BACKGROUND:

The National Growth and Health Study, NGHS, was an epidemiologic study of 2,379 black and white girls, ages 9-10 years at entry, who were followed annually. The ancillary study had the potential for identifying those genes involved in determining Black/white differences in lipid metabolism and obesity. This was an exciting area in which there was virtually no available information. Finally, the study permitted an examination of the effects of gene variation on changes in quantitative levels of blood lipids as well as in body fat during different stages of pubescence since the NGHS protocol included annual anthropometric and maturation assessments and biannual blood lipid determinations along with extensive environmental measures which included dietary, household, and psychosocial information. The study was unique because of the rare opportunity to do genetic analyses in a large cohort of two ethnic groups of children on whom a very rich data base was available.

DESIGN NARRATIVE:

The study was an independent research project ancillary to the NGHS and utilized the extensive biological and environmental information available from the NGHS core data base. Blood samples were obtained from 1,133 girls seen at their followup examinations in Year 7 in order to determine genotypes at those loci known to be implicated in lipid metabolism and obesity. Both protein [apolipoproteins C-II, D, and E and LP(a)] and DNA [apolipoprotein B, lipoprotein lipase (LPL), and LDL receptor] were analyzed. The distribution of genetic variation within each ethnic group was determined. At each candidate gene locus, the genotype effects were estimated on quantitative level of apolipoproteins and lipoproteins, and also on the degree and distribution of body fat after adjusting for concomitant variables (such as age, biologic maturation stage adiposity) within each ethnic group. By comparing the frequencies of genotypes at candidate loci, their allelic effects were assessed as well as their impact on blood lipids and obesity development in Black and white females.