Genetic mutations in HIV are well known and are very likely, considering the presence of two RNA molecules per virus. Either or both RNA molecules can mutate.

These mutations potentially lead to drug resistance or encourage the virus to evade the body's immune response.

Mutations have created three major groups of HIV - M, N, and O.

• M is found in 99% of all the HIV cases in the world.
• N and O are primarily found in West African countries.
• N, though, infects only a very small number of individuals.

The M group has subgroups lettered A to J. Subgroup B predominates in North America.