Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to Stargardt macular degeneration ?
    ### Response:
    In most cases, Stargardt macular degeneration is caused by mutations in the ABCA4 gene. Less often, mutations in the ELOVL4 gene cause this condition. The ABCA4 and ELOVL4 genes provide instructions for making proteins that are found in light-sensing (photoreceptor) cells in the retina.
    