Autosomal Genome-Wide Linkage Analysis to Identify Loci for Gallbladder Wall Thickness in Mexican Americans

Relationship between gallbladder surgery and ethnic admixture in African American and Hispanic American women

OBJECTIVES

The objective of this study was to investigate whether differences in admixture in African American and Hispanic American adult women are associated with differences in gallbladder surgery.

METHODS

Gallbladder surgery history on entry to the Women's Health Initiative's (WHI) study was used as a dichotomous outcome measure for this study. The proportion of European, sub-Saharan African, and Amerindian (AMI) admixture was estimated for 10,841 African American and 4,620 Hispanic American women in WHI using 92 ancestry informative markers. Logistic regression analyses assessed the relationship between admixture and gallbladder surgery in WHI women (enrollment at ages >50, mean age 61 years) with or without adjusting for multiple covariates, including measures of adiposity, parity, alcohol use, and education.

RESULTS

There was a significant positive association between AMI admixture and the frequency of gallbladder surgery in Hispanic Americans. The odds ratio (OR) and 95% confidence intervals (CIs) for AMI admixture group was OR=2.97, CI=2.01-4.38, P<10(-4). Although there were strong positive associations with parity and adiposity, and negative associations with alcohol consumption and education, accounting for these covariates did not remove the admixture association (OR=2.46, CI=1.62-3.73). In contrast, the effect of African admixture was nearly indistinguishable from that of the European admixture, both of which were protective in the Hispanic American group, and African admixture had a marginal association with decreased gallbladder surgery in the African American group. Measures of adiposity were associated with increased risk for gallbladder surgery and remained significant after accounting for admixture and each of the other covariates. Education level and alcohol use were associated with decreased risk for gallbladder disease. However, after accounting for the other covariates these variably remained significant.

CONCLUSIONS

AMI admixture is strongly associated with gallbladder surgery in women, even after adjustment for selected risk factors for cholelithiasis. Additional studies to ascertain the specific genetic risk factors underlying these associations are warranted.

Genetic polymorphisms of 15 STR loci in the population of the island of Cres (Croatia)

BACKGROUND

The population of the island of Cres presents one of the few persisting Eastern Adriatic isolates and is thereby suitable for human population differentiation analyses.

AIM

The aim of this study was to analyse the genetic structure of the island of Cres with respect to its eight sub-populations and to compare the genetic variation of the island of Cres with other Eastern Adriatic islands and the Croatian mainland.

SUBJECTS AND METHODS

Fifteen AmpFlSTR identifiler loci were analysed in a sample group of 122 unrelated autochthonous individuals from the island of Cres, Croatia.

RESULTS

Analysis of STR polymorphisms revealed genetic homogeneity among sub-populations of the island of Cres and small but significant levels of genetic heterogeneity among geographically distant Eastern Adriatic islands.

CONCLUSION

Despite a considerable degree of genetic homogeneity among the studied Eastern Adriatic islands, small but significant differentiation between distant islands indicates geographic sub-structuring which follows the isolation by distance model. This study is supportive of the notion that STR markers are useful for genetic differentiation between larger and geographically more distant regions.