Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) familial dilated cardiomyopathy ?
    ### Response:
    Familial dilated cardiomyopathy is a genetic form of heart disease. It occurs when heart (cardiac) muscle becomes stretched out in at least one chamber of the heart, causing the open area of the chamber to become enlarged (dilated). As a result, the heart is unable to pump blood as efficiently as usual.
    