Objective of study: Ligneous conjunctivitis (l.c.) is a rare form of chronic pseudomembranous conjunctivitis that usually starts in early infancy. The disease may be associated with pseudomembranous lesions of other mucous membranes in the mouth, nasopharynx, trachea and female genital tract. Some affected children also present with occlusive hydrocephalus. Recently, one of us (A.M.) diagnosed for the first time severe plasminogen deficiency in three unrelated patients with ligneous conjunctivitis.

Patients and methods: We examined four unrelated Turkish girls who all developed ligneous conjunctivitis during early infancy. Two of them also suffered from occlusive hydrocephalus. Episodes of venous thrombosis were not reported in any member of the affected families. Hemostaseologic (PLG and other hemostasis parameters) and molecular genetic studies (PCR- and SSCP-analysis of the PLG gene) were performed in all patients as well as in their healthy parents and siblings.

Results. Three patients exhibited undetectable plasma PLG antigen concentrations (< 1 mg/dl) and markedly decreased plasma PLG functional activity levels (< 10 percent). One girl showed a PLG functional activity level of 20 percent. Molecular genetic studies in two of the patients studied so far revealed different homozygous mutations in PLG exon 7 (Arg 216→ His; kringle 2) and in exon 15 (Trp597 → Stop, β-chain), respectively. The parents and siblings were heterozygous for these mutations. In addition, in the latter family the father's second allele revealed a distinct mutation in the PLG gene (Trp597 → Cys)(compound heterozygosity). In accordance, his plasma PLG antigen level was only 1.2 mg/dl and his PLG functional activity was only 15 percent.

Conclusions: Homozygous type I PLG deficiency may cause ligneous conjunctivitis. Here we demonstrate distinct homozygous PLG mutations that cause severe type I PLG deficiency in two patients studied so far. In these two girls, l.c. was shown to be inherited in an autosomal recessive manner.