Abstract
The genetic causes of the components of cardiovascular disease (CVD) risk factors and their intercorrelation are indeed complex and only partly understood. Keeping this view in mind, the present work was undertaken to estimate the heritability of conventional CVD risk factors using family study method. A total of twenty-four nuclear families inhabiting in Calcutta and adjacent areas was chosen randomly. Up to first degree relatives including father, mother and other sibs of the proband were considered as participants in the study. Anthropometric measures namely height, weight, waist circumference as well as skinfold thickness at biceps, triceps, subscapular and suprailiac were obtained using standard techniques. Body mass index (BMI), percentage of body fat (PBF), fat mass (FM), waist-hip ratio (WHR), sum of four skinfolds (SF4 ), arm muscle circumference (AMC), arm muscle area (AMA), arm fat area (AFA), systolic (SBP) and diastolic blood pressure (DBP) were also considered. To estimate’heritability’ in the study, the mid parent-offspring model was used where’heritability’ (h2 ) was equivalent to regression co-efficient (b). The regression sum of square (RSS) and total sum of square (TSS) ratio was also calculated both for mid parent-offspring and single parent-offspring. This ratio was considered as a measure of’heritability’ in the study with consideration that RSS is the variation due to genetic factor and the TSS is due to genetic and other additive factor. It was observed that the estimated heritability for BMI ranges from 0.69 to 0.31 using mid-parent off spring model while the range using single parent-offspring model was from 0.40 to 0.16. The range of heritability for SBP in mid parent-offspring model was 0.16 to 0.44 and 0.05 to 0.54 for single parent-offspring model. To conclude, it seems reasonable to argue that in the study a moderate to high h2 was evident for body fat level, body composition and blood pressure measures which indicate a moderate to high aggregation of gene(s) in the family.
Highlights
A commonly used measure to quantify the extent to which the familial aggregation of diseases due to genetic factors is the ‘heritability’
The measures of heritability to evaluate the genetic contributions for quantitative traits must be interpreted with great caution
C., USA, it was observed that the maximal heritability for abdominal visceral fat (AVF), before and after adjustment for total fat mass (FM), was 42 and 50%, respectively while for insulin, it was 21%.[10]
Summary
A commonly used measure to quantify the extent to which the familial aggregation of diseases due to genetic factors is the ‘heritability’. Heritability has the intuitive appeal of quantifying genetic effects without necessarily knowing the mode of inheritance of a trait.[1] Heritability is frequently estimated for complex diseases or traits such as type 2 diabetes mellitus (T2DM), coronary heart diseases (CHD), and serum lipid levels, which are phenotypes reflecting the interplay of genetic and environmental factors.[2] The frequent co-occurrence of T2DM, obesity, and other cardiovascular diseases (CVD) risk factors (e.g., dyslipidemia, hypertension, and chronic inflammation etc.) has led to the hypothesis that these conditions arise from a common antecedent – a concept formalized as metabolic syndrome.[3,4]. The observed correlation between insulin resistance and obesity could be caused by causal associations, by common environmental or genetic backgrounds (pleiotropy), or both causation and common etiology. A causal association apparently cannot explain the entire correlation between obesity and insulin resistance.[5,6,7] Alternatively, genetic or environmental
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
