This study was undertaken to determine whether there is familial aggregation of hyperemesis gravidarum (HG), making it a disease amenable to genetic study. Cases with severe nausea and vomiting in a singleton pregnancy treated with intravenous hydration and unaffected friend controls completed a survey regarding family history. Sisters of women with HG have a significantly increased risk of having HG themselves (odds ratio, 17.3; P = .005). Cases have a significantly increased risk of having a mother with severe nausea and vomiting; 33% of cases reported an affected mother compared to 7.7% of controls (P < .0001). Cases reported a similar frequency of affected second-degree maternal and paternal relatives (18% maternal lineage, 23% paternal lineage). There is familial aggregation of HG. This study provides strong evidence for a genetic component to HG. Identification of the predisposing gene(s) may determine the cause of this poorly understood disease of pregnancy. Copyright © 2011 Mosby, Inc. All rights reserved.
