Abstract: The present application relates to expression cassette combinations and uses thereof. The expression cassette combination comprises a first expression cassette and a second expression cassette, wherein the first expression cassette can express an N-terminal truncated version of an ABCA4 protein, the second expression cassette can express a C-terminal truncated version of an ABCA4 protein, and the N-terminal truncated version of the ABCA4 protein and the C-terminal truncated version of the ABCA4 protein can possess the biological functions of a complete ABCA4 protein without forming the complete ABCA4 protein therefrom.

Abstract: The present application provides a PRPF31 variant comprising an exogenous nuclear localization (NLS) domain, wherein the exogenous NLS domain comprises an amino acid sequence set forth in any of SEQ ID NOs. 3 to 4. The PRPF31 variant can improve the biological activity of a retinal pigment epithelium (RPE) cell, and can treat a disease caused by PRPF31 gene mutation.