title: The heritability of glaucoma-related traits corneal hysteresis, central corneal thickness, intraocular pressure, and choroidal blood flow pulsatility.
abstract: OBJECTIVE
  The purpose of this work was to investigate the heritability of potential glaucoma endophenotypes. We estimated for the first time the heritability of the pulsatility of choroidal blood flow. We also sought to confirm the heritability of corneal hysteresis, central corneal thickness, and 3 ways of measuring intraocular pressure.
  
  
  METHODS
  Measurements were performed on 96 first-degree relatives recruited from Maisonneuve-Rosemont Hospital in Montreal. Corneal hysteresis was determined using the Reichert Ocular Response Analyser. Central corneal thickness was measured with an ultrasound pachymeter. Three measures of intraocular pressure were obtained: Goldmann-correlated and corneal compensated intraocular pressure using the Ocular Response Analyser, and Pascal intraocular pressure using the Pascal Dynamic Contour Tonometer. The pulsatility of choroidal blood velocity and flow were measured in the sub-foveolar choroid using single-point laser Doppler flowmetry (Oculix). We estimated heritability using maximum-likelihood variance components methods implemented in the SOLAR software.
  
  
  RESULTS
  No significant heritability was detected for the pulsatility of choroidal blood flow or velocity. The Goldman-correlated, corneal compensated, and Pascal measures of intraocular pressure measures were all significantly heritable at 0.94, 0.79, and 0.53 after age and sex adjustment (p = 0.0003, p = 0.0023, p = 0.0239). Central corneal thickness was significantly heritable at 0.68 (p = 0.0078). Corneal hysteresis was highly heritable but the estimate was at the upper boundary of 1.00 preventing us from giving a precise estimate.
  
  
  CONCLUSIONS
  Corneal hysteresis, central corneal thickness, and intraocular pressure are all heritable and may be suitable as glaucoma endophenotypes. The pulsatility of choroidal blood flow and blood velocity were not significantly heritable in this sample.
authors: Maisonneuve-Rosemont Hospital Research Center, Montreal, Quebec, Canada. eefreeman@gmail.com
authors: Ellen E
authors: EE
authors: Freeman
authors: Marie-Hélène
authors: MH
authors: Roy-Gagnon
authors: Denise
authors: D
authors: Descovich
authors: Hugues
authors: H
authors: Massé
authors: Mark R
authors: MR
authors: Lesk
mesh_terms: D000328:Adult; D000368:Aged; D002829:Choroid / Q000098:blood supply*; D003315:Cornea / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005901:Glaucoma / Q000235:genetics* / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011673:Pulsatile Flow; D019655:Quantitative Trait, Heritable
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