A gene variant may be driving high rates of unnecessary bone marrow biopsies in Black Americans, researchers say.

The variant is responsible for lower white blood cell levels in some healthy Black people, the investigators said.

“We’ve essentially created this racial health disparity by not fully considering how genetic variation affects white blood cell levels,” said study co-author Dr. Jonathan Mosley, assistant professor of medicine and biomedical informatics at Vanderbilt University Medical Center in Nashville, Tenn. “Our study supports genotyping African Americans before performing a bone marrow biopsy for the indication of isolated low white blood cell counts.”

The researchers analyzed data on 399 Black patients under age 90 who had bone marrow biopsies at three U.S. medical centers between 1998 and 2020.

Of those, 35 (9%) underwent a bone marrow biopsy due to low white blood cell counts. And 34 of those 35 (97%) had the gene variant that causes lower white cell counts. That compared to 67% of patients who had bone marrow biopsies for other reasons.

The biopsies were normal for 97% of patients with the gene variant, compared to 55% of those who had biopsies for other reasons, according to findings published June 28 in the journal JAMA Internal Medicine.

About 63% of Black Americans carry two copies of the gene variant, according to the researchers.

Mosley noted that the definition of a “normal” range for white blood cell count is based largely on averages from people of European ancestry.

“Genetic variation has a large impact on the levels of biomarkers like white blood cell counts, but reference ranges are defined based on population averages without taking genotypes into account,” Moseley said in a hospital news release.

Study co-author Dr. Sara Van Driest, associate professor of pediatrics and medicine, said the genotype that causes lower white blood cells was almost always present in African American individuals who had a bone marrow biopsy solely for a low white blood cell count.

“We hope that in the future, we can do a better job of recognizing these individuals with a benign cause for their low white blood cells counts so that bone marrow biopsies can be avoided,” she added in the release.

More information

The U.S. National Library of Medicine has more on bone marrow biopsy.

SOURCE: Vanderbilt University Medical Center, news release, June 28, 2021

Source: HealthDay