ABCA4 and severe early-childhood-onset retinal dystrophy: ,14,15,16 The onset of the first symptoms of STGD1 disease in individuals homozygous for the ABCA4 c.5461-10T>C variant is often in the first decade of life, after which the progress of the disease can sharply accelerate and lead to legal blindness between the ages of 20 and 30.7