Genetic background a risk factor for eye disease related to diabetes
Latinos who have type 2 diabetes have a significantly higher risk of developing severe diabetic retinopathy – the leading cause of blindness in working-age adults in the United States – if they also have many Native American ancestors.
“Our findings present a strong case that the high prevalence of diabetic retinopathy in Latinos is due in part to genes of Native American origin,” said Raymond Gao, associate professor of ophthalmology and visual sciences and corresponding author on a study reported in the journal Investigative Ophthalmology & Visual Science.
Latinos are a diverse group of populations with varying blends of Native American, African and European ancestry.
They are almost twice as likely to be diagnosed with diabetes as non-Hispanic whites. They also have a higher prevalence of diabetic retinopathy, a complication of diabetes that affects blood vessels in the retina.
While lifestyle and diet have been blamed for Latinos’ higher rates of diabetes, Gao and his colleagues wanted to see if genetic ancestry could be a factor in the development of diabetic retinopathy.
The researchers analyzed DNA from participants in the Los Angeles Latino Eye Study, the largest population-based study of ophthalmic diseases in Latinos.
They estimated the proportion of Native American, European and African genetic ancestry for 135 LALES participants who have type 2 diabetes and severe diabetic retinopathy, and of 809 participants who have type 2 diabetes without severe diabetic retinopathy. Based on their analysis, the researchers determined that roughly half the genetic material was of Native American origin for participants with severe diabetic retinopathy, compared to 45 percent for those without severe diabetic retinopathy.
Participants with more than 50 percent Native American genetic ancestry had an 87 percent higher chance of having vision-threatening diabetic retinopathy compared to those with less than 50 percent Native American ancestry.
The association between Native American ancestry and diabetic retinopathy remained significant after the researchers adjusted for other known risk factors.
“Our next steps will be to try to narrow down which genes among those with greater Native American origin might be contributing to boosting the risk for developing severe diabetic retinopathy,” Gao said.