Question: What are the rarest human genetics

Michael Kimwele answered on 17 Jul 2025:

Some of the rarest human genetic traits include conditions like Harlequin ichthyosis, an extremely rare and severe genetic skin disorder caused by mutations in the ABCA12 gene, and fibrodysplasia ossificans progressiva (FOP), where soft tissues progressively turn into bone due to a mutation in the ACVR1 gene. Another rare trait is chimerism, where a person carries two distinct sets of DNA, often from a twin that was absorbed in the womb. Congenital insensitivity to pain, a condition where individuals cannot feel physical pain, is also very rare and linked to mutations in the SCN9A gene. These and other rare mutations offer valuable insights into genetics and human biology but affect only a tiny fraction of the population.