Although liver disease is usually linked to alcohol or drugs, but there are over 100 known forms of liver disease caused by a variety of factors and affecting everyone from children to adults.
The most common are infections such as hepatitis A, B, C, D, E, alcohol related, fatty liver, cirrhosis, cancer and drug damage.
Many diseases of the liver are accompanied by jaundice caused by increased levels of bilirubin in the system. Normally, the liver removes bilirubin from the blood and excretes it through bile.
There are also many pediatric liver diseases including  alpha-1 antitrypsin deficiency, alagille syndrome, biliary atresia and langerhans cell histiocytosis.
Cirrhosis is  may be the only liver-related condition that many people have heard of. Cirrhosis is a condition that results from permanent damage or scarring of the liver. It is the end stage of many different forms of liver disease and is known to cause a number of other health problems, including variceal bleeding, ascites and hepatic encephalopathy.

Many types of liver disease still have unknown causes but the most frequent liver diseases are generally caused by one of the following factors:
Viral Hepatitis:- Caused by viruses, the most common forms world-wide are hepatitis A, B and C. Although hepatitis A and B can be prevented by vaccine, there is no vaccine for hepatitis C. In India, hepatitis C is the leading cause of liver transplants.

Obesity:- The leading cause of liver disease in Indian cities is fatty liver disease linked to obesity.

Alcohol:- When the liver has too much alcohol to handle, normal liver function may be interrupted leading to a chemical imbalance. If the liver is required to detoxify alcohol continuously, liver cells may be destroyed or altered resulting in fat deposits (fatty liver) and more seriously, either inflammation (alcoholic hepatitis) and/or permanent scarring (cirrhosis). Liver cancer can also result from alcohol induced liver disease.
Autoimmune Disorders:- Sometimes a body’s immune system may begin to attack the liver or bile ducts causing inflammation and scarring which leads to a progressive form of liver disease. Examples of liver diseases believed to be caused by the immune system are primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) andautoimmune hepatitis.
Drugs and Toxins:- The liver is responsible for processing most of the chemicals and medications that enter your body – this leaves it vulnerable to acute or chronic liver disease caused by chemicals. In some cases, this is a predictable consequence of overexposure or over-consumption of certain chemicals such as acetaminophen or industrial toxins like polyvinyl chloride or carbon tetrachloride. In other cases, chemicals can cause an unpredictable reaction.
Cancer:- If cancer originates in the liver, it is often caused by hepatitis B, hepatitis C or it can develop in cases of advanced liver disease when cirrhosis is present. Although primary liver cancer is relatively uncommon, many other forms of cancer often metastasize in the liver. Because the liver filters a high volume of blood which may be carrying cancer cells, it is susceptible to developing a form of secondary cancer.
Genetics:- Several forms of liver disease are caused or thought to be caused, by defective genes. These forms of liver disease may be diagnosed in infancy or may not show up until later in life. Examples include hemochromatosis, Wilson disease, alpha 1 antitrypsin deficiency and Glycogen Storage disease.