Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) atypical hemolytic-uremic syndrome ?
    ### Response:
    Atypical hemolytic-uremic syndrome is a disease that primarily affects kidney function. This condition, which can occur at any age, causes abnormal blood clots (thrombi) to form in small blood vessels in the kidneys. These clots can cause serious medical problems if they restrict or block blood flow.
    