IFITM5 and osteogenesis imperfecta: We present this case to highlight the novelty of this association, improve recognition of the distinguishing features, and prevent future misdiagnosis.<h4>Case presentation</h4>A 23-year-old female with <i>IFITM5</i>-related OI, confirmed by molecular testing showing heterozygosity for a pathogenic <i>IFITM5</i> mutation (c.119C>T, p.Ser40Leu; parental testing to determine inheritance was not performed) presented to our Comprehensive Cancer Center in May 2025 with localized groin pain, later diagnosed as a nondisplaced pelvic fracture.