Alpha 1-antitrypsin deficiency (
a1-antitrypsin deficiency,
A1AD) is a
genetic disorder that causes defective production of
alpha 1-antitrypsin (A1AT), leading to decreased A1AT activity in the
blood and
lungs, and deposition of excessive abnormal A1AT
protein in
liver cells. There are several forms and degrees of deficiency; the form and degree depend on whether the sufferer has one or two copies of the defective
allele because it is a
co-dominant trait. Severe A1AT deficiency causes panacinar
emphysema or
COPD in adult life in many people with the condition (especially if they are exposed to cigarette smoke). The disorder can lead to various liver diseases in a minority of children and adults, and occasionally more unusual problems. It is treated through avoidance of damaging inhalants and, in severe cases, by
intravenous infusions of the A1AT protein or by
transplantation of the
liver or
lungs. It usually produces some degree of
disability and reduces life expectancy.