Physicians Zero In on Eye Disease

The so called arRP-I sequencing array will help physicians hone their diagnoses for patients with the blinding disease known as retinitis pigmentosa (RP). "For diseases that are associated with multiple genes, like RP, we now have a new and faster method for identifying the underlying genetic basis. This is also useful in analyzing complex patterns of inheritance and for understanding how causative genes might interact with each other”, says Kellogg scientist Radha Ayyagari, Ph.D..

Among the outward signs and symptoms are loss of peripheral vision, night blindness, and abnormal results from an electroretinogram (ERG), a test that measures the electrical activity and function of the retina. A patient with the autosomal recessive form of the disease (arRP) has inherited one gene from each parent, neither of whom is affected by RP.

Ayyagari's study involved 70 individuals with a clinical diagnosis of arRP. Thirty-five had not been previously screened, and 35 others with known genetic mutations were screened to validate the results.

The arRP-I chip contained sequences, or genetic codes, of 11 genes that carry approximately 180 mutations associated with early-onset retinal degenerations. To date more than 30 genes have been identified for various forms of RP. Ayyagari notes that while the size of the chip currently limits the ability to array all known RP genes, larger platforms are likely to be available soon.

The arRP-I chips produced 97.6 percent of the sequence analyzed with greater than 99 percent accuracy and reproducibility. The material cost of the arRP-I chip was 23 percent less that of current sequencing methods.; Source: University of Michigan Health System