Type V Osteogenesis Imperfecta in an Indian Cohort: Phenotypic Variability and Radiological Insights in...

Osteogenesis imperfecta type V is a rare autosomal dominant form of osteogenesis imperfecta caused by the recurrent c.-14C>T mutation in the IFITM5 gene. This mutation affects osteoblast function and mineralization, leading to distinctive skeletal manifestations that differ from classical collagen-related OI. This study describes the clinical, radiological, and genetic characteristics of Indian children with OI type V, and assesses phenotypic variability and treatment outcomes.

A retrospective observational study was conducted in six Indian children with genetically confirmed OI type V. Clinical data, fracture history, radiological findings, and treatment response to intravenous pamidronate were analyzed.

All six patients harbored the recurrent IFITM5 c.-14C>T variant. The age at first fracture ranged from birth to three years, with variable fracture frequency and progressive skeletal deformities. Hallmark features such as hyperplastic callus formation, ossification of interosseous membranes, and radial head dislocation were consistently observed. Wormian bones were present in five patients. Progressive spinal deformities, including scoliosis and kyphosis, developed in older children. Notably, none of the patients exhibited blue sclerae or dentinogenesis imperfecta. Familial transmission across three generations was observed in one case. All patients received intravenous pamidronate therapy, which resulted in initial improvement in bone mineral density; however, it did not prevent long-term skeletal complications in some individuals.

This first Indian cohort highlights significant phenotypic variability in OI type V despite a uniform underlying mutation. Recognition of its distinctive clinical and radiological features is critical for accurate diagnosis, appropriate genetic counselling, and optimized management strategies.