They exhibited typical iPSC characteristics with a high nuclear-to-cytoplasmic ratio, expressed pluripotency markers NANOG, OCT4, SSEA4 and TRA-1 (Fig. 2c) and showed differentiation potential marked by AFP, SMA and TUJ1 (Supplementary Fig. 1c), without significant difference between BCD and WT. The gene discussed is SMN1; the disease is Bietti crystalline dystrophy.