Plasminogen activator inhibitor type 1 deficiency

Plasminogen activator inhibitor type 1 (PAI1) deficiency is a rare bleeding disorder that causes excessive or prolonged bleeding due to blood clots being broken down too early. PAI1 is a protein in the body needed for normal blood clotting. When the body does not have enough functional PAI1, the body's ability keep blood clots intact is impaired. Some people with PAI1 deficiency have some functional PAI1 (partial PAI1 deficiency), while others do not have any (complete PAI1 deficiency). Therefore, the severity of symptoms depends on how much functional PAI1 a person has. People with complete PAI1 deficiency may have symptoms in infancy, while those with partial PAI1 deficiency may not have symptoms until later in life, after an injury or surgery.

Symptoms of PAI1 deficiency include excessive or prolonged bleeding after an injury, or after a medical or dental procedure. The bleeding may be delayed if clots initially form but are broken down too early. Internal bleeding after an injury can be life-threatening, particularly if it occurs around the brain. Other symptoms may include delayed wound healing, nosebleeds that last a long time, easy bruising, bleeding in the joints, and excessive bleeding in females during menstruation, pregnancy or childbirth. Some people with PAI1 deficiency may have scar tissue in the heart (cardiac fibrosis).

PAI1 deficiency is caused by mutations in the SERPINE1 gene and inheritance typically is autosomal recessive. The specific mutations present determine whether a person has complete or partial PAI1 deficiency. In rare cases partial PAI1 deficiency has appeared to be autosomal dominant, but the genetic causes in these cases were not determined. In general, people with one SERPINE1 mutation (carriers) will not develop significant symptoms, if any. A diagnosis of PAI1 deficiency may be made based on evaluation of symptoms, various blood tests, and genetic testing of the SERPINE1 gene.

Treatment for severe bleeding episodes may include intravenous antifibrinolytics (drugs that help the blood clot) and infusion of fresh frozen plasma. Antifibrinolytics may also be used for heavy menstrual bleeding or to prevent bleeding during an invasive procedure or childbirth.