MedGen

Hypertrophic cardiomyopathy (HCM) is typically defined by the presence of unexplained left ventricular hypertrophy (LVH). Such LVH occurs in a non-dilated ventricle in the absence of other cardiac or systemic disease capable of producing the observed magnitude of increased LV wall thickness, such as pressure overload (e.g., long-standing hypertension, aortic stenosis) or storage/infiltrative disorders (e.g., Fabry disease, amyloidosis). The clinical manifestations of HCM range from asymptomatic LVH to progressive heart failure to sudden cardiac death (SCD), and vary from individual to individual even within the same family. Common symptoms include shortness of breath (particularly with exertion), chest pain, palpitations, orthostasis, presyncope, and syncope. Most often the LVH of HCM becomes apparent during adolescence or young adulthood, although it may also develop late in life, in infancy, or in childhood. [from NCBI]

Hereditary ventricular hypertrophy (CMH, HCM, ASH, or IHSS) in early stages produces a presystolic gallop due to an atrial heart sound, and EKG changes of ventricular hypertrophy. Progressive ventricular outflow obstruction may cause palpitation associated with arrhythmia, congestive heart failure, and sudden death. Seidman (2000) reviewed studies of hypertrophic cardiomyopathy in man and mouse. Reviews Walsh et al. (2022) reviewed hypertrophic cardiomyopathy phenotypes associated with variation in genes encoding nonsarcomeric proteins. The authors suggested that these genes likely contribute to polygenic risk scores derived from genomewide association studies that could be used to improve risk assessment in patients and family members, and noted that the diverse functions of the proteins highlight novel disease pathways and therapeutic targets for cardiomyopathies. Genetic Heterogeneity of Hypertrophic Cardiomyopathy Additional forms of hypertrophic cardiomyopathy include CMH2 (115195), caused by mutation in the TNNT2 gene (191045) on chromosome 1q32; CMH3 (115196), caused by mutation in the TPM1 gene (191010) on chromosome 15q22; CMH4 (115197), caused by mutation in the MYBPC3 gene (600958) on chromosome 11p11; CMH6 (600858), caused by mutation in the PRKAG2 gene (602743) on chromosome 7q36; CMH7 (613690), caused by mutation in the TNNI3 gene (191044) on chromosome 19q13; CMH8 (608751), caused by mutation in the MYL3 gene (160790) on chromosome 3p21; CMH9 (613765), caused by mutation in the TTN gene (188840) on chromosome 2q31; CMH10 (608758), caused by mutation in the MYL2 gene (160781) on chromosome 12q24; CMH11 (612098), caused by mutation in the ACTC1 gene (102540) on chromosome 15q14; CMH12 (612124), caused by mutation in the CSRP3 gene (600824) on chromosome 11p15; CMH13 (613243), caused by mutation in the TNNC1 gene (191040) on chromosome 3p21; CMH14 (613251), caused by mutation in the MYH6 gene (160710) on chromosome 14q12; CMH15 (613255), caused by mutation in the VCL gene (193065) on chromosome 10q22; CMH16 (613838), caused by mutation in the MYOZ2 gene (605602) on chromosome 4q26; CMH17 (613873), caused by mutation in the JPH2 gene (605267) on chromosome 20q12; CMH18 (613874), caused by mutation in the PLN gene (172405) on chromosome 6q22; CMH20 (613876), caused by mutation in the NEXN gene (613121) on chromosome 1p31; CMH21 (614676), mapped to chromosome 7p12.1-q21; CMH22 (see 615248), caused by mutation in the MYPN gene (608517) on chromosome 10q21; CMH23 (see 612158), caused by mutation in the ACTN2 gene (102573) on chromosome 1q43; CMH24 (see 601493), caused by mutation in the LDB3 gene (605906) on chromosome 10q23; CMH25 (607487), caused by mutation in the TCAP gene (604488) on chromosome 17q12; CMH26 (617047), caused by mutation in the FLNC gene (102565) on chromosome 7q32; CMH27 (618052), caused by mutation in the ALPK3 gene (617608) on chromosome 15q25; CMH28 (619402), caused by mutation in the FHOD3 gene (609691) on chromosome 18q12; and CMH29 (620236), caused by mutation in the KLHL24 gene (611295) on chromosome 3q27. The CMH5 designation was initially assigned to a CMH family showing genetic heterogeneity. Subsequently, affected individuals were found to carry mutations in the MYH7 (CMH1) and/or MYBPC3 (CMH4) genes. Mutations in the CALR3 gene (611414), previously suggested to cause a form of CMH (Chiu et al., 2007) designated CMH19, were convincingly shown not to be a monogenic cause of cardiomyopathy by Verhagen et al. (2018); see 611414.0001. Hypertrophic cardiomyopathy has also been associated with mutation in the gene encoding cardiac myosin light-peptide kinase (MYLK2; see 606566.0001), which resides on chromosome 20q13.3; the gene encoding caveolin-3 (CAV3; see 601253.0013), which maps to chromosome 3p25; and with mutations in genes encoding mitochondrial tRNAs: see mitochondrial tRNA-glycine (MTTG; 590035) and mitochondrial tRNA-isoleucine (MTTI; 590045). [from OMIM]

Hypertrophic cardiomyopathy with an asymmetrical pattern of hypertrophy, with a predilection for the interventricular septum and myocyte disarray. [from HPO]