Abstract
Purpose :
To assess rod-mediated ERG responses to full-field stimuli in pediatric patients with biallelic variants in ABCA4. Typically, the conspicuous clinical feature in ABCA4 retinal disease is maculopathy.
Methods :
Of our 44 patients with biallelic variants in ABCA4, 40 had at least one ERG test. The age at ERG test was 1.26–22.12 (median: 11.09) years, except for one patient who was tested at age 58 years. The variants in ABCA4 ranged from double nulls (producing no protein) to less severe. We calculated the amplitude and sensitivity of the rod photoresponse (Rrod and Srod) from the a-wave and the postreceptor activity (Vmax, 1/σ) from the b-wave.
Results :
Among those with double null variants, nearly all (92.5%) had Rrod values below the 95% prediction limit for normal (PLN), and 67.5% had Srod values below the PLN. By contrast, among those with mild mutations, the rod photoresponse deficits were uncommon. As for the postreceptor response parameters, even in the case of the double nulls, deficits in Vmax were less frequent. All values of the postreceptor response parameters (Vmax, 1/σ) were normal in those with mild variants in ABCA4.
Conclusions :
Significant deficits in rod-mediated ERG responses to full-field stimuli are common, even though the obvious clinical feature is maculopathy. The frequent deficits in rod photoreceptor activity are likely indicators of the pathobiology of ABCA4 retinal disease. ABCA4 is expressed in both rods and cones.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.