School of Science
National Health and Medical Research Council of Australia / Macular Disease Foundation Australia / Perth Children's Hospital-Telethon research grant / McCusker Charitable Foundation (F.K.C.) / Miocevich Retina Fellowship (R.C.H.J.) / Retina Australia (J.A.T., T.L., J.N.D.R., T.L.M.)
NHMRC Numbers : GNT1116360, GNT1188694, GNT1054712, MRF1142962
Purpose: To investigate concordance in symptom onset, area of dark autofluorescence (DAF), and growth rate (GR) between Stargardt disease siblings at an age-matched time point. Methods: In this retrospective longitudinal study of sibling pairs with identical biallelic ABCA4 variants, age at symptom onset, best-corrected visual acuity, atrophy area, and effective radius of DAF on ultra-widefield fundus autofluorescence were recorded. Absolute intersibling differences for both eyes were compared with absolute interocular differences using the Mann-Whitney test. Results: Overall 39 patients from 19 families were recruited. In 16 families, age-matched best-corrected visual acuity and DAF were compared between siblings. In 8 families, DAF GR was compared. The median (range) absolute difference in age at symptom onset between siblings was 3 (0-35) years. Absolute intersibling differences in age-matched best-corrected visual acuity were greater than interocular differences (P = 0.01). Similarly, absolute intersibling differences in DAF area and radius were greater than interocular differences (P = 0.04 for area and P = 0.001 for radius). Differences between absolute interocular and intersibling GR were not statistically significant (P = 0.44 for area GR and P = 0.61 for radius GR). Conclusion: There was significant discordance in age-matched best-corrected visual acuity and DAF beyond the expected limits of interocular asymmetry. Lack of significant intersibling differences in GR warrants further investigation.
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