[Understanding the diagnostic delay in rare diseases].

According to the European definition, rare diseases are life-threatening or chronically debilitating conditions that affect only 5 out of 10,000 people in the European Union. It is estimated that there are around 6000-8000 different rare diseases, affecting 6-8% of the population in the course of their lives. For the Netherlands, this means that about 1 million people are affected by a rare disease, or one in 17 people. Patients with rare diseases indicate that they often have a long and uncertain diagnostic journey behind them, while the first symptoms present in childhood in 75% of the rare diseases. In this perspective, we discuss some of the results from the research report 'Scherperzicht op diagnostischevertragingbijzeldzameaandoeningen' in which the diagnostic journey for patients with rare diseases is mapped out with figures. We also make recommendations to speed up the diagnostic process for patients with rare diseases.