Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to dopamine beta-hydroxylase deficiency ?
    ### Response:
    Mutations in the DBH gene cause dopamine -hydroxylase deficiency. The DBH gene provides instructions for producing the enzyme dopamine -hydroxylase. This enzyme converts dopamine to norepinephrine, both of which are chemical messengers (neurotransmitters) that transmit signals between nerve cells.
    