A novel homozygous c.67C>T variant in retinol binding protein 4 (RBP4) associated with retinitis pigmentosa and childhood acne vulgaris
Cehajic-Kapetanovic J., Jasani KM., Shanks M., Clouston P., MacLaren RE.
© 2020, © 2020 Taylor & Francis Group, LLC. Background: The retinol binding protein 4 (RBP4) is essential in delivering retinol to the retinal pigment epithelium and normal functioning of the visual cycle. Homozygous mutations in the RBP4 gene lead to severe retinitis pigmentosa that is phenotypically indistinguishable from retinitis pigmentosa caused by other recessive mutations. Methods: Case Report. Purpose: To report a novel homozygous RBP4 c.67 C > T variant in a case of retinitis pigmentosa associated with severe childhood acne vulgaris. Results: A 49-year old Caucasian man with a family history of retinitis pigmentosa, presented with low vision and night blindness from early childhood. Fundus examination showed findings typical of recessive retinitis pigmentosa. Next generation sequencing analysis revealed a novel homozygous RBP4 c.67 C > T variant. Examination of patient’s back showed widespread scaring and hyperpigmentation secondary to severe childhood-onset acne vulgaris. Patient’s affected brother, positive for the same homozygous variant, also had a history of severe acne vulgaris whereas the unaffected brother did not, confirming that mutations in RBP4 segregated with the acne vulgaris phenotype in this family. Conclusions: We describe a case of retinitis pigmentosa associated with acne vulgaris and highlight the role of this systemic manifestation of retinol deficiency in confirming pathogenicity of the novel variant. Given the small size of the genomic RBP4 DNA (0.6kb), gene therapy using an adeno-associated viral vector with subretinal delivery has great potential to treat this severe childhood-onset blinding retinal disease. In addition, ubiquitous expression of RBP4 supports the development of in vitro functional assays to test the vector potency for clinical use.