C9orf72 and Atrophy: The MAPT+ group showed the greatest degree of frontal (mean [SD] volume, left frontal: 12 683 [2345] mm3; right frontal: 13 235 [2015] mm3) and temporal (mean [SD] volume, left temporal: 8652 [1090] mm3; right temporal: 8628 [1237] mm3) atrophy at this stage, followed by GRN+ (eg, mean [SD] volume, right frontal: 13 679 [2448] mm3; right temporal: 9271 [1530] mm3) and C9orf72+ groups (eg, mean [SD] volume, right frontal: 14 012 [1485] mm3; right temporal: 9336 [734] mm3), with similar degrees of atrophy in GRN+ and C9orf72+ groups.