-A.), King Abdulaziz University, Jeddah.
  • 5 Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders (J.Y.A.-A., A.B.), King Abdulaziz University, Jeddah.
  • 6 The Cardiovascular Genetics Program, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia (Z.N.A.-H.).
  • 7 Department of Cardiology, National University Heart Center and Cardiovascular Research Institute, National University of Singapore (J.L.K., R.Y.F.).
  • 8 Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN (C.N.J., W.J.C.).
  • 9 Department of Neurology (M.C.A., G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL.
  • 10 Institute of Cardiovascular Science, University College London, United Kingdom (J.-P.K.).
  • 11 Department of Medicine and Surgery, University of Milano-Bicocca (L.C.).
  • 12 IRCCS Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Milan, Italy (L.C., P.J.S.).
  • 13 Cardiology Department, Health in Code SL, A Coruña, Spain (L.M.).
  • 14 Pediatric Cardiology Division (F.P.), Virgen de las Nieves Hospital, Granada, Spain.
  • 15 Unité de Recherche Cardiogénétique, Service de Médecine Génétique, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland (Z.A.B.).
PMID: 31454269 DOI: 10.1161/CIRCGEN.119.002581
Abstract

Background: CaM (Calmodulin) mutations are associated with congenital arrhythmia susceptibility (calmodulinopathy) and are most often de novo. In this report, we sought to broaden the genotype-phenotype spectrum of calmodulinopathies with 2 novel Calmodulin mutations and to investigate mosaicism in 2 affected families.

Methods: CaM mutations were identified in 4 independent cases by DNA sequencing. Biochemical and electrophysiological studies were performed to determine functional consequences of each mutation.

Results: Genetic studies identified 2 novel CaM variants (CALM3-E141K in 2 cases; CALM1-E141V) and one previously reported CaM pathogenic variant (CALM3-D130G) among 4 probands with shared clinical features of prolonged QTc interval (range 505-725 ms) and documented ventricular arrhythmia. A fatal outcome occurred for 2 of the cases. The parents of all probands were asymptomatic with normal QTc duration. However, 2 of the families had multiple affected offspring or multiple occurrences of intrauterine fetal demise. The mother from the family with recurrent intrauterine fetal demise exhibited the CALM3-E141K mutant allele in 25% of next-generation sequencing reads indicating somatic mosaicism, whereas CALM3-D130G was present in 6% of captured molecules of the paternal DNA sample, also indicating mosaicism. Two novel mutations (E141K and E141V) impaired Ca2+ binding affinity to the C-domain of CaM. Human-induced pluripotent stem cell-derived cardiomyocytes overexpressing mutant or wild-type CaM showed that both mutants impaired Ca2+-dependent inactivation of L-type Ca2+ channels and prolonged action potential duration.

Conclusions: We report 2 families with somatic mosaicism associated with arrhythmogenic calmodulinopathy, and demonstrate dysregulation of L-type Ca2+ channels by 2 novel CaM mutations affecting the same residue. Parental mosaicism should be suspected in families with unexplained fetal arrhythmia or fetal demise combined with a documented CaM mutation.

Keywords

arrhythmia; calmodulin; genotype; long QT syndrome; mosaicism.

Figures