Washington: Researchers said they have
identified gene variants that help explain high rates of renal
disease among African-Americans, who have a four times greater
risk of kidney problems than whites.
According to the study published in the journal Science
yesterday, variants in the APOL1 gene are the culprits, and
likely evolved as a survival mechanism against lethal
parasites in Africa.
Investigators at Beth Israel Deaconess Medical Center
and the Universite Libre de Bruxelles found patients with
focal segmental glomerulosclerosis (FSGS) and hypertension-
attributed end-stage kidney disease (H-ESKD) had variants in
the APOL1 gene that changed the APOL1 protein sequence.
"We found that the APOL1 risk genes for renal disease
occur in more than 30 per cent of African-American
chromosomes," co-senior author Martin Pollak of Harvard
Medical School said in a statement.
"In fact, the increased risk of kidney disease in
individuals who inherited two copies of these variant forms of
APOL1 is reported to be approximately 10-fold."
FSGS is an injury to the kidney`s filtering system and
ESKD indicates a kidney failure so severe the patient needs
dialysis or a kidney transplant.
Kidney problems, which see about half a million US
patients require dialysis treatment to replace their failed
organs, are particularly pronounced among African-Americans.
Using information from the 1000 Genomes Project DNA data
bank, the researchers singled out candidate genetic variants
and tested DNA sample sets for their presence.
They found that the APOL1 variants G1 and G2 were linked
to a greater risk of both FSGS and hypertension-attributed
ESKD in African-Americans.
"G1 and G2 both changed the coding sequence of APOL1,"
explained Pollak. "Further analyses revealed that these very
same genetic variants conferred human immunity against the
parasite responsible for sleeping sickness."
The tsetse fly transmits the African trypanosome
parasite, which causes sleeping sickness. The disease, not
found outside Africa, causes severed nervous system disorders
and can ultimately lead to brain damage, coma or death.