According to a new study, certain continental Africans and African-Americans carry a genomic variant that causes them to be an average of 6 pounds heavier than those without it.

In this study, researchers hoped to zero in on a potential genetic basis for overweight and obesity levels among continental Africans. To this end, the scientists performed a genome-wide association study for body mass index (BMI) in 1,570 West Africans and then replicated the study in independent samples of West Africans and African-Americans.

Subjects with obesity had higher serum levels of semamorphin-4D (SEMA4D) than nonobese individuals, and elevated SEMA4D levels seemed to increase a person’s risk of developing obesity. A particular variant in SEMA4D (r80068415; C allele) was significantly associated with higher BMI. According to the findings, 1% of West Africans, African-Americans and those with African ancestry possess the SEMA4D variant.

“Despite the great influence of lifestyle and culture on the prevalence of obesity, it is well documented that obesity clusters in families, with heritability estimates as high as 60%,” the authors concluded. “This work highlights the importance of conducting genomic studies in diverse populations and identifies a novel locus that may improve our understanding of BMI-related physiology.”

The study appeared in Obesity (2017; doi: 10.1002/oby.21804).