Correlates and Heritability of Nonalcoholic Fatty Liver Disease in a Minority Cohort

Abstract

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and insulin resistance. The condition disproportionately affects Hispanic Americans. The aims of this study were to examine the risk factors and heritability of NAFLD in 795 Hispanic American and 347 African‐American adults participating in the Insulin Resistance Atherosclerosis Study (IRAS) Family Study. Computed tomography (CT) scans of the abdomen were evaluated centrally for measures of liver–spleen (LS) density ratio and abdominal fat distribution. Other measures included insulin sensitivity (SI) calculated from a frequently sampled intravenous glucose tolerance test and various laboratory measures. Statistical models which adjust for familial relationships were estimated separately for the two ethnic groups. Heritability was calculated using a variance components approach. The mean age of the cohort was 49 years (range 22–84); 66% were female. NAFLD (LS ratio <1) was more common in Hispanic Americans (24%) than African Americans (10%). NAFLD was independently associated with SI and visceral adipose tissue (VAT) area in both ethnic groups, although the proportion of explained variance was considerably higher in the Hispanic models. Adiponectin contributed significantly in the African‐American models whereas triglycerides (TGs) and plasminogen activator inhibitor 1 (PAI‐1) contributed only in the Hispanic models. Liver density was modestly heritable in both ethnic groups (h2 ∼0.35). In summary, the prevalence of NAFLD was twofold greater in Hispanic than African Americans. Certain correlates of NAFLD were similar between the ethnic groups, whereas others were distinct. NAFLD was modestly heritable. These findings suggest that NAFLD may have a differing environmental and/or genetic basis in these ethnic groups.

The diagnosis and management of non-alcoholic fatty liver disease: Practice Guideline by the American Association for the Study of Liver Diseases, American College of Gastroenterology, and the American Gastroenterological Association

“…32 Compared to non-Hispanic whites, Hispanic individuals have significantly higher and non-Hispanic blacks have significantly lower prevalence of NAFLD. 15,[33][34][35] The prevalence of NAFLD in American-Indian and Alaskan-Native populations appears lower, ranging from 0.6% to 2.2%, although the lack of histologic definition makes it likely that is an underestimate. 36,37 There are data to suggest that hypothyroidism, hypopituitarism, hypogonadism, sleep apnea, and polycystic ovary syndrome independent of obesity are important risk factors for the presence of NAFLD (Table 4).…”

Genetic determinants of hepatic steatosis in man

“…Although the prevalence of diabetes was similar in both groups (17%), metabolic syndrome was more common in Hispanics than African Americans (33% versus 19%), as was NAFLD (24% versus 10%). Liver density as determined by computed tomography scans was modestly heritable in both groups, estimated as 0.35 in Hispanics and 0.32 in African Americans ( 45 ).…”

“…In view of the disproportionate incidence of NAFLD in Hispanics, Wagenknecht et al studied risk factors and heritability of NAFLD in the IRAS Family Study cohort, which included 795 Hispanic-American and 347 AfricanAmerican adults from large families recruited based on family size ( 45 ). The mean age of the cohort was 49 years, and 63% were female.…”

Epidemiology and Natural History of Non-alcoholic Fatty Liver Disease

“…7 Wagenknecht et al have reported that other markers for NAFLD are similar across ethnic groups and yet Hispanics do have the highest prevalence of NAFLD, hepatic steatosis, and elevated aminotransferase levels, followed by whites with the lowest rates in blacks. 29 Yet, at the same time, other markers such as triglycerides (TGs) and age are only associated with NAFLD in Hispanics. 29 It is possible that these apparent ethnic and familial differences are representative of an underlying genetic susceptibility.…”

“…29 Yet, at the same time, other markers such as triglycerides (TGs) and age are only associated with NAFLD in Hispanics. 29 It is possible that these apparent ethnic and familial differences are representative of an underlying genetic susceptibility. There are reports of familial clusters of NAFLD.…”