Novel homozygous mutation of plasminogen in ligneous conjunctivitis: a case report and literature review

Background:Ligneous conjunctivitis (LC) is a rare disease characterized by the development of a wood-like pseudomembrane on the tarsal conjunctiva secondary to type I plasminogen deficiency. Here we reported on a Chinese patient with LC in a consanguineous family and performed a literature review of all reported mutations for this disease. Methods: A 13-month-old girl diagnosed with LC and her parents were included in this study. Hematoxylin and eosin staining was used to perform histopathology examination. The plasminogen activity was determined by chromogenic assay. Sanger sequencing was performed to screen the mutation site for the disease. In silico analysis was applied to predict the pathogenesis of the identified mutation. In addition, we reviewed the literatures on PLG mutations of LC. Results: Histopathology examination revealed the infiltration of inflammatory cells on membranous lesions. Plasma plasminogen activity was severely decreased in the patient and moderately decreased in her parents (patient: plasminogen activity, 2.50%; father: plasminogen activity, 41.02%; mother: plasminogen activity, 54.07%). Co-segregation analysis indicated that the patient was homozygous for the c.763 G > A (p.Glu255Lys) mutation in plasminogen gene (PLG). Bioinformatics analysis strongly suggested that the mutation was damaging for the disease. The model analysis indicated the mutation might cause abnormal spatial structure and low stability, thus affecting functional activity. A literature review of the LC mutations indicated a strong genetic heterogeneity of the disease. Conclusions: LC exhibited strong genetic heterogeneity, and our study identified a novel homozygous missense mutation of plasminogen (c.763 G > A, p.Glu255Lys) in one Chinese patient with LC.