Endocrine Abstracts

Osteogenesis imperfecta (OI) is a heritable skeletal disorder caused by defective bone formation. OI type V (MIM#:614757) develops due to mutation in the IFITM. Mutation c.-14C >T in the IFITM5 is more common whereas only five reported patientshave a c.119C >T mutation. Patients with IFITM5:c.119C >T mutation usually have low-traumatic fractures in the prenatal period of development, severe limb and chest deformities, short height, vertebral fractures and inability to move independently in a childhood.

We present acase of an adult patient with OI type V due to a rare mutation p.119C > T:p.S40L in the IFITM5. A 32-year-old female (height, 95 cm; weight, 30 kg) was hospitalized with back pain, pain in joints and limited ability to move in a wheelchair. She had severe chest and long bonesdeformities, and joints contracture. CT scan showed the presence of ossifications of the interosseous membrane between the ulna and radius; multiple vertebral fractures. The patient denied relatives with similar clinical features, she did not have hearing loss, blue sclerae ordentinogenesis imperfecta. The patient sufferedher first fractureat the prenatal period of development. During childhood she had numerous fractures: long lower and upper limb bones, ribs, clavicle. At the age of 7 she had osteosynthesis on both femurs and tibiae. She became immobile at the age of 13.The patient followed treatment with zoledronic acid, calcium and vitamin D supplements from 26 to 28 years of age and then teriparatide 20 mg/day. The last fracture was diagnosed at the age of 29. Serum calcium, phosphate, creatinine, vitamin D, C-terminal telopeptide of type I collagen, PTH were within the reference ranges, but osteocalcin was slightly elevated 47.42 ng/ml (11–43).

Conclusion: This is a case of sever OI type V surviving into adulthood. OI is a clinically and genetically heterogeneous disease, so testing of pathogenic variants of the IFITM5 may be useful.