title: Aggregate blood pressure responses to serial dietary sodium and potassium intervention: defining responses using independent component analysis.
abstract: BACKGROUND
  Hypertension is a complex trait that often co-occurs with other conditions such as obesity and is affected by genetic and environmental factors. Aggregate indices such as principal components among these variables and their responses to environmental interventions may represent novel information that is potentially useful for genetic studies.
  
  
  RESULTS
  In this study of families participating in the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) Study, blood pressure (BP) responses to dietary sodium interventions are explored. Independent component analysis (ICA) was applied to 20 variables indexing obesity and BP measured at baseline and during low sodium, high sodium and high sodium plus potassium dietary intervention periods. A "heat map" protocol that classifies subjects based on risk for hypertension is used to interpret the extracted components. ICA and heat map suggest four components best describe the data: (1) systolic hypertension, (2) general hypertension, (3) response to sodium intervention and (4) obesity. The largest heritabilities are for the systolic (64%) and general hypertension (56%) components. There is a pattern of higher heritability for the component response to intervention (40-42%) as compared to those for the traditional intervention responses computed as delta scores (24%-40%).
  
  
  CONCLUSIONS
  In summary, the present study provides intermediate phenotypes that are heritable. Using these derived components may prove useful in gene discovery applications.
authors.affiliation: Washington University in St. Louis School of Medicine, St. Louis, MO, USA. allison@wubios.wustl.edu.
authors.forename: Gengsheng
authors.initials: G
authors.lastname: Chen
authors.affiliation: Washington University in St. Louis School of Medicine, St. Louis, MO, USA. lfuentes@dom.wustl.edu.
authors.forename: Lisa
authors.initials: L
authors.lastname: de las Fuentes
authors.affiliation: Washington University in St. Louis School of Medicine, St. Louis, MO, USA. gc@wubios.wustl.edu.
authors.forename: Chi C
authors.initials: CC
authors.lastname: Gu
authors.affiliation: Tulane University Health Sciences Center, New Orleans, LA, USA. jhe@tulane.edu.
authors.forename: Jiang
authors.initials: J
authors.lastname: He
authors.affiliation: Chinese Academy of Medical Sciences, Beijing, China. gudongfeng@vip.sina.com.
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Gu
authors.affiliation: Tulane University Health Sciences Center, New Orleans, LA, USA. tkelly@tulane.edu.
authors.forename: Tanika
authors.initials: T
authors.lastname: Kelly
authors.affiliation: University of Texas Health Sciences Center at Houston, Houston, TX, USA. james.e.hixson@uth.tmc.edu.
authors.forename: James
authors.initials: J
authors.lastname: Hixson
authors.affiliation: National Heart, Lung, and Blood Institute, Bethesda, MD, USA. cashell.jaquish@nih.gov.
authors.forename: Cashell
authors.initials: C
authors.lastname: Jacquish
authors.affiliation: Washington University in St. Louis School of Medicine, St. Louis, MO, USA. rao@wubios.wustl.edu.
authors.forename: D C
authors.initials: DC
authors.lastname: Rao
authors.affiliation: Washington University in St. Louis School of Medicine, St. Louis, MO, USA. treva@wubios.wustl.edu.
authors.forename: Treva K
authors.initials: TK
authors.lastname: Rice
mesh_terms: D050154:Adiposity; D000328:Adult; D001794:Blood Pressure; D019587:Dietary Supplements; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011188:Potassium / Q000008:administration & dosage*; D012307:Risk Factors; D012964:Sodium / Q000008:administration & dosage*
chemical_list: D012964:Sodium; D011188:Potassium