Increased myo-inositol/creatine levels have been observed in healthy apolipoprotein E E4 genotype (APOE ε4) carriers with normal CSF Aβ42 levels in comparison to ε4 non-carriers, signifying the importance of myo-inositol levels in assessing AD before a noticeable amyloid pathology [176]. The gene discussed is APOE; the disease is Alzheimer disease.