Two large-scale studies supported by the National Institutes of Health have identified two genes that influence the risk of getting multiple sclerosis (MS). These are the first genes conclusively linked to MS in more than 20 years.

The studies involved scanning DNA samples from more than 20,000 MS patients and unaffected people in the United States and Europe. Researchers were looking for single nucleotide polymorphisms (SNPs), which are single-letter variations in a gene's DNA code. The studies demonstrated an association between MS and SNPs in two genes that encode interleukin receptors (proteins that serve as antennae on the surface of immune cells). Each of the SNPs associated with MS appears to increase the risk of developing the disease by 20% to 30%.

The discovery of these genes could shed new light on what causes MS and on potential treatments for the more than 350,000 Americans who have the disease.

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Dietary carbohydrates may be linked to vision loss. According to a report in the July 2007 issue of the American Journal of Clinical Nutrition, the carbohydrates present in a person's diet may influence the risk of age-related macular degeneration (AMD), the most common cause of vision loss in older adults.

Researchers conducted a study of 4,099 participants ranging in age from 55 to 80 years of age. They classified a total of 8,125 eyes into one of five AMD groups based on the severity of the disease and other factors and found that regular consumption of a diet containing carbohydrates that quickly raise blood sugar levels (carbohydrates with a high glycemic index) significantly increased the risk of AMD compared with regular consumption of carbohydrates with a low glycemic index.

The study concluded that a low-glycemic diet could probably have prevented 20% of AMD cases in the individuals studied.