- Reported worsening cognitive decline and gait disturbance- Physical examination identified bilateral Achilles tendon xanthomas- Follow-up MMSE score: 22- Bilateral cataracts and osteoporosis were diagnosed- NGS genetic analysis identified heterozygous pathogenic variants (c.1214G>A, c.1421G>A) in the CYP27A1 gene, confirming CTX. This evidence concerns the gene CYP27A1 and osteoporosis.