CDH23-associated Usher syndrome: genotype-phenotype correlations

To identify retinal genotype-phenotype correlations in CDH23-associated Usher syndrome (USH1D), review of clinical notes, and retinal imaging including fundus autofluorescence (FAF) and optical coherence tomography (OCT). Subjects were grouped according to the combination of CDH23 variants-two loss-of-function (G1), one loss-of-function, and one non-loss-of-function (G2) or two non-loss-of-function variants (G3)-and parameters were compared. The mean age of onset (range) for patients in G1 was 8.9 (1-14), which was lower but not significantly different (p = 0.19). The mean LogMAR BCVA (range, ± SD) for G1 was 0.41 (0.2-0.9, ± 0.25), which was not significant (p = 0.1). Only one patient in G3 developed ellipsoid zone width (EZW) loss. Neither the mean outer nuclear layer (ONL) thickness at baseline, nor at the last vist were significantly different between groups (p = 0.84). The mean annual rate (± SD, 95% CI) of ONL thickness loss was 2.15 µm/y (± 2.2, [0.65-3.6]) in G1, 1.22 µm/y (± 1.6, [-1.3-3.8]) in G2 and 1.5 µm/y (± 1.5, [0.06-2.9]) in G3, which was not significantly different (p = 0.66). Although this data suggests a trend to a milder phenotype in patients with at least one non-LoF variant, none of the parameters assessed found statistically significant differences.