To identify effects of Col4a1/a2 deficiency on (1) aortas, which could prime AAA development and/or (2) AAA lesions per se, we analyzed unchallenged aortas and AAA lesions from Col4a1/a2+/− and Col4a1/a2+/+ mice by LC–MS/MS. Here, COL4A1 is linked to triple-A syndrome.