NOD2 is a gene involved in Crohn's genetic susceptibility. Prognosis is also affected by presentation of genetic mutations. This results in an eventual accumulation of mutations known as genetic load. Risk of developing ovarian cancer in those with genetic factors can be reduced. The genetic and epigenetic changes occur progressively. Anxiety disorders are caused by a complex combination of genetic and environmental factors. Their development is due to both genetic and environmental factors. Another classification scheme considers genetic and demographic factors. Endometriosis is a heritable condition that is influenced by both genetic and environmental factors. Dyslexia is believed to be caused by the interaction of genetic and environmental factors. This results in low morphological and genetic differences. This would lead to inbreeding depression and loss of genetic variability. Spina bifida is believed to be due to a combination of genetic and environmental factors. The above are well-known examples of diseases having both genetic and environmental components. PCOS is due to a combination of genetic and environmental factors.