About 80% of rare diseases have an identified genetic origin and although individually rare, one in 17 people will be affected by a rare disease at some point in their lifetime.
Mae gan tua 80% o glefydau prin darddiad genetig wedi'i nodi, ac er eu bod yn brin yn unigol, bydd un o bob 17 o bobl yn cael eu heffeithio gan glefyd prin ar ryw adeg yn ystod eu hoes.