Pernicious anaemia causes a deficiency in vitamin B12, an essential water-soluble vitamin found in virtually all meat products and certain algae, such as seaweed. It helps maintain healthy nerve and red blood cells and is required to make DNA, the genetic material in all cells. Symptoms of pernicious anaemia include fatigue, shortness of breath, brittle nails, pins and needles, and cognitive difficulties (brain fog). Symptoms of pernicious anaemia can become debilitating and cause lasting damage if not caught early enough. Pernicious anaemia can be treated by regular vitamin B12 injections.