Pernicious Anemia
Pernicious anemia is also an autoimmune disorder in which the body is not able to make enough vitamin B12. The deficiency of vitamin B12 causes lower production of red blood cells in the body. The blood vessels surrounding the hair bulb in a hair follicle needs a proper amount of red blood cells to function appropriately. So, the reduction of red blood cells leads to the impairment of hair follicle’s function.