<unk><unk>  arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body attacks its own cells. Today there are more than 40 human<unk>  classified as either definite or probable<unk><unk> , and they affect 5% to 7% of the population. Almost all<unk><unk>  appear without warning or apparent cause, and most patients suffer from fatigue.
The causes of<unk><unk>  are still obscure: Some are thought to be either examples of or precipitated by<unk>  of affluence. For example, arthritis and obesity are acknowledged to be related, and the World Health Organisation states that arthritis is most common in developed countries. Most<unk><unk>  are probably the result of multiple circumstances, for example, a genetic predisposition triggered by an infection.
Women tend to be affected more often by<unk>  disorders; nearly 79% of<unk> <unk> patients in the USA are women. Also they tend to appear during or shortly after puberty. It is not known why this is the case, although hormone levels have been shown to affect the severity of some<unk><unk>  such as multiple sclerosis .  Other causes may include the presence of fetal cells in the maternal bloodstream.
List of autoimmune diseases
Hepatitis B risk factors
Hepatitis C risk factors
Hepatitis A risk factors
List of genetic disorders
Influenza risk factors
Hepatitis E risk factors
Hepatitis D risk factors