Pernicious anaemia can lead to crippling and death. Sufferers lack an essential enzyme, normally produced in the stomach, without which they cannot absorb vitamin B12. Early symptoms are those for ordinary anaemia: depression, extreme exhaustion and shortness of breath. As the condition develops, there will be difficulty walking, a sore mouth and tongue, stammering and signs of a confused mental state. Left undiagnosed or untreated, the victim can develop jerking of limbs, degeneration of the spinal cord, paralysis and pyschosis.