Atypical Fibrodysplasia Ossificans Progressiva with G328E Variant and Digit Reduction Abnormalities

Case: Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant musculoskeletal disorder with progressive heterotopic ossification within soft connective tissues causing ankyloses and unique skeletal malformations of the big toes, which represent a birth hallmark for the disease. The classic variant is c.617G>A (p.Arg206His). We report 2 atypical FOP cases showing severe digit reduction, associated with a c.983G>A (p.Gly328Glu) variant in exon 8 of the ACVR1 gene. Conclusion: FOP should be ruled out in patients presenting with restricted movements of joints and spine and reduction of digits by clinical examination and molecular genetic analysis to allow preventive steps and slow clinical deterioration.