Diagnosis of Immunoglobulin G4-related disease in a child with ligneous conjunctivitis: a novel mutation in plasminogen gene and plasminogen activator inhibitor-1 polymorphism.

Objectives: Ligneous conjunctivitis (LC) is a chronic conjunctivitis characterized by recurrent, firm, fibrin-rich, woody pseudomembranes on the palpebral conjunctiva. It is an ultrarare autosomal recessive disease associated with congenital plasminogen (PLG) deficiency due to mutations in the PLG gene (6q26). Immunoglobulin G4-related disease (IgG4-RD) is an idiopathic, systemic fibroinflammatory disease characterized by elevated serum IgG4 concentration and tissue infiltration of IgG4-positive plasma cells leading to organ enlargement, fibrosis and damage.

Case report: A 7-year-old girl with LC was hospitalized for recurrent pancreatitis and diagnosed as IgG4-RD. PLG activity level was 15% (normal range 55-145%). Co-segregation analysis indicated that the patient was homozygous for the c. NG_016200.1(NM_000301.5):c.1465 T>C mutation in PLG gene. c. NG_016200.1(NM_000301.5):c.1465 T>C PLG variant was found to be heterozygous by NGS analysis in both parents. She also had plasminogen activator inhibitor - 1 (PAI-1) NG_013213.1(NM_000602.5):c.-816A>G (4G/4G) homozygous polymorphism and a heterozygote NG_001333.2 (NM_002769.5):c.292_293insC mutation in the serine protease 1 (PRSS-1) gene. However, heterozygous PRSS-1NG_001333.2 (NM_002769.5):c.292_293insC variant was found in the mother of the patient. All detected variants are currently considered as a variant of uncertain (or unknown) significance (VUS) according to the American College of Medical Genetics and Genomics (ACMG) classification. Oral steroid, oral azathioprine, topical fresh frozen plasma, topical heparin, topical steroid and topical cyclosporine were given. After 3 years of follow-up, IgG4-RD is under partial remission and no pseudomembranes.

Conclusion: She is the second case had both LC and IgG4-RD. We identified a NG_016200.1(NM_000301.5):c.1465 T>C novel homozygous mutation in PLG gene and a PAI-1 NG_016200.1(NM_000301.5):c.1465 T>C (4G/4G) homozygous polymorphism, which has been reported as a risk factor for thrombotic events.