Chronic kidney disease (CKD), characterized by the gradual loss of the kidneys’ filtering ability, currently affects about 10-13% of adults in the United States. Patients suffering from the most severe form of the condition, end-stage renal disease, require dialysis or a kidney transplant to survive.
Rare mutations that cause kidney disease have been identified, but finding common variations that impact susceptibility to CKD has been difficult. Research published in 2009 showed that a variation in the gene that encodes the most common protein in urine could increase risk for CKD. Now new research, published recently in the journal PLoS Genetics, replicates this finding and shows that the variant may act by influencing how the kidneys adapt to age-related risk factors for kidney disease.
The new results, obtained by analyzing DNA from several thousand Icelandic and Dutch individuals, upheld the previous finding that each copy of the more common A version of in the UMOD gene, which encodes the Tamm-Horsfall protein, is associated with about 25% higher odds of CKD.
To further assess the effects of , the researchers turned their attention to measurements of serum creatinine concentration (SCr), an indicator of kidney function. Higher SCr is associated with decreased filtering ability in the kidney. They found that in the Icelandic sample, the variant affects SCr levels in an age-dependent manner. Before age 50, this variant doesn’t have much of an affect. But thereafter each copy of a A is associated with higher SCr every year, especially around age 70. The effect of was intensified in people with hypertension compared to those without a diagnosis of high blood pressure, as well as in those with type 2 diabetes compared to those without.
Based on their results, the researchers speculate that affects the vulnerability of the kidney to damage as a person ages.
“The common diseases happen at the interface between genes and the environment, and this study offers a clear and medically useful example of this dynamic in action. This SNP is now a validated risk factor for kidney disease, but we have also shown it can be even more meaningful if looked at in the context of age and broader health history,” said the study’s senior author, Kari Stefansson, in a press release.