Electroretinography responses of both patients were dominated by short-wavelength-sensitive mechanisms, with no detectable rod function, similar to the ERG responses of individuals with enhanced S-cone syndrome (ESCS) due to NR2E3 mutations.
Mutations in NR2E3 typically lead to recessive enhanced S-cone syndrome (ESCS), where affected individuals show higher sensitivity to short wavelength light and early onset rod dysfunction.
This data coincides with studies in humans showing that mutations in Nr2e3 result in a unique type of retinal degeneration known as enhanced S-cone syndrome, where patients have a 30-fold increase in S-cone sensitivity compared to normal.
The purpose of this study is to report the ophthalmic features of a 25-year-old Portuguese male with a typical ESCS phenotype and a novel homozygous NR2E3 mutation.
The subject (Patient A) with no detected NR2E3 mutation had features not usually associated with ESCS, in particular moderate rod photoreceptor function in peripheral retina and an abnormally thick retinal nerve fibre layer.
The authors previously reported details on enhanced S-cone syndrome (ESCS) in a 23-year-old male patient with a homozygous NR2E3 mutation (p.Q350X) who developed large bilateral macular retinoschisis.
In 94% of a cohort of ESCS probands we found mutations in NR2E3 (also known as PNR), which encodes a retinal nuclear receptor recently discovered to be a ligand-dependent transcription factor.
To determine the relationship between cone deactivation kinetics in patients with the enhanced S cone syndrome (ESCS) caused by mutations in NR2E3 and the immunoreactivity to G-protein-coupled receptor kinase 1 (GRK1) and GRK7.
The p.E121K variant of NR2E3, which reportedly caused enhanced S-cone syndrome (ESCS) in Caucasians, was found concurrently in RP patients (13.4%) and control subjects from Hong Kong (10.5%) and Beijing (12.8%).
The diagnosis of enhanced S-cone syndrome was suggested by the uniquely abnormal electroretinographic pattern and was confirmed by the finding of homozygous NR2E3 mutations.