title: Flicker-induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects.
abstract: OBJECTIVE
  The complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele.
  
  
  METHODS
  One hundred healthy subjects (aged between 18 and 45 years) were included in this study. Retinal blood flow regulation was tested by assessing retinal vessel calibres in response to stimulation with diffuse flicker light. Retinal vascular flicker responses were determined with a Dynamic Vessel Analyzer (DVA). In addition, genotyping for rs1061170 was performed.
  
  
  RESULTS
  Eighteen subjects were homozygous for the risk allele C, 50 were homozygous for the ancestral allele T, and 31 subjects were heterozygous (CT). One subject had to be excluded from data evaluation, as no genetic analysis could be performed due to technical difficulties. Baseline diameters of retinal arteries (p = 0.39) and veins (p = 0.64) were comparable between the three groups. Flicker-induced vasodilation in both retinal arteries (p = 0.38) and retinal veins (p = 0.62) was also comparable between the three studied groups.
  
  
  CONCLUSIONS
  Our data indicate that homozygous healthy young carriers of the C risk allele at rs1061170 do not show abnormal flicker-induced vasodilation in the retina. This suggests that the high-risk genetic variant of CFH polymorphism does not impact neuro-vascular coupling in healthy subjects.
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Told
authors.forename: Stefan
authors.initials: S
authors.lastname: Palkovits
authors.forename: Agnes
authors.initials: A
authors.lastname: Boltz
authors.forename: Doreen
authors.initials: D
authors.lastname: Schmidl
authors.forename: Katarzyna J
authors.initials: KJ
authors.lastname: Napora
authors.forename: René M
authors.initials: RM
authors.lastname: Werkmeister
authors.forename: Helmuth
authors.initials: H
authors.lastname: Haslacher
authors.forename: Sophie
authors.initials: S
authors.lastname: Frantal
authors.forename: Alina
authors.initials: A
authors.lastname: Popa-Cherecheanu
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhöfer
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D017242:Complement Factor H / Q000235:genetics; D005260:Female; D005425:Flicker Fusion / Q000502:physiology*; D005838:Genotype; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D020641:Polymorphism, Single Nucleotide; D012171:Retinal Vessels / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*; D055815:Young Adult
chemical_list: C493495:CFH protein, human; D017242:Complement Factor H
keywords: Retinal vessel diameter; Y402H polymorphism; dynamic vessel analyzer; eye; flicker light stimulation; retinal circulation; rs1061170; vasodilation; young healthy subjects