Bone Abstracts

Background: Osteogenesis imperfecta (OI) type VI is a rare recessive disease that may present with long bone fractures in early childhood. Bone in this condition is particularly brittle; the resulting pattern of long bone fractures and lack of distinct radiographic findings can make the diagnosis less obvious than in other types of OI. We report 2 unrelated children who presented with long bone fractures and were suspected of having suffered physical abuse with removal of parents’ custodial rights.

Presenting problem: Patient 1 was the second child of first cousins. He started walking at 12 m. His first fracture was of the clavicle aged 13 m. Humerus, fibula and multiple rib fractures had occurred by 2.5 yrs. He had off-white sclerae and ligamentous laxity. Patient 2 was born to healthy unrelated parents. He started walking at 12m. His first fracture was of the clavicle aged 13 m. Femur, fibula, pars of C2 vertebra and multiple rib fractures had occurred by 2.0 yrs. He had off-white sclerae, ligamentous laxity and was relatively tall (91st percentile).

Management: Both had normal bone biochemistry (including 25OH-vitamin D). Skeletal surveys undertaken at presentation (2.3 and 1.8 yrs, respectively) did not provide any clear indication of underlying bone disease. Targeted OI exome panel was undertaken in both patients. Patient 1 was homozygous for c.499del (p.Arg167fs) SERPINF1 variant. Patient 2 was compound heterozygous for c.582_585dup (p.Thr196Valfs*8), c.272C>A (p.Ala91Asp) SERPINF1 variants. Patient 1 developed vertebral fractures aged 5 yrs. Pamidronate was started at 6 yrs. Patient 2 developed unequivocal vertebral wedging by 2.5 yrs, underwent bone biopsy and was started on zoledronic acid.

Discussion: OI type VI patients have commonly been reported to sustain their first fractures between 6 and 18 m. As in our two cases, such a presentation, together with a relative lack of clinical and radiological clues to the diagnosis, can lead to suspicion of physical abuse that may be difficult to refute without genetic screening. Our experience suggests that careful evaluation of fracture history, family history (including consanguinity), together with examination specifically for off-white sclerae, ligamentous laxity and vigilance for early radiographic signs of vertebral deformity can distinguish children with OI type VI.

Disclosure: The authors declared no competing interests