Plasminogen (plg) deficiency has been classified as (i)
hypoplasminogenemia or 'true' type I plg deficiency, and (ii)
dysplasminogenemia, also called type II plg deficiency. Both forms, severe
hypoplasminogenemia and
dysplasminogenemia, are not causally linked to
venous thrombosis.
Dysplasminogenemia does not lead to a specific clinical manifestation and probably represents only a polymorphic variation in the general population, mainly in Asian countries. Severe
hypoplasminogenemia is associated with compromised extracellular
fibrin clearance during wound healing, leading to pseudomembraneous (ligneous) lesions on affected mucous membranes (eye, middle ear, mouth, pharynx, duodenum, upper and lower respiratory tract and female genital tract).
Ligneous conjunctivitis is by far the most common clinical manifestation. More than 12% of patients with severe
hypoplasminogenemia exhibit congenital occlusive
hydrocephalus. In milder cases of
ligneous conjunctivitis, topical application of plg-containing
eye drops, fresh frozen plasma,
heparin,
corticosteroids or certain
immunosuppressive agents (such as
azathioprine) may be more or less effective. Oral treatment with
sex hormones was successful in two female patients with
ligneous conjunctivitis. In severe cases with possibly life-threatening multi-organ involvement, true therapeutic options are not available at present. The plg-knockout mouse is a useful tool to study the many different properties of plg in a variety of settings, such as wound healing, tissue repair and tissue remodeling, virulence and invasiveness of certain bacteria in the human host,
tumor growth and dissemination, as well as
arteriosclerosis.