In the individuals that have clear eyes are easy to evidence that the Iris shows areas of different thicknesses (atrficas areas, alternating with the other thickest ones), beyond what the distribution of the melanina is not uniform forming – therefore, characteristic radical structures that very generate varied standards. Women ' ' normais' ' men produces but three pigments: the responsible ones for the absorption of the blue one, the green and the red. The combination of the light absorbed for these three pigments, called generically opsinas, makes possible the vision colored in human beings. The genes that bring prescriptions to manufacture the red and green opsinas are lodged in chromosome X, that it characterizes the feminine sex, when occur in duplicates (the masculine sex is defined when the other chromosome) the Y. normal Women have two copies of both the genes. Some mutations exist that allow the red opsina absorb color in the band of the red-orange, some women have as much one alelo modified red-orange. In the formation of the Iris they participate to seven pairs of genes (eyes), but the deafness and the deficiency of pigmentao are related. The cause is chromosomic not-disjunction was suggested in 1932, for Waardenburg, Lyune and collaborators had demonstrated that he was about a chromosomic abnormality identifying the extra presence of chromosomes in the affected ones.

Known level deeper mosaicismo. In 1960, the first cases of translocao for Polani and collaborators had been described and in 1961, the first case of mosaicismo. The mosaicismo is defined as the one presence fabric of at least two ancestries that if they differentiate genetically, but is derived from an only zygote. It is a clinically important riot in the chromosomic riots as of Syndrome of Down. In more general way, the mutations that appear in only cells in the prenatal life or after-Christmas can originate clones of genetically different cells of the original zygote.