Ocular findings in triploidy.

The usual chromosome complement of man is 46: 22 pairs of autosomes and two sex chromosomes. Normally, an individu­ al acquires one chromosome of each autosome pair and one sex chromosome from each parent. The anomaly of triploidy refers to that specific defect in which an individual's cells have 69 chromosomes: three of each autosome and three sex chromosomes. Triploidy can result from some mechanism such as fertilization of a diploid ovum, fusion of a polar body with a fertilized ovum, or from double fertili­ zation of a normal ovum by two sperms. Postfertilization generation of triploid cell lines can produce mosaicism. Trip­ loidy is common in spontaneous abor­ tuses, but rare in livebirths. A triploid mosaic individual may survive to adult life; survivors have some cell lines with 46 chromosomes (usually peripheral blood) and other cell lines with 69 chro­ mosomes. We studied ocular abnormalities in a liveborn, 30-week-gestation triploid child, and in two teenage triploid mosaic individuals.