A 63-year-old man was hospitalized due to an abdominal pulsatile mass. Computed tomography revealed a saccular type abdominal aortic aneurysm, the diameter of which was 52 mm. A physical examination revealed prominent Achilles tendon thickness and plantar xanthomas. He was born in a family of consanguineous marriage, where his parents were second cousins. He had no familial history of high low-density lipoprotein cholesterol, tendon xanthomas, or premature atherosclerosis. Whole-exome sequencing assuming recessive inheritance determined his genetic diagnosis to be cerebrotendinous xanthomatosis caused by homozygous mutations (c.410G>A or p.Arg137Gln) in the cytochrome P450 subfamily 27 A1 (CYP27A1) gene.