Early Motor Delay: An Outstanding, Initial Sign of Osteogenesis Imperfecta Type 1

INTRODUCTION Osteogenesis imperfect (OI) is a heterogeneous and complex connective tissue disorder that manifests with low bone density and fragility. More than 15 types of OI have been distinguished on a clinical and molecular basis, but the classical clinical classification previously proposed in Types 1-4 with the recent inclusion of Type 5 appears to be more suitable. The diagnosis is mainly made on clinical and radiographic findings with fractures caused by mild trauma, bowing deformities of long bones, and growth deficiency. Non-skeletal features of the disorder include blue sclerae, hearing loss, decreased pulmonary function, cardiac valvular regurgitation, and muscle weakness. CASE REPORT We report on a toddler girl affected by OI Type 1 who suffered from marked muscle weakness as the first initial sign, which led us to follow the diagnostic checklist for hypotonic children. The typical signs of the disorder later became evident and consistent with this diagnosis, including bone fractures and blue sclerae. CONCLUSION Early muscle weakness, previously unreported sign, may be an initial manifestation of OI, to be included in the differential diagnosis of disorders that cause hypotonia in childhood.