Cyflwr difrifol a etifeddir yw ffeibrosis systig (CF) pan fo nam genetig yn achosi ysgyfaint a llwybr treuliad person i’w llenwi â mwcws gludiog sy’n arwain at rwystrau niweidiol.  Mae symptomau yn cynnwys peswch parhaol, heintiau sy’n digwydd dro ar ôl tro, diffyg maeth a phroblemau difrifol eraill fel diabetes.  Ar hyn o bryd, nid oes triniaeth i wella o ffeibrosis systig; nod y triniaethau presennol yw rheoli symptomau unigol.
Cystic fibrosis (CF) is a serious inherited condition where a gene defect causes a person’s lungs and digestive system to become clogged with sticky mucus. This leads to damaging blockages. Symptoms include a persistent cough, recurring infections, malnutrition and other serious complications such as diabetes. At present, there is no cure for cystic fibrosis and current treatments aim to manage the individual symptoms.