Scientists have identified alterations in 10 genes that significantly contribute to nearly 10 per cent of all childhood blindness. Of the 10 genes three were linked to activity of one molecule -- known as actin -- among patients with a disease known as ocular coloboma which causes part of the eye to be missing at birth. Ocular coloboma can cause a distinctive keyhole-shaped pupil as it commonly results in a missing segment in the iris the coloured part of the eye. Coloboma can have profound effects on visual ability but it is very variable and therefore likely to be caused
