The eMERGE Network is a consortium of seven adult and two pediatric US cohorts with DNA biorepositories linked to electronic-medical-record data for large-scale, high-throughput genetic research.18–20 Participating sites for the adult cohort included the following: (1) Group Health Cooperative and University of Washington, Seattle, WA; (2) Marshfield Clinic, Marshfield, WI; (3) Mayo Clinic, Rochester, MN; (4) Northwestern University, Evanston, IL; (5) Vanderbilt University, Nashville, TN; (6) Icahn School of Medicine at Mount Sinai, New York, NY; and (7) Geisinger Health System, Danville, PA.20 Northwestern’s cohort included participants ascertained from a liver clinic; these participants were excluded from the calculation of HH penetrance. The Geisinger cohort included participants from a weight-loss and gastric-bypass clinic, which included liver biopsy in its routine care. These individuals were excluded from the calculation of the rate of liver biopsy. Because MAFs for rs1800562 and rs1799945 are more common in individuals of European ancestry and HH is most common in this ancestry, we limited our analysis to this population. The human-subjects procedures that we followed were in accordance with the ethical standards of the responsible committee on human experimentation at each institution, and proper informed consent was obtained from each participant.