Combination of Whole Genome Sequencing, Linkage, and Functional Studies Implicates a Missense Mutation in Titin as a Cause of Autosomal Dominant Cardiomyopathy With Features of Left Ventricular Noncompaction.
BACKGROUND
High throughput next-generation sequencing techniques have made whole genome sequencing accessible in clinical practice; however, the abundance of variation in the human genomes makes the identification of a disease-causing mutation on a background of benign rare variants challenging.


RESULTS
Here we combine whole genome sequencing with linkage analysis in a 3-generation family affected by cardiomyopathy with features of autosomal dominant left ventricular noncompaction cardiomyopathy. A missense mutation in the giant protein titin is the only plausible disease-causing variant that segregates with disease among the 7 surviving affected individuals, with interrogation of the entire genome excluding other potential causes. This A178D missense mutation, affecting a conserved residue in the second immunoglobulin-like domain of titin, was introduced in a bacterially expressed recombinant protein fragment and biophysically characterized in comparison to its wild-type counterpart. Multiple experiments, including size exclusion chromatography, small-angle x ray scattering, and circular dichroism spectroscopy suggest partial unfolding and domain destabilization in the presence of the mutation. Moreover, binding experiments in mammalian cells show that the mutation markedly impairs binding to the titin ligand telethonin.


CONCLUSIONS
Here we present genetic and functional evidence implicating the novel A178D missense mutation in titin as the cause of a highly penetrant familial cardiomyopathy with features of left ventricular noncompaction. This expands the spectrum of titin's roles in cardiomyopathies. It furthermore highlights that rare titin missense variants, currently often ignored or left uninterpreted, should be considered to be relevant for cardiomyopathies and can be identified by the approach presented here.
Robert
R
Hastings
Carin P
CP
de Villiers
Charlotte
C
Hooper
Liz
L
Ormondroyd
Alistair
A
Pagnamenta
Stefano
S
Lise
Silvia
S
Salatino
Samantha J L
SJ
Knight
Jenny C
JC
Taylor
Kate L
KL
Thomson
Linda
L
Arnold
Spyros D
SD
Chatziefthimiou
Petr V
PV
Konarev
Matthias
M
Wilmanns
Elisabeth
E
Ehler
Andrea
A
Ghisleni
Mathias
M
Gautel
Edward
E
Blair
Hugh
H
Watkins
Katja
K
Gehmlich
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D019295:Computational Biology; D064211:Connectin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis / Q000379:methods*; D030541:Databases, Genetic; D004452:Echocardiography; D005260:Female; D008040:Genetic Linkage; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D040941:Heredity; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D056830:Isolated Noncompaction of the Ventricular Myocardium / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000378:metabolism; D010375:Pedigree; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D051381:Rats; D018570:Risk Assessment; D012307:Risk Factors; D013329:Structure-Activity Relationship; D014162:Transfection; D055815:Young Adult
D064211:Connectin; D005819:Genetic Markers; C577292:TCAP protein, human; C577285:TTN protein, human
cardiomyopathy; left ventricular noncompaction; missense mutation; telethonin; titin; whole genome sequencing