Targeted next-generation sequencing helps to decipher the genetic and phenotypic heterogeneity of hypertrophic cardiomyopathy.
Hypertrophic cardiomyopathy (HCM) is mainly associated with myosin, heavy chain 7 (MYH7) and myosin binding protein C, cardiac (MYBPC3) mutations. In order to better explain the clinical and genetic heterogeneity in HCM patients, in this study, we implemented a target-next generation sequencing (NGS) assay. An Ion AmpliSeq™ Custom Panel for the enrichment of 19 genes, of which 9 of these did not encode thick/intermediate and thin myofilament (TTm) proteins and, among them, 3 responsible of HCM phenocopy, was created. Ninety-two DNA samples were analyzed by the Ion Personal Genome Machine: 73 DNA samples (training set), previously genotyped in some of the genes by Sanger sequencing, were used to optimize the NGS strategy, whereas 19 DNA samples (discovery set) allowed the evaluation of NGS performance. In the training set, we identified 72 out of 73 expected mutations and 15 additional mutations: the molecular diagnosis was achieved in one patient with a previously wild-type status and the pre-excitation syndrome was explained in another. In the discovery set, we identified 20 mutations, 5 of which were in genes encoding non-TTm proteins, increasing the diagnostic yield by approximately 20%: a single mutation in genes encoding non-TTm proteins was identified in 2 out of 3 borderline HCM patients, whereas co-occuring mutations in genes encoding TTm and galactosidase alpha (GLA) altered proteins were characterized in a male with HCM and multiorgan dysfunction. Our combined targeted NGS-Sanger sequencing-based strategy allowed the molecular diagnosis of HCM with greater efficiency than using the conventional (Sanger) sequencing alone. Mutant alleles encoding non-TTm proteins may aid in the complete understanding of the genetic and phenotypic heterogeneity of HCM: co-occuring mutations of genes encoding TTm and non-TTm proteins could explain the wide variability of the HCM phenotype, whereas mutations in genes encoding only the non-TTm proteins are identifiable in patients with a milder HCM status.
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Massimiliano
M
Cecconi
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Maria I
MI
Parodi
Cardiology Unit, E.O. Ospedali Galliera, Genova, Italy.
Francesco
F
Formisano
Cardiology Unit, E.O. Ospedali Galliera, Genova, Italy.
Paolo
P
Spirito
Cardiology Unit, St. Andrea Hospital, Sapienza University, Rome, Italy.
Camillo
C
Autore
Cardiology Unit, St. Andrea Hospital, Sapienza University, Rome, Italy.
Maria B
MB
Musumeci
Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy.
Stefano
S
Favale
Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy.
Cinzia
C
Forleo
Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola Hospital, University of Bologna, Bologna, Italy.
Claudio
C
Rapezzi
Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola Hospital, University of Bologna, Bologna, Italy.
Elena
E
Biagini
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Sabrina
S
Davì
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Elisabetta
E
Canepa
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Loredana
L
Pennese
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Mauro
M
Castagnetta
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Dario
D
Degiorgio
Laboratory of Human Genetics, E.O. Ospedali Galliera, Genova, Italy.
Domenico A
DA
Coviello
D000293:Adolescent; D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000235:genetics / Q000473:pathology; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000235:genetics* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005091:Exons / Q000235:genetics; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D009210:Myofibrils / Q000378:metabolism; D010641:Phenotype; D013577:Syndrome; D055815:Young Adult