Browsing by Author "Bos, JM"

Now showing 1 - 3 of 3

Open Access
Distinguishing hypertrophic cardiomyopathy-associated mutations from background genetic noise.
(Journal of cardiovascular translational research, 2014-04) Kapplinger, JD; Landstrom, AP; Bos, JM; Salisbury, BA; Callis, TE; Ackerman, MJ
Despite the significant progress that has been made in identifying disease-associated mutations, the utility of the hypertrophic cardiomyopathy (HCM) genetic test is limited by a lack of understanding of the background genetic variation inherent to these sarcomeric genes in seemingly healthy subjects. This study represents the first comprehensive analysis of genetic variation in 427 ostensibly healthy individuals for the HCM genetic test using the "gold standard" Sanger sequencing method validating the background rate identified in the publically available exomes. While mutations are clearly overrepresented in disease, a background rate as high as ∼5 % among healthy individuals prevents diagnostic certainty. To this end, we have identified a number of estimated predictive value-based associations including gene-specific, topology, and conservation methods generating an algorithm aiding in the probabilistic interpretation of an HCM genetic test.
Open Access
Novel junctophilin-2 mutation A405S is associated with basal septal hypertrophy and diastolic dysfunction.
(JACC. Basic to translational science, 2017-02) Quick, AP; Landstrom, AP; Wang, Q; Beavers, DL; Reynolds, JO; Barreto-Torres, G; Tran, V; Showell, J; Philippen, LE; Morris, SA; Skapura, D; Bos, JM; Pedersen, SE; Pautler, RG; Ackerman, MJ; Wehrens, XHT
BACKGROUND:Hypertrophic cardiomyopathy (HCM), defined as asymmetric left ventricular hypertrophy, is a leading cause of cardiac death in the young. Perturbations in calcium (Ca2+) handling proteins have been implicated in the pathogenesis of HCM. JPH2-encoded junctophilin 2 is a major component of the junctional membrane complex, the subcellular microdomain involved in excitation-contraction coupling. We hypothesized that a novel JPH2 mutation identified in patients with HCM is causally linked to HCM, and alters intracellular Ca2+ signaling in a pro-hypertrophic manner. OBJECTIVES:To determine using a transgenic mouse model whether a JPH2 mutation found in a HCM patient is responsible for disease development. METHODS:Genetic interrogation of a large cohort of HCM cases was conducted for all coding exons of JPH2. Pseudo-knock-in (PKI) mice containing a novel JPH2 variant were subjected to echocardiography, cardiac MRI, hemodynamic analysis, and histology. RESULTS:A novel JPH2 mutation, A405S, was identified in a genotype-negative proband with significant basal septal hypertrophy. Although initially underappreciated by traditional echocardiographic imaging, PKI mice with this JPH2 mutation (residue A399S in mice) were found to exhibit similar basal hypertrophy using a newly developed echo imaging plane, and this was confirmed using cardiac MRI. Histological analysis demonstrated cardiomyocyte hypertrophy and disarray consistent with HCM. CONCLUSIONS:Variant A405S is a novel HCM-associated mutation in JPH2 found in a proband negative for mutations in the canonical HCM-associated genes. Studies in the analogous mouse model demonstrated for the first time a causal link between a JPH2 defect and HCM. Moreover, novel imaging approaches identified subvalvular septal hypertrophy, specific findings also reported in the human JPH2 mutation carrier.
Open Access
PLN-encoded phospholamban mutation in a large cohort of hypertrophic cardiomyopathy cases: summary of the literature and implications for genetic testing.
(American heart journal, 2011-01) Landstrom, AP; Adekola, BA; Bos, JM; Ommen, SR; Ackerman, MJ
BACKGROUND:hypertrophic cardiomyopathy (HCM) is a major cause of sudden death in young athletes and one of the most common inherited cardiovascular diseases, affecting 1 in 500 individuals. Often viewed as a disease of the cardiac sarcomere, mutations in genes encoding myofilament proteins are associated with disease pathogenesis. Despite a clinically available genetic test, a significant portion of HCM patients remain genetically unexplained. We sought to determine the spectrum and prevalence of mutations in PLN-encoded phospholamban in a large cohort of HCM cases as a potential cause of mutation-negative HCM. METHODS:comprehensive genetic interrogation of the promoter and coding region of PLN was conducted using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing. RESULTS:one L39X nonsense mutation was identified in 1 of 1,064 HCM proband cases with a family history of HCM, previously found to be negative for the current HCM genetic test panel. This mutation cosegregated with incidence of HCM in a multigenerational family. Compared with similar studies, we identified an overall yield of PLN-HCM mutations of 0.65%, similar to 3 genes that are part of current HCM genetic test panels. We did not observe any PLN coding sequence genetic variation in 600 reference alleles. CONCLUSIONS:overall, mutations in PLN are rare in frequency, yet the small size of the genetic locus may make it amenable to inclusion on HCM gene test panels, especially because the frequency of background genetic variation among otherwise healthy subjects appears negligible. The exact role of mutations in PLN and other calcium-handling proteins in the development of HCM warrants further investigation.