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Patterns of inheritance in hypertrophic cardiomyopathy: assessment by M-mode and two-dimensional echocardiography
Insights
Hypertrophic cardiomyopathy (HC) shows complex inheritance patterns, not fitting simple Mendelian models. Autosomal dominant inheritance is suggested in some families, but a unified genetic transmission is not supported.
Area of Science:
- Cardiology
- Genetics
- Medical Diagnostics
Background:
- Hypertrophic cardiomyopathy (HC) is a complex cardiac condition with an unclear inheritance pattern.
- Understanding the genetic basis of HC is crucial for diagnosis and family screening.
Purpose of the Study:
- To investigate the mode of inheritance of hypertrophic cardiomyopathy (HC) within families.
- To analyze genetic transmission patterns using echocardiographic data.
Main Methods:
- Studied 367 relatives from 70 families with HC using M-mode and 2D echocardiography.
- Performed pedigree analysis to assess patterns of genetic transmission.
- Utilized complex mathematical models to evaluate inheritance patterns.
Main Results:
- Suggested genetic transmission in 56% of families, with 30% showing autosomal dominant patterns.
- Mathematical analysis indicated that inheritance patterns were not consistent with simple autosomal dominant, recessive, or X-linked models.
- Identified a subclinical form of HC in 20% of affected relatives, detectable only by echocardiography.
- Observed distinct differences in HC expression between probands and affected relatives.
Conclusions:
- The genetic transmission of hypertrophic cardiomyopathy (HC) is complex and does not uniformly follow single-gene Mendelian inheritance.
- Autosomal dominant inheritance is a possible mode in a subset of families.
- Echocardiography is vital for detecting subclinical forms and differentiating disease expression within families.
Abstract:
To determine the mode of inheritance of hypertrophic cardiomyopathy (HC), 367 relatives from 70 families with HC were studied by M-mode and 2-dimensional echocardiography (2-D echo). Inspection of individual family pedigrees suggested that HC was genetically transmitted in 39 pedigrees (56%) and probably sporadic in 31 (44%). Of the 39 pedigrees with familial occurrence, 30 had patterns of inheritance that were most consistent with autosomal dominant transmission. A complex mathematical pedigree analysis determined that patterns of genetic transmission observed in the overall study group were not consistent with known models of autosomal dominant, autosomal recessive, or X-linked inheritance and did not support a unified concept of single-gene Mendelian transmission for all families. The proportion of first-degree relatives affected by HC was 22%, with HC most common in fathers of the proband and least common in offspring. About 20% of the affected relatives (10 of 53) appeared to have inherited a "subclinical" form of HC, in which the sole evidence of HC was the morphologic expression detectable only with echocardiography. Probands and affected relatives differed distinctly with regard to the expression of HC. Probands most often showed functional limitation (81%), subaortic obstruction at rest (53%), particularly diffuse distribution of left ventricular hypertrophy (59%) and marked septal thickening (mean 23 mm). In contrast, affected relatives were characterized by absence of functional limitation (72%) and subaortic obstruction (94%), localized and unusual sites of hypertrophy (60%) and only modest septal thickening (mean 17 mm).(ABSTRACT TRUNCATED AT 250 WORDS)