Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Angelman syndrome ?
    ### Response:
    What causes Angelman syndrome? Angelman syndrome is caused by a loss of function of a gene called UBE3A on chromosome 15. The exact mechanism that causes this loss of function is complex. People normally inherit one copy of the UBE3A gene from each parent. Both copies of this gene are turned on (active) in many of the body's tissues.
    