title: Genetic and environmental effects on carotid flow velocities: an international twin study.
abstract: BACKGROUND
  Altered carotid blood flow velocities (CFV) have a complex background but the underlying genetic contribution is still unclear. We sought to evaluate the influence of genetics, shared and unshared environmental components on individual differences of CFV.
  
  
  METHODS
  193 healthy twin pairs, 126 monozygotic (MZ) and 67 dizygotic (DZ) (mean age 53 ± 14 years) recruited in Italy, in the United States and in Hungary underwent bilateral color-coded Doppler flow assessment of the common carotid artery (CCA) and of the internal carotid artery (ICA) in order to assess the peak systolic (PSV) and end diastolic (EDV) velocities. Means of bilateral CFV values were used in the analysis.
  
  
  RESULTS
  Age- and country-adjusted intra-class correlations were higher in monozygotic than in dizygotic pairs for mean PSV of the ICA indicating a heritability of 63%. Unique environmental factors contributed to 37% of ICA PSV. With regards to the mean PSV and EDV of the CCA, and EDV of the ICA, heritability analysis indicated no discernible role for genetic components, while the contributions of shared and unshared environmental factors ranged between 56% and 63%, and between 37% and 44% adjusted for age and country, respectively. Mean ICA/CCA ratio was driven by unique environmental factors (82%) with modest heritability (18%).
  
  
  CONCLUSIONS
  Our study showed that the heritability of ICA PSV and ICA/CCA ratio is moderate, while the findings do not support heritability of other investigated CFV values. Environmental effects account for a moderate to major portion of the variance. These findings support the value of early ultrasound screening as well as the prevention of modifiable environmental factors in case of altered carotid flow velocities.
authors.affiliation: Vascular and Interventional Radiology Unit, Department of Radiology, Oncology and Anatomic Pathology, Policlinico Umberto I, "Sapienza" University of Rome, Viale Regina Elena 324, Rome 00161, Italy. Electronic address: pierleone.lucatelli@gmail.com.
authors.forename: Pierleone
authors.initials: P
authors.lastname: Lucatelli
authors.forename: Adam Domonkos
authors.initials: AD
authors.lastname: Tarnoki
authors.forename: David Laszlo
authors.initials: DL
authors.lastname: Tarnoki
authors.forename: Maria Fabrizia
authors.initials: MF
authors.lastname: Giannoni
authors.forename: Marianna
authors.initials: M
authors.lastname: Gazzetti
authors.forename: Emanuele
authors.initials: E
authors.lastname: Boatta
authors.forename: Chiara
authors.initials: C
authors.lastname: Zini
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Cotichini
authors.forename: Claudio
authors.initials: C
authors.lastname: Baracchini
authors.forename: Giorgio
authors.initials: G
authors.lastname: Meneghetti
authors.forename: Lorenza
authors.initials: L
authors.lastname: Nisticó
authors.forename: Corrado
authors.initials: C
authors.lastname: Fagnani
authors.forename: Kinga
authors.initials: K
authors.lastname: Karlinger
authors.forename: Tamas
authors.initials: T
authors.lastname: Horvath
authors.forename: Andrea Agnes
authors.initials: AA
authors.lastname: Molnar
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Garami
authors.forename: Emanuela
authors.initials: E
authors.lastname: Medda
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Stazi
authors.forename: Viktor
authors.initials: V
authors.lastname: Berczi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Fanelli
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000473:pathology*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D006814:Hungary; D007511:Ischemia / Q000473:pathology; D007558:Italy; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012307:Risk Factors; D020521:Stroke / Q000235:genetics* / Q000473:pathology; D018608:Ultrasonography, Doppler; D014481:United States; D055815:Young Adult
keywords: Atherosclerosis; Carotid velocities; Heritability; Twins