Autoimmune diseases as a group, in other words, where the immune system attacks part of your body, very common as a group. Individually, much rarer, but some are quite common.
So for example, you can have thyroid problems. Overactive, underactive thyroid, that can be an autoimmune problem.
Type one diabetes, starting in childhood, but sometimes in adulthood as well, that’s an autoimmune problem, maybe triggered by a virus.
Rheumatoid arthritis, where the immune system attacks the joints in your hand, and in the rest of your body and can also affect other organs, which tends to come on a bit more, which tends to come on later in life, maybe in your 40s, 50s and 60s.
Multiple sclerosis is an autoimmune problem of the brain where the, if you like, the electrical cable, the insulation on your nerves is attacked by the immune system and causes neurological problems. Those would be amongst the commonest.
In some ethnic groups, systemic lupus erythematosus, SLE, or lupus, is quite common, particularly if you’re from Southeast Asia.
And then there are rarer ones like scleroderma, which can be pretty nasty. Those would be the commonest autoimmune diseases. There are others, but they are much rarer.