Instituto Valenciano de Microbiología

Masía El Romeral
Ctra. de Bétera a San Antonio Km. 0.3
46117 Bétera (Valencia)
Phone. 96 169 17 02
Fax 96 169 16 37
CIF B-96337217


Plasminogen congenital deficiency ... (Congenital plasminogen deficiency) - Gen PLG.

Congenital deficiency of plasminogen is an alteration that causes tumors inflamed mucous membranes. Normally, development of tumors are activated by infection or injury, but may also occur spontaneously in the absence of known triggers. The tumors may recur after being eliminated. Most often, this alteration affects the sclera and the line of the eyelids. A characteristic feature of this disorder is the ligneous conjunctivitis, in which the accumulation of a protein called fibrin causes conjunctivitis and leads to swollen tumors yellowish, whitish or reddish. Most often, the ligneous conjunctivitis occurs inside eyelids, but however, in about a third of cases, it is developed on the cornea. These tumors can tear the cornea or cause scarring. These corneal problems and obstruction caused by tumors inside the eyelid can cause loss of vision.

People with congenital plasminogen deficiency can also develop woody growths on other mucous membranes, including inside the mouth and gums, nasal mucosa, and in women, the vagina. The tumors in the mucous membranes of the gastrointestinal tract can cause ulcers. The tumors can also develop in the trachea, which may cause obstruction of the airways to be life threatening, especially in children. In a small number of cases, affected individuals are born with impaired drainage of cerebrospinal fluid, causing occlusive hydrocephalus. It is unclear how this feature is associated with other signs and symptoms of congenital plasminogen deficiency.

This process is due to mutations in the PLG gene, located on the long arm of chromosome 6 (6q26). This gene encodes plasminogen, which occurs in the liver. Enzymes called plasminogen activators convert plasminogen to plasmin, which results in fibrin formation. Fibrin is the major protein involved in the formation of blood clots and is important for wound healing, creating the substrate to normal tissue to regrow.

There are more than 50 mutations in the PLG gene causing the disease. Mutations in the gene can decrease the amount of plasminogen produced, function, or both. When mutations affect the concentrations of plasminogen, as well as the activity of the protein, it can be said that affected individuals have congenital deficiency of plasminogen I, which is characterized by development of tumors previously described. People with mutations leading to normal levels of plasminogen with reduced activity are said to have congenital deficiency type plasminogen II or displasminogenemia. Often this form of the disease have no symptoms. A reduction in the functional activity of plasminogen, resulting in an accumulation of fibrin. Excessive fibrin and resulting inflammation, causing inflammatory tissue tumors characteristic of congenital deficiency of plasminogen. It is unclear why the excess fibrin accumulates in the mucous membranes without causing thrombosis. The researchers suggest that other blood enzymes can also break down fibrin, helping to compensate for the reduced levels of plasminogen.  

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.  

Tests in IVAMI: in IVAMI perform detection of mutations associated with congenital deficiency of plasminogen, by complete PCR amplification of exons PLG gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).