Congenital cataracts and their molecular genetics

Abstract

Cataract can be defined as any opacity of the crystalline lens. Congenital cataract is particularly serious because it has the potential for inhibiting visual development, resulting in permanent blindness. Inherited cataracts represent a major contribution to congenital cataracts, especially in developed countries. While cataract represents a common end stage of mutations in a potentially large number of genes acting through varied mechanisms in practice most inherited cataracts have been associated with a subgroup of genes encoding proteins of particular importance for the maintenance of lens transparency and homeostasis. The increasing availability of more detailed information about these proteins and their functions and is making it possible to understand the pathophysiology of cataracts and the biology of the lens in general.

Figure 1

Structure of the mature human lens. Cell division occurs in the 10 and 2 O'clock positions of the anterior epithelia, and cells move laterally until they invert in the bow region of the lens and begin loosing their organelles to form cortical fiber cells. Nuclear fiber cells are laid down relatively early in development. The ends of the more peripheral fiber cells meet atn the sutures, shown here as vertical lines but seen clinically as anterior and posterior Y structures.

Fig. 2

A. Slit lamp view of a dense anterior polar cataract.. B. Reflex view of posterior subcapsular cataract. C. Dense nuclear cataract. D. Punctate nuclear cataract. E. Reflex view of a lamellar pulverulent cataract with a cortical rider in the upper right. F. Sutural cataract with a pulverulent nuclear lamellar component.