The biopharmaceutical companies Alnylam and PTC Therapeutics have joined the Spanish Association of Orphan and Ultra-Orphan Drug Laboratories (AELMHU), the organisation that brings together the main pharmaceutical and biotechnology companies committed to investing in the development of new therapies capable of improving the situation of patients suffering from rare and ultra-rare diseases. With these two new additions, AELMHU now has 17 members representing 35% of the pharmaceutical and biotechnology companies present in Spain with orphan or ultra-orphan medicinal products (OMPs) marketed in our country.