Primary muscle involvement in a 15-year-old girl with the recurrent homozygous c.362dupC variant in FKBP14.

Kyphoscoliotic Ehlers-Danlos syndrome associated with FKBP14 (FKBP14-kEDS) is an ultrarare autosomal recessive disorder reported in less than 30 individuals so far. In its original description, emphasis was put on the mild muscle involvement. Further reports confirm that FKBP14-kEDS is distinguishable from primary muscle disorders by the lack of progressive muscle disease. We report a 15-year-old girl with FKBP14-kEDS as a result of the recurrent c.362dupC variant, who also showed severe involvement of the lower limb muscles. She never attained autonomous walking and presented significant lower limb weakness. Lower limb magnetic resonance imaging showed a pattern of multiple muscle involvement. Further musculoskeletal assessment revealed significant bone mass density reduction of the spine, unilateral congenital hip dysplasia, and occipitoatlantoaxial instability. This patient points out the existence of a wider phenotypic spectrum of FKBP14-kEDS to include early onset muscle disease.