Epidemiology and molecular genetics of congenital cataracts

Abstract

Congenital cataract is a crystallin severe blinding disease and genetic factors in disease development are important. Crystallin growth is under a combination of genes and their products in time and space to complete the coordination role of the guidance. Congenital cataract-related genes, included crystallin protein gene (CRYAA, CRYAB, CRYBA1/A3, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD, CRYGS), gap junction channel protein gene (GJA1, GJA3, GJA8), membrane protein gene (GJA3, GJA8, MIP, LIM2), cytoskeletal protein gene (BF-SP2), transcription factor genes (HSF4, MAF, PITX3, PAX6), ferritin light chain gene (FTL), fibroblast growth factor (FGF) and so on. Currently, there are about 39 genetic loci isolated to which primary cataracts have been mapped, although the number is constantly increasing and depends to some extent on definition. We summarized the recent advances on epidemiology and genetic locations of congenital cataract in this review.

Keywords: congenital cataract; crystallin protein gene; cytoskeleton protein; ferritin light chain gene; gap junction channel protein gene; growth factor gene; membrane protein gene; transcription factor genes.

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 an the sutures, shown here as vertical lines but seen clinically as anterior and posterior Y structures.

Figure 2. Congenital cataracts

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.