For a number of persons with rare diseases (RDs) a definite diagnosis remains undiscovered with relevant physical, psychological and social consequences. These pathologies are named undiagnosed rare diseases (URDs).
URDs include pathological conditions without a name, diseases with a well characterized and described phenotype (clinical manifestations of the disease), diseases with an unknown molecular basis or due to non-genetic factors.
URDs require other than specialised clinical centres, outstanding molecular investigations, common protocols and dedicated actions at national and international levels; the unmet needs of undiagnosed patients remain a global issue.
Many “Undiagnosed RDs programs” have been gradually developed on the grounds of a well-structured multidisciplinary approach.
The Undiagnosed diseases network international (UDNI) is active since 2014. It was co-founded by two countries (Italy and the United States of America) and many other countries take part to it. The National centre for rare diseases of the Istituto Superiore di Sanità (ISS, the National Institute of Health in Italy) is the Italian representative in this network.
