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Biomedical subjects

D C Rao

Publications and source records attributed to D C Rao.

At least 19 recordsLinked to original sources
PubMed1979

Genetic and environmental determinants of periodontal disease.

Reanalysis of data on periodontal disease in 241 families [Chung et al, 1977b], based on an extended and more satisfactory path model [Rao et al, 1979], failed to detect significant heritability, and concluded in favor of cultural inheritance only, without maternal effects or intergenerational differences. The most parsimonious hypothesis yields a relative variance component of 0.338 +/- 0.024 due to indexed environment for both children and adults, the remainder (1.0--0.338 = 0.662) being due to residual nongenetic factors.

Culture↗
PubMed1979

Determinants of plasma uric acid.

Obesity, alcohol consumption, and hematocrit provide an index of plasma uric acid, which in path analysis has a cultural heritability of 0.11 in children and 0.23 in parents, a small maternal effect, and a genetic heritability of 0.25 in both generations. Preliminary evidence for a major locus is destroyed by the omission of one exceptional child. There is no evidence against the polygenic hypothesis for hyperuricemia in the Japanese-American population studied.

Adult↗
PubMed1979

Cultural and biological determinants of lipoprotein concentrations.

A general linear model is presented here for biological and cultural inheritance involving ten parameters to be estimated from 16 correlations in nuclear families, providing ample degrees of freedom to test goodness of fit. Applied to six lipoprotein traits the model fits acceptably to all, although there is evidence of transient maternal effects for cholesterol and lipemia. Genetic heritability in children ranges from 0.175 for triglyceride to 0.562 for total cholesterol. Cultural heritability in children ranges from 0.012 for VLDL to 0.149 for HDL-cholesterol.

Adult↗
PubMed1979

Complex segregation analysis of diabetes mellitus.

Complex segregation analysis was applied to a sample of 12,293 nuclear families each with at least 1 diabetic patient. The families were divided into two groups depending on the proband's treatment: insulin-dependent (IDG) and insulin-independent (IIG). Heterogeneity analysis has revealed a highly significant difference in the IIG group when families were divided into different mating types. The higher recurrence risk was found in the group with affected mothers. Also evidence for a major recessive gene was found in the IGG group, while it was not possible to distinguish between the hypothesis for absence of a major locus and absence of polygenic inheritance in the IDG group. Risks to develop the disease were calculated for a few typical situations.

Adolescent↗
PubMed1979

Joint distribution of z transformations estimated from the same sample.

When correlations are estimated by maximum likelihood method from the same sample, Fisher's z transformations of the correlations (as well as the sample correlations themselves) are shown to be asymptotically distributed as multivariate normal with appropriate mean and dispersion matrix.

Genetics, Population↗
PubMed1979

A maximum likelihood map of chromosome 1.

Thirteen loci are mapped on chromosome 1 from genetic evidence. The maximum likelihood map presented permits confirmation that Scianna (SC) and a fourteenth locus, phenylketonuria (PKU), are on chromosome 1, although the location of the latter on the PGM1-AMY segment is uncertain. Eight other controversial genetic assignments are rejected, providing a practical demonstration of the resolution which maximum likelihood theory brings to mapping.

Chromosome Mapping↗
PubMed1978

A genetic study of immunoglobulin E.

Path analysis gives evidence of genetic heritability (.425) for serum IgE levels. Complex segregation analysis indicates, in addition to significant polygenic heritability, a major regulatory locus RE, with homozygotes re/re maintaining persistently high levels of IgE. The gene frequency of re is .489, and the displacement is 1.67 standard deviations.

Female↗
PubMed1977

Residual family resemblance for PTC taste sensitivity.

Complex segregation analysis reveals no evidence for incomplete dominance, polygenic variation, or an effect of family environment on PTC sensitivity. Estimates of gene frequency and displacement from a phenotypic trichotomy agree closely with conventional values for the the dichotomy of tasters vs. nontasters.

Gene Frequency↗
PubMed1977

Genetic and environmental determinants of skin color.

Skin reflectance measurements on a sample of 154 Black and 191 White same-sex twin pairs, attending Philadelphia area schools, are analyzed to determine the effects of genetic and environmental factors. The measurements obtained in July and August, on the forehead, inner upper arm, and flexor surface of the forearm with red, green, and blue filters, were reduced to one index which we call skin color. Analysis of this index using the path analysis of Rao et al. ('74) estimates the major variance components due to racial, residual genetic, and common environmental factors as 67%, 5%, and 22%, respectively.

Adolescent↗