Alcohol use disorder is a diagnosis made when an individual has severe problems related to drinking alcohol. Alcohol use disorder can cause major health, social, and economic problems, and can endanger affected individuals and others through behaviors prompted by impaired decision-making and lowered inhibitions, such as aggression, unprotected sex, or driving while intoxicated.\n\nAlcohol use disorder is a broad diagnosis that encompasses several commonly used terms describing problems with drinking. It includes alcoholism, also called alcohol addiction, which is a long-lasting (chronic) condition characterized by a powerful, compulsive urge to drink alcohol and the inability to stop drinking after starting. In addition to alcoholism, alcohol use disorder includes alcohol abuse, which involves problem drinking without addiction.\n\nHabitual excessive use of alcohol changes the chemistry of the brain and leads to tolerance, which means that over time the amount of alcohol ingested needs to be increased to achieve the same effect. Long-term excessive use of alcohol may also produce dependence, which means that when people stop drinking, they have physical and psychological symptoms of withdrawal, such as sleep problems, irritability, jumpiness, shakiness, restlessness, headache, nausea, sweating, anxiety, and depression. In severe cases, agitation, fever, seizures, and hallucinations can occur; this pattern of severe withdrawal symptoms is called delirium tremens.\n\nThe heavy drinking that often occurs in alcohol use disorder, and can also occur in short-term episodes called binge drinking, can lead to a life-threatening overdose known as alcohol poisoning. Alcohol poisoning occurs when a large quantity of alcohol consumed over a short time causes problems with breathing, heart rate, body temperature, and the gag reflex. Signs and symptoms can include vomiting, choking, confusion, slow or irregular breathing, pale or blue-tinged skin, seizures, a low body temperature, a toxic buildup of substances called ketones in the blood (alcoholic ketoacidosis), and passing out (unconsciousness). Coma, brain damage, and death can occur if alcohol poisoning is not treated immediately.\n\nChronic heavy alcohol use can also cause long-term problems affecting many organs and systems of the body. These health problems include irreversible liver disease (cirrhosis), inflammation of the pancreas (pancreatitis), brain dysfunction (encephalopathy), nerve damage (neuropathy), high blood pressure (hypertension), stroke, weakening of the heart muscle (cardiomyopathy), irregular heartbeats (arrhythmia), and immune system problems. Long-term overuse of alcohol also increases the risk of certain cancers, including cancers of the mouth, throat, esophagus, liver, and breast. Alcohol use in pregnant women can cause birth defects and fetal alcohol syndrome, which can lead to lifelong physical and behavioral problems in the affected child.

Alcohol use disorder is a diagnosis made when an individual has severe problems related to drinking alcohol. Alcohol use disorder can cause major health, social, and economic problems, and can endanger affected individuals and others through behaviors prompted by impaired decision-making and lowered inhibitions, such as aggression, unprotected sex, or driving while intoxicated.\n\nAlcohol use disorder is a broad diagnosis that encompasses several commonly used terms describing problems with drinking. It includes alcoholism, also called alcohol addiction, which is a long-lasting (chronic) condition characterized by a powerful, compulsive urge to drink alcohol and the inability to stop drinking after starting. In addition to alcoholism, alcohol use disorder includes alcohol abuse, which involves problem drinking without addiction.\n\nHabitual excessive use of alcohol changes the chemistry of the brain and leads to tolerance, which means that over time the amount of alcohol ingested needs to be increased to achieve the same effect. Long-term excessive use of alcohol may also produce dependence, which means that when people stop drinking, they have physical and psychological symptoms of withdrawal, such as sleep problems, irritability, jumpiness, shakiness, restlessness, headache, nausea, sweating, anxiety, and depression. In severe cases, agitation, fever, seizures, and hallucinations can occur; this pattern of severe withdrawal symptoms is called delirium tremens.\n\nThe heavy drinking that often occurs in alcohol use disorder, and can also occur in short-term episodes called binge drinking, can lead to a life-threatening overdose known as alcohol poisoning. Alcohol poisoning occurs when a large quantity of alcohol consumed over a short time causes problems with breathing, heart rate, body temperature, and the gag reflex. Signs and symptoms can include vomiting, choking, confusion, slow or irregular breathing, pale or blue-tinged skin, seizures, a low body temperature, a toxic buildup of substances called ketones in the blood (alcoholic ketoacidosis), and passing out (unconsciousness). Coma, brain damage, and death can occur if alcohol poisoning is not treated immediately.\n\nChronic heavy alcohol use can also cause long-term problems affecting many organs and systems of the body. These health problems include irreversible liver disease (cirrhosis), inflammation of the pancreas (pancreatitis), brain dysfunction (encephalopathy), nerve damage (neuropathy), high blood pressure (hypertension), stroke, weakening of the heart muscle (cardiomyopathy), irregular heartbeats (arrhythmia), and immune system problems. Long-term overuse of alcohol also increases the risk of certain cancers, including cancers of the mouth, throat, esophagus, liver, and breast. Alcohol use in pregnant women can cause birth defects and fetal alcohol syndrome, which can lead to lifelong physical and behavioral problems in the affected child.

De Verneuil et al. (1978) classified porphyria cutanea tarda (PCT), the most common type of porphyria, into 2 types: type I, or 'sporadic' type, associated with approximately 50% level of uroporphyrinogen decarboxylase (UROD; 613521) in liver (Elder et al., 1978; Felsher et al., 1982), and type II, or 'familial' type (176100), characterized by 50% deficient activity of the same enzyme in many tissues (Kushner et al., 1976; Elder et al., 1980). Type I is the most common form of PCT, comprising 70 to 80% of cases. The causes of the deficiency are often unclear and are probably multifactorial (review by Lambrecht et al., 2007).