African-Americans carrying a genetic sickle cell trait face up to a two-fold risk increase for chronic kidney disease, according to a paper published online November 13 in the Journal of the American Medical Association.
Co-authors from the UNC Gillings School of Global Public Health include epidemiology faculty members Drs. Wayne Rosamond, professor, and Nora Franceschini, research assistant professor.
Study findings, which included data from nearly 16,000 people, may reverse current thinking on sickle cell trait (SCT), a condition long considered benign. In practice, SCT may help flag kidney disease earlier, spur research into possible links between SCT and other common diseases, and ultimately improve public health.
Dr. Rakhi Naik, assistant professor of medicine at Johns Hopkins University and the paper’s first author, said she wanted to investigate whether having SCT involves consequences. “It’s generally under-studied,” Dr. Naik said. “There’s conflicting information and scant evidence about the implications of (sickle cell) trait. There have been national pushes for screening in many different contexts but really, not much is known about SCT. As physicians, we don’t know specifically what to do with that screening information.”
People with SCT inherited a sickle cell gene copy from one parent. They usually do not present disease symptoms. In contrast, those who suffer from sickle cell disease received gene copies from both parents. About one in 12 African-Americans has SCT, as do about 300 million people worldwide. Though it is most prevalent in people of African descent, SCT also is found in populations in the Middle East and India, Dr. Naik said.
Dr. James Wilson, University of Mississippi School of Medicine professor of physiology and a co-senior author on the paper, said the findings are scientifically impactful but should not cause public alarm. “The overall message for people with sickle cell trait is that they still are healthy people,” Dr. Wilson said. “They are at a modestly increased risk for chronic kidney disease.” Overall, African-Americans suffer chronic kidney disease at higher rates than do Whites and Asian-Americans. Further research might definitively show whether SCT is at play.
Paper co-first author Dr. Vimal Derebail, assistant professor of nephrology at the UNC-Chapel Hill School of Medicine, said the findings expand on previous preliminary studies of SCT group members had undertaken. “Maybe these findings will help us gain a better understanding of the well-documented racial disparities in kidney disease,” said Dr. Derebail’s colleague and co-senior author, Dr. Abhijit Kshirsagar, UNC assistant professor of nephrology. Both Drs. Derebail and Kshirsagar are members of the UNC Kidney Center.
In addition to Drs. Derebail, Kshirsagar, Rosamond and Franceschini, study co-authors from UNC include Dr. Nigel S. Key, professor of clinical research at UNC Lineberger Comprehensive Cancer Center. Dr. Alex Reiner, member of the Public Health Sciences Division at Fred Hutchinson Cancer Research Center in Seattle and professor of epidemiology at the University of Washington School of Public Health, co-led the project and is co-senior author on the paper. “These findings suggest that sickle cell trait, which is present in about 8 percent of African-Americans, appears to be one factor that contributes to the higher burden of kidney disease among that population,” Dr. Reiner said. “This study highlights the need for additional research into the health consequences of sickle cell trait.” Dr. Reiner said the findings might have implications regarding screening or more closely monitoring kidney function in SCT carriers. “Since screening for the sickle cell mutation is already widely performed in the U.S., these findings present additional public health and policy implications, including the role of genetic counseling, community awareness and education around genetic findings such as sickle cell trait,” he said.