Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to familial hypobetalipoproteinemia ?
    ### Response:
    Most cases of FHBL are caused by mutations in the APOB gene. This gene provides instructions for making two versions of the apolipoprotein B protein: a short version called apolipoprotein B-48 and a longer version known as apolipoprotein B-100. Both of these proteins are components of lipoproteins, which transport fats and cholesterol in the blood.
    