Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Adult-onset vitelliform macular dystrophy ?
    ### Response:
    What causes adult-onset vitelliform dystrophy? Historically, adult-onset vitelliform macular dystrophy (AVMD) was defined as a genetic disorder; however, recent studies have concluded that only a minority of cases have an identified genetic cause, suggesting that there might be other underlying causes of environmental origin, genetic origin, or a mix of genetics and environment (multifactorial).
    