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Gene Variant Increases Risk of Kidney Disease in African-Americans



When a person has kidney disease, the kidneys are unable to fully remove waste products and extra water from the blood. A common kidney disease called focal segmental glomerulosclerosis (FSGS), often progresses to end-stage kidney disease and the need for dialysis or a kidney transplant.


According to an article published online in the Journal of the American Society of Nephrology (13 October 2011), African-Americans with two copies of the APOL1 gene have about a 4% lifetime risk of developing FSGS. The APOL1 gene occurs in about 12% of African-Americans. African Americans who develop kidney disease tend to do so at younger ages than other FSGS patients, with 70% diagnosed with FSGS between age 15 and 39, compared to 42% in that age group for people with one or no APOL1 variants.


Possessing two APOL1 variants also raises the risk for African-Americans with HIV of developing HIV-associated nephropathy (HIVAN) – a type of kidney disease that develops in some people with human immunodeficiency virus – to 50% among those not getting anti-viral therapy. Anti-viral therapy appears fairly effective at preventing HIVAN. According to the authors, the much higher risk of kidney disease in patients with HIV suggests that a second hit with a virus or other unknown factor is necessary for kidney injury in people who have two APOL1 variants. This may be why most people with two APOL1 variants do not develop kidney disease.


FSGS patients with two APOL1 variants respond as well to steroid treatments as their counterparts who don’t have the variants, making steroids a viable treatment option. Further, it was found that kidney disease progresses more rapidly in patients with two APOL1 variants, and it has been hypothesized that aggressive therapy may be advisable.


In 2010, working with researchers at Harvard Medical School, the authors found some kidney disease risk is due to variants APOLI, a gene adjacent to MYH9. These variants appear to have evolved about 5,000 years ago in some regions of sub-Saharan Africa to protect against trypanosomal infection, also called African sleeping sickness, a degenerative and potentially fatal disease affecting tens of thousands of people in those regions. People from other continents do not have the APOL1 variants.


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