Genes for macular degeneration.Variations in two genes could account for three-quarters of all cases of age-related macular degeneration Age-related macular degeneration (ARMD) Degeneration of the macula (the central part of the retina where the rods and cones are most dense) that leads to loss of central vision in people over 60. , a new study reports. The disease is the leading cause of blindness in people over 60 and affects more than 50 million people worldwide. It occurs when light-sensing cells malfunction mal·func·tion v. 1. To fail to function. 2. To function improperly. n. 1. Failure to function. 2. Faulty or abnormal functioning. in a part of the retina called the macula and block the central field of vision. Last year, a team led by Columbia University Columbia University, mainly in New York City; founded 1754 as King's College by grant of King George II; first college in New York City, fifth oldest in the United States; one of the eight Ivy League institutions. researcher Rando Allikmets reported that certain forms of a gene for a protein called factor H can increase a person's risk of age-related macular degeneration. Other versions of this gene seem to protect a person from the disease. Factor H shuts off inflammation throughout the body once an infection is eliminated and the immune reaction immune reaction n. The reaction resulting from the recognition and binding of an antigen by its specific antibody or by a previously sensitized lymphocyte. Also called immunoreaction. is no longer needed. However, of the 1,300 elderly people examined in that study, 29 percent had a risky version of the factor H gene but didn't have macular degeneration macular degeneration, eye disorder causing loss of central vision. The affected area, the macula, lies at the back of the retina and is the part that produces the sharpest vision. . That led Allikmets' team to suspect that other genes affecting the inflammation response that factor H regulates also play a part in the disease. After reexamining blood and tissue samples from the previous study, the researchers honed in on a gene for a protein called factor B, which turns on the same pathway that factor H shuts off. Like the factor H gene, the factor B gene appears to have some variants that increase the risk of macular degeneration and others that provide a protective effect. About 74 percent of the study subjects with the disease had risky gene variants for factor H, factor B, or both, the researchers report in an upcoming Nature Genetics genetics, scientific study of the mechanism of heredity. While Gregor Mendel first presented his findings on the statistical laws governing the transmission of certain traits from generation to generation in 1856, it was not until the discovery and detailed study of . --C.B. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion