A disease that affects fewer than five in 10,000 of the general population is defined as “rare”; however, due to the number of known rare diseases, the total number of individuals affected by rare diseases is relatively high. According to current estimates, in Germany alone, a rare disease directly affects about four million people. It is predicted that, in the majority of cases, the underlying cause is genetic in origin. With rare diseases that manifest in early childhood, it is likely that the cause of disease is related to the inheritance of genomic changes; therefore, performing molecular genetic analysis within these patients is of particular importance.
For physicians, rare diseases are a unique challenge. Often the diagnostic and therapeutic procedures are complex, and clinical routines are rarely standardized. This is particularly important when multiple organ systems are affected, and the expertise of professionals in many disciplines is required. Therefore, a good cooperation between the family physician, disease specialists, and scientific experts is essential for early diagnosis; however, for some patients who are suffering from a rare disease, there are currently no therapies available.