NRL-associated autosomal recessive retinopathy: novel variants expanding the phenotype, natural history and a comprehensive literature search.

BACKGROUND

Neural retina leucine zipper (NRL) is a crucial transcription factor that plays a key role in the development and differentiation of photoreceptor cells. A variant in this gene can cause a retinal phenotype known as Enhanced S cone Syndrome (ESCS). This study presents three novel autosomal recessive (ar) NRL variants and expands the clinical ophthalmic phenotype of NRL-associated retinopathy to include microphthalmia.

METHODS

Investigations included electrodiagnostic testing, best corrected visual acuity (BCVA), optical coherence tomography (OCT), ultra-wide field autofluorescence (UWAF), fundus imaging, and visual fields. PubMed, Cochrane library and ClinVar database were used for literature search.

RESULTS

Three patients (P1-3) from 2 different families with novel biallelic NRL variants were reported. P1 had novel homozygous likely-pathogenic NRL variant, p.(Glu86*). Genetic screening of both P2 and P3 identified a second and third novel heterozygous likely pathogenic variants, p.(Leu75Profs *19) and p.(Ser6Alafs *13). Multimodal imaging and functional studies in these patients were consistent with the classical features of ESCS with an additional feature of microphthalmia.

CONCLUSION

This study expands the genotype and phenotype of NRL-associated retinopathy and compares the ocular phenotype of our cohort with published NRL reports in the literature.