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October 1973

Twin Study on Ocular Pressure Following Topically Applied Dexamethasone: II. Inheritance of Variation in Pressure Response

Author Affiliations

Bethesda, Md
From the Section on Ophthalmic Field and Developmental Research, Office of Biometry and Epidemiology, National Eye Institute (Drs. Schwartz and Reuling and Mrs. Collie) and the Epidemiology Branch, National Heart and Lung Institute (Dr. Feinleib and Mr. Garrison), Bethesda, Md.

Arch Ophthalmol. 1973;90(4):281-286. doi:10.1001/archopht.1973.01000050283006

A twin study was undertaken to reevaluate a widely held monogenic hypothesis relating to the ocular hypertensive steroid response. In the present (part II) analysis, intrapair differences for steroid response among the monozygotic (MZ) and dizygotic (DZ) samples were compared. Responsiveness was treated as both a qualitative and quantitative trait. For the parameter change in pressure, significant differences were never observed between the MZ and DZ samples and heritability index was consistently low. For final pressure, differences between the twin classes showed a mixed pattern of significance; the heritability index was low- to mid-range. Such observations do not support a predominant role of inheritance. It seems evident that a theory of simple monogenic determination can be questioned on the basis of these new findings.