Rare diseases in Tanzania: a National Call for Action to address policy and urgent needs of individuals with rare diseases.

A rare disease is generally defined as a condition which affects about 1 among 2000 people and currently, there are approximately 5000-8000 rare diseases (RDs) affecting over 400 million people world-wide. Although RDs may arise from different causes such as infections and environmental factors, about 80% are caused by genetic abnormalities. In Tanzania, there are no reports of the types of RDs, their incidence, distribution and numbers of individuals affected.