Extremely low levels of low-density lipoprotein potentially suggestive of familial hypobetalipoproteinemia: A separate phenotype of NAFLD?

Background: Low-density lipoprotein cholesterol (LDL-C) levels below 50 mg/dL may suggest familial hypobetalipoproteinemia, particularly in patients with hepatic steatosis. The prevalence of hypobetalipoproteinemia in cohorts with nonalcoholic fatty liver disease (NAFLD) is not known, and it is not clear whether the severity of liver disease of these patients is different. The objective of this study was to address these questions in a large pediatric NAFLD cohort.

Methods: Retrospective study of children followed at the Steatohepatitis Center of a tertiary care center from August 2010 to October 2017. Patients with secondary causes of hepatic steatosis and those on statins were excluded.

Results: Of the 740 patients included, 58 (8%) had hypobetalipoproteinemia. These patients were younger (P = .04), had a lower body mass index (P < .01) and waist circumference (P = .01), and were less likely to be on metformin (P = .01). In spite of that, serum aminotransferase levels were not different between those with low, normal, and high LDL-C levels. Of the 222 patients who had both lipid and histology data available, the steatosis score was higher in those with low LDL-C compared to those with normal or elevated LDL-C, a result that trended toward significance (P = .06). The severity of inflammation and fibrosis did not differ between the groups. When all patients with hypertriglyceridemia were excluded, steatosis severity was higher in those with low LDL-C (P = .04).

Conclusion: Hypobetalipoproteinemia is common among patients with NAFLD and is associated with similar liver disease severity in spite of a leaner phenotype and a more favorable metabolic profile.