POC1B-associated cone-rod dystrophy with bilateral optic disc swelling: A novel clinical observation

To report a series of genetically confirmed cone and cone-rod dystrophy cases associated with POC1 Centriolar Protein B (POC1B) mutations, including two cases presenting with bilateral optic disc swelling.

In the first family, three affected siblings had a homozygous nonsense variant in POC1B (NM_172240.3:c.672C > G; p.Tyr224∗), classified as pathogenic. Two of these cases presented with bilateral optic disc swelling confirmed by fundus examination and optical coherence tomography, accompanied by features consistent with cone dysfunction on full-field ERG. In the second family, three affected siblings carried a homozygous frameshift variant in POC1B (NM_172240.3:c.991del; p.Arg331Glufs∗13), also classified as pathogenic. These patients demonstrated early-onset visual loss, photophobia, and cone dysfunction without optic disc swelling. All identified variants were consistent with autosomal recessive inheritance and validated by Sanger sequencing.

Bilateral optic disc swelling is a rare manifestation in COD/CORD and is rarely reported in association with POC1B variants. Our cases expand the phenotypic spectrum of POC1B-associated retinopathies and highlight the importance of considering optic disc swelling as a possible, albeit rare, feature in COD/CORD.