Rediscovering the Physical Exam Massive cervical heterotopic ossification and extra-articular temporo-mandibular joint ankylosis

A 7.5-year-old girl developed fibrodysplasia ossificans progressiva (FOP) at the age of 3 years. FOP, the most devastating form of heterotopic ossification (HO), is an autosomal dominant disease (most patients have de novo mutations) caused by mutations of the ACVR1/ALK2 gene on chromosome 2q24, which encodes the activin A receptor type I/activin-like kinase 2, a bone morphogenetic protein type I receptor.1 Beyond the typical congenitally malformed great toes (Figure 1), which are the earliest pathognomonic sign of FOP,2 her phenotype was aggressive.

source https://www.jpeds.com/article/S0022-3476(22)00490-5/fulltext?rss=yes