Atrophy varied according to whether the CSF AD biomarkers were positive or not, with especially prominent ventriculomegaly in cases with CBS-AD (marginal mean [SD] volume: 35.80 [19.25] mL in controls; 60.81 [18.83] mL in CBS-4RT; 75.75 [18.81] mL in CBS-AD). The gene discussed is CBS; the disease is Alzheimer disease.