Background: Waardenburg syndrome is an autosomal dominant disorder with varying degrees of sensorineural hearing loss as well as abnormal pigmentation in hair, skin, and iris. There are four types of Waardenburg syndrome (1-4) with different characteristics. Mutations in six genes have been identified to be associated with the various types. Herein, we describe a case of Waardenburg syndrome type 4 combined with open-angle glaucoma.
Case presentation: A 43-year-old Han Chinese man had undergone trabeculectomy due to progression of visual field impairment and unstable intraocular pressure in both eyes. Slit-lamp examination revealed diffuse iris hypopigmentation in the left eye and hypopigmentation of part of the iris in the right eye. Fundus examination showed red, sunset-like fundus due to a lack of pigmentation in the retinal pigment epithelium layer, diffuse loss of the nerve fiber layer, and an excavated optic nerve head with advanced-stage glaucoma. Imaging was performed using anterior segment optical coherence tomography to detect the iris configuration. In the heterochromic iris portion, the normal part of the iris showed a clear hyperreflective signal of the anterior border layer, while atrophy of the pigmented anterior border layer showed a hyporeflective area of the anterior surface resulting in reduced light absorption. Two mutations of the endothelin receptor type B gene were recognized in this study. The first (c.1111G>A on exon 7) leads to an amino acid change from glycine to serine at codon 371. Sanger verification revealed that this mutation is inherited from the mother. The other mutation (c.553G>A) leads to an amino acid change from valine to methionine at codon 185. Sanger verification showed that this mutation was inherited from the father.
Conclusion: Waardenburg syndrome shows a remarkable diversity in clinical presentation and morphology. This disease can also present with open-angle glaucoma. Sequencing analysis revealed two heterozygous mutations in the EDNRB gene in this patient, inherited from his mother and father, respectively. These two sites constitute a compound heterozygous variation.
Keywords: EDNRB gene; Genetics; Glaucoma; Waardenburg syndrome.
© 2022. The Author(s).