title: Heritability and genome-wide linkage in US and australian twins identify novel genomic regions controlling chromogranin a: implications for secretion and blood pressure.
abstract: BACKGROUND
  Chromogranin A (CHGA) triggers catecholamine secretory granule biogenesis, and its catestatin fragment inhibits catecholamine release. We approached catestatin heritability using twin pairs, coupled with genome-wide linkage, in a series of twin and sibling pairs from 2 continents.
  
  
  RESULTS
  Hypertensive patients had elevated CHGA coupled with reduction in catestatin, suggesting diminished conversion of precursor to catestatin. Heritability for catestatin in twins was 44% to 60%. Six hundred fifteen nuclear families yielded 870 sib pairs for linkage, with significant logarithm of odds peaks on chromosomes 4p, 4q, and 17q. Because acidification of catecholamine secretory vesicles determines CHGA trafficking and processing to catestatin, we genotyped at positional candidate ATP6N1, bracketed by peak linkage markers on chromosome 17q, encoding a subunit of vesicular H(+)-translocating ATPase. The minor allele diminished CHGA secretion and processing to catestatin. The ATP6N1 variant also influenced blood pressure in 1178 individuals with the most extreme blood pressure values in the population. In chromaffin cells, inhibition of H(+)-ATPase diverted CHGA from regulated to constitutive secretory pathways.
  
  
  CONCLUSIONS
  We established heritability of catestatin in twins from 2 continents. Linkage identified 3 regions contributing to catestatin, likely novel determinants of sympathochromaffin exocytosis. At 1 such positional candidate (ATP6N1), variation influenced CHGA secretion and processing to catestatin, confirming the mechanism of a novel trans-QTL for sympathochromaffin activity and blood pressure.
authors.affiliation: Departments of Medicine and Pharmacology and Center for Human Genetics and Genomics, University of California at San Diego School of Medicine, Veterans Affairs San Diego Healthcare System, La Jolla, CA 92093-0838, USA. doconnor@ucsd.edu
authors.forename: Daniel T
authors.initials: DT
authors.lastname: O'Connor
authors.forename: Gu
authors.initials: G
authors.lastname: Zhu
authors.forename: Fangwen
authors.initials: F
authors.lastname: Rao
authors.forename: Laurent
authors.initials: L
authors.lastname: Taupenot
authors.forename: Maple M
authors.initials: MM
authors.lastname: Fung
authors.forename: Madhusudan
authors.initials: M
authors.lastname: Das
authors.forename: Sushil K
authors.initials: SK
authors.lastname: Mahata
authors.forename: Manjula
authors.initials: M
authors.lastname: Mahata
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Kuixing
authors.initials: K
authors.lastname: Zhang
authors.forename: Tiffany A
authors.initials: TA
authors.lastname: Greenwood
authors.forename: Pei-an Betty
authors.initials: PA
authors.lastname: Shih
authors.forename: Myles G
authors.initials: MG
authors.lastname: Cockburn
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ziegler
authors.forename: Mats
authors.initials: M
authors.lastname: Stridsberg
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
authors.forename: John B
authors.initials: JB
authors.lastname: Whitfield
mesh_terms: D000483:Alleles; D001315:Australia; D001794:Blood Pressure / Q000235:genetics; D019439:Chromaffin Cells / Q000201:enzymology / Q000378:metabolism; D053379:Chromogranin A / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D002886:Chromosomes, Human, Pair 17; D004777:Environment; D005089:Exocytosis; D005260:Female; D008040:Genetic Linkage; D014644:Genetic Variation; D015894:Genome, Human; D006801:Humans; D006973:Hypertension / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood / Q000235:genetics*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D019655:Quantitative Trait, Heritable; D035781:Siblings; D014427:Twins / Q000235:genetics*; D014481:United States
chemical_list: D053379:Chromogranin A; D010446:Peptide Fragments; C109084:chromogranin A (344-364); D006180:Proton-Translocating ATPases