The College of Optometrists

 

Abstract:

 

The Family Study of Myopia is a project aiming to discover genetic loci causing susceptibility to high myopia. As part of this investigation, the “heritability” of refractive error and other ocular component values was estimated for a large multi-generational pedigree. Heritability indicates the proportion of the variation of a trait which is due to genetic factors within a specific population. A heritability of 1 suggests that a trait is determined wholly by genetic factors, whilst a heritability of 0 suggests that it is determined by wholly environmental factors.  The higher the heritability value, the more the determination of a trait is due to genetic factors. A heritability of 0.41 (p=9.06 x 10-5, S.E.=0.15) was found for refractive error, a heritability of 1.00 (p=1.84 x 10-4, S.E.=0.22) for mean corneal curvature and a heritability of 0.30 (p=0.13, S.E.=0.33) for axial length. This high heritability of ocular refraction suggests the potential for  finding susceptibility loci for the control and development of refractive error. To pinpoint these loci, areas of chromosomes which have previously been suggested to harbour genes controlling refractive error will be investigated for each member of this family to determine whether a particular gene variant is inherited along with the myopia. If this is the case, it will provide convincing evidence for a genetic susceptibility locus for myopia. We are also investigating the involvement of a candidate gene (called Myocilin) by  studying its inheritance in 100 high myopes and their families.