Ancestral proportions and admixture dynamics in geographically defined African Americans living in South Carolina.

We analyzed admixture in samples of six different African-American populations from South Carolina: Gullah-speaking Sea Islanders in coastal South Carolina, residents of four counties in the "Low Country" (Berkeley, Charleston, Colleton, and Dorchester), and persons living in the city of Columbia, located in central South Carolina. We used a battery of highly informative autosomal, mtDNA, and Y-chromosome markers. Two of the autosomal markers (FY and AT3) are linked and lie 22 cM apart on chromosome 1.

Admixture and relationships of the population of Jacobina, Bahia, Brazil.

As part of the Cornell-Bahia project on leishmaniasis, the people of Jacobina in the state of Bahia in northeastern Brazil were studied for five genetic polymorphisms: ABO blood groups, hemoglobin variants, PGM1, 6PGD, and adenylate kinase. A maximum likelihood method of calculation of frequency of genes for these traits indicates that the ancestry of the people is 45% African, 43% Portuguese, and 12% Brazilian Indian. This estimate is similar to previous estimates of admixture in the people of northeastern Brazil, except for more African and less Caucasian ancestry.

Ethnicity and human biology.

Stanley Garn's book, Human Races (1965), captured the essence of the new genetic concept of ethnic groups as populations which share the same gene pool, shaped by natural selection. Since then new genetic traits, especially DNA polymorphisms, have been employed to build upon his vision. They have proven useful in the forensic sciences, medicine, and the human biology of adaptation, migration, evolution, and phylogeny.

Hypervariable polymorphism of APO(a) in blacks and whites as reflected by phenotyping.

Genetic polymorphism at the apolipoprotein(a) structural locus was investigated in 203 American blacks using a high-resolution SDS-agarose electrophoresis method followed by immunoblotting, and the gene frequency data were compared with a previously screened American white sample using the same method. Between the two samples, a total of 27 discrete APO(a) allelic isoforms have been documented; of these, 24 were common to both groups. Of the 203 blacks screened, APO(a) immunoreactive isoforms were detected in 201, with a total of 101 distinct phenotypes (67 (33%) single-banded and 134 (67%) double-banded).

Ethnic and genetic differences in susceptibility to osteoporotic fractures.

A plethora of investigations in recent years has demonstrated the occurrence of ethnic differences in bone mineral content, bone density and fracture rates. These findings indicate that genetic determinants exist both for bone development during growth and for bone loss during aging. Twin and parent-offspring studies have corroborated the existence of a hereditary component.