In a study posted on Sunday, a team of researchers reported seven growing lineages of the novel coronavirus, spotted in states across the country. All of them have evolved a mutation in the same genetic letter.

“There’s clearly something going on with this mutation,” said Jeremy Kamil, a virologist at Louisiana State University Health Sciences Center and a co-author of the new study.

It’s unclear whether it makes the variants more contagious. But because the mutation appears in a gene that influences how the virus enters human cells, the scientists are highly suspicious.

“I think there’s a clear signature of an evolutionary benefit,” Dr. Kamil said.