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Biomedical subjects

I B Borecki

Publications and source records attributed to I B Borecki.

77 records · Page 5Linked to original sources
PubMed1984

A genetic study of hypoalphalipoproteinemia.

Complex segregation analysis under the unified mixed model of inheritance (major gene and multifactorial) is performed on families ascertained through 23 probands with hypoalphalipoproteinemia (depressed HDL-cholesterol, denoted HDL-c). Evidence for segregation of a recessive major gene for depressed HDL-c with frequency q = 0.116, in addition to multifactorial transmission (H = 0.572), is found in these families. Reanalysis of a subset of families with severely depressed HDL-c confirms the conclusions based on the original analysis, except that different definitions of "affection" give rise to different estimates of gene frequency. Our finding of a recessive mode of inheritance differs from previous claims for a dominant gene because previous analyses did not use a mixed model for segregation analysis of hypoalphalipoproteinemia. When the significant multifactorial background is neglected, we also find evidence for the invalid claim of a dominant gene. This demonstrates the necessity of using mixed models for determining the mode of inheritance of a given phenotype.

Cholesterol, HDL↗
PubMedDate not supplied

Population differences in the pattern of familial aggregation for sex hormone-binding globulin and its response to exercise training: the HERITAGE Family Study.

Familial influences were investigated for baseline sex hormone-binding globulin (SHBG) and its response (post-training minus baseline) to a 20-week endurance exercise training program. One hundred, eighty-four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex-by-generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h(2) = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE (h(2) = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size.

Black People↗
PubMedDate not supplied

Evidence of major genes for plasma HDL, LDL cholesterol and triglyceride levels at baseline and in response to 20 weeks of endurance training: the HERITAGE Family Study.

This study assessed major gene effects for baseline HDL-C, LDL-C, TG, and their training responses (post-training minus baseline) in 527 individuals from 99 White families and 326 individuals from 113 Black families in the HERITAGE Family Study. The baseline phenotypes were adjusted for the effects of age and BMI, and the training response phenotypes were adjusted for the effects of age, BMI, and their respective baseline values, within each of the sex-by-generation-by-race groups, prior to genetic analyses. In Whites, we found that LDL-C at baseline and HDL-C training response were under influence of major recessive genes (accounting for 2--30 % of the variance) and multifactorial (polygenic and familial environmental) effects. Interactions of these major genes with sex, age, and BMI were tested, and found to be nonsignificant. In Blacks, we found that baseline HDL-C was influenced by a major dominant gene without a multifactorial component. This major gene effect accounted for 45 % of the variance, and exhibited no significant genotype-specific interactions with age, sex, and BMI. Evidence of major genes for the remaining phenotypes at baseline and in response to endurance training were not found in both races, though some were influenced by major effects that did not follow Mendelian expectations or were with ambiguous transmission from parents to offspring. In summary, major gene effects that influence baseline plasma HDL-C and LDL-C levels as well as changes in HDL-C levels in response to regular exercise were detected in the current study.

Adaptation, Physiological↗
PubMedDate not supplied

Trade-off between sibship size and sampling scheme for detecting quantitative trait loci.

There is general consensus that linkage with a quantitative trait locus cannot be detected with a reasonable number of sibpairs unless that trait has a very high heritability or the pairs are highly selected. However, the latter may require the screening of a very large number of pairs before a relatively small number of highly informative pairs is attained. At the same time, it is known that, for the same number of typed individuals, larger sibships tend to provide more linkage information than do independent sibpairs. We thus compared the efficiency of two sampling schemes, (1) random and (2) single ascertainment via an individual with an extreme phenotype, for sibship sizes ranging from two to five. The results demonstrate the clear trade-off between sibship size and the stringency of the ascertainment scheme.

Genes, Recessive↗