title: Vertebral Artery Diameter and Flow: Nature or Nurture.
abstract: In contrast with the carotid arteries, the vertebral arteries (VAs) show considerable variation in length, caliber, and vessel course. This study investigated whether the variation in diameter and flow characteristics of the VAs might be inherited.
  
  
  
  A total of 172 Italian twins from Padua, Perugia, and Terni (54 monozygotic, 32 dizygotic) recruited from the Italian Twin Registry underwent B-mode and pulsed-wave Doppler ultrasound assessment of their VAs. VA diameters, peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at the level of a horizontal V2 segment. Univariate quantitative genetic modeling was performed.
  
  
  
  Fourteen percent of the sample had VA hypoplasia. Within pair correlation in monozygotic twins was higher than in dizygotics (.552 vs. .229) for VA diameter. Age- and sex-adjusted genetic effect, under the most parsimonious model, accounted for 54.7% (95% CI: 42.2-69.1%) of the variance of VA diameter, and unshared environmental effect for 45.3% (95% CI: 30.9-57.8%). No heritability was found for the PSV of VA, but shared (34.1%; 95% CI: 16.7-53.7%) and unshared (65.9%; 95% CI: 45.9-83.1%) environmental factors determined the variance. EDV of VA is moderately genetically influenced (42.4%; 95% CI: 16.1-64.9%) and also determined by the unshared environment (57.6%; 95% CI: 34.7-83.7%).
  
  
  
  The diameter of the VAs is moderately genetically determined. Different factors influence the PSV and EDV of VAs, which may highlight the complex hemodynamic background of VA flow and help to understand the vertebral flow anomalies found by ultrasound.
authors.affiliation: Department of Radiology, Semmelweis University, Budapest, Hungary.
authors.forename: Adam Domonkos
authors.initials: AD
authors.lastname: Tarnoki
authors.affiliation: Department of Radiology, Semmelweis University, Budapest, Hungary.
authors.forename: Bence
authors.initials: B
authors.lastname: Fejer
authors.affiliation: Department of Radiology, Semmelweis University, Budapest, Hungary.
authors.forename: David Laszlo
authors.initials: DL
authors.lastname: Tarnoki
authors.affiliation: Central European University, Budapest, Hungary.
authors.forename: Levente
authors.initials: L
authors.lastname: Littvay
authors.affiliation: Vascular and Interventional Radiology Unit, Department of Radiological, Oncological and Anatomo-Pathological Sciences, Sapienza University of Rome, Rome, Italy.
authors.forename: Pierleone
authors.initials: P
authors.lastname: Lucatelli
authors.affiliation: Vascular and Interventional Radiology Unit, Department of Radiological, Oncological and Anatomo-Pathological Sciences, Sapienza University of Rome, Rome, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Cirelli
authors.affiliation: Vascular and Interventional Radiology Unit, Department of Radiological, Oncological and Anatomo-Pathological Sciences, Sapienza University of Rome, Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Fanelli
authors.affiliation: Vascular and Interventional Radiology Unit, Department of Radiological, Oncological and Anatomo-Pathological Sciences, Sapienza University of Rome, Rome, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Sacconi
authors.affiliation: Genetic Epidemiology Unit, National Centre of Epidemiology, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Fagnani
authors.affiliation: Genetic Epidemiology Unit, National Centre of Epidemiology, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Medda
authors.affiliation: Department of Neurosciences, University of Padua School of Medicine, Padua, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Farina
authors.affiliation: Department of Neurosciences, University of Padua School of Medicine, Padua, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Meneghetti
authors.affiliation: Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary.
authors.forename: Tamas
authors.initials: T
authors.lastname: Horvath
authors.affiliation: Università di Perugia, Unità di Medicina Interna, Ospedale "S. Maria", Terni, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Pucci
authors.affiliation: Università di Perugia, Unità di Medicina Interna, Ospedale "S. Maria", Terni, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Schillaci
authors.affiliation: Genetic Epidemiology Unit, National Centre of Epidemiology, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Stazi
authors.affiliation: Department of Neurosciences, University of Padua School of Medicine, Padua, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Baracchini
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D014427:Twins; D018608:Ultrasonography, Doppler / Q000379:methods*; D014711:Vertebral Artery / Q000000981:diagnostic imaging* / Q000502:physiology
keywords: Doppler; flow; genetics; hypoplasia; velocity