African-specific genetic variant for obesity identified

An international team of researchers from the National Human Genome Research Institute (NHGRI) has conducted the first study to look at the genetic causes of obesity in the group most affected—African-Americans.

Obesity is at epidemic levels in America with more than one in three adults considered obese. Similarly, one third of children and adolescents between the ages of 6 and 19 are considered either overweight or obese. Obesity causes a myriad of illnesses, such as diabetes, heart disease, mental and emotional disorders, respiratory ailments, infertility in women, sexual dysfunction in men, orthopedic problems, stroke, and cancer. Illnesses related to obesity take a toll on individual and family health, and put pressure on the dwindling health care system.

Make no mistake about it, obesity is a disease caused primarily by a lack of activity coupled with unhealthy eating habits. Medical conditions such as hypothyroidism, Cushings, and Prader-Willi syndrome can contribute to obesity. Other risk factors for becoming obese exist, such as certain medications, pregnancy, trying to quit smoking, and age for example. Regardless, obese and overweight people take in more calories than they burn. When this is done consistently, the result is added body fat.

The fact that obesity clusters in families made researchers curious about the “genomic underpinnings.” Gene expression is certainly one answer. Another is shared values, eating patterns, and activity levels that can also run in families. Researchers found that a small percentage (1%) of West Africans, African Americans, and others with African ancestry have a genetic variant that increases their risk for obesity. This small percentage belies the “strong genetic component” the researchers suggest.

People with genomic differences in a gene called the semaphorin-4D (SEMA4D) gene were about six pounds heavier than those without the genomic variant, according to the study, which was conducted by NHGRI investigators collaborating with African counterparts. This was the first study on people of African descent, and results were published in the March 13, 2017 issue of the journal Obesity.

"By studying people of West Africa, the ancestral home of most African-Americans, and replicating our results in a large group of African-Americans, we are providing new insights into biological pathways for obesity that have not been previously explored," said Dr. Ayo P. Doumatey, co-primary investigator.

Investigators say they plan to do more research, including on zebrafish, with the hope of identifying other genomic factors involved in obesity to better treat and prevent it. Combatting obesity is no mystery. Families need access to healthy food, motivation and safe places to exercise, and social and professional support to make important behavioral changes that will save their lives. It would not hurt to bring physical education back to the schools (for more reasons than one), and ensure that children get nutrition education and at least one or two healthy meals in schools when none are available at home. Not simple or easy, but an economical plan of behavioral changes can be implemented now to change the course of families and save countless human lives, not to mention the zebrafish.

Remember this: a risk factor or a genetic predisposition is not a forgone conclusion or a death sentence. A gene will only express in certain conditions. A risk factor or genetic profile can be offset with behavioral changes; in this case, changes such as learning to cook healthy meals, increasing physical activity, and making crucial lifestyle changes.

While we wait for a confirmed genetic relationship and development of the drug to treat it, use the proven tools available now that can help you and your family avoid obesity and the known related risks for death and disease.