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Colman M, Vroman R, Dhooge T, Malfait Z, Symoens S, Burnyté B, Nampoothiri S, Kariminejad A, Malfait F, Syx D. Kyphoscoliotic Ehlers-Danlos syndrome caused by pathogenic variants in FKBP14: Further insights into the phenotypic spectrum and pathogenic mechanisms. Hum Mutat 2022; 43:1994-2009. [PMID: 36054293 DOI: 10.1002/humu.24456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 07/12/2022] [Accepted: 08/29/2022] [Indexed: 01/25/2023]
Abstract
The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of heritable connective tissue diseases. The autosomal recessive kyphoscoliotic EDS results from deficiency of either lysyl hydroxylase 1 (encoded by PLOD1), crucial for collagen cross-linking; or the peptidyl-prolyl cis-trans isomerase family FK506-binding protein 22 kDa (FKBP22 encoded by FKBP14), a molecular chaperone of types III, IV, VI, and X collagen. This study reports the clinical manifestations of three probands with homozygous pathogenic FKBP14 variants, including the previously reported c.362dupC; p.(Glu122Argfs*7) variant, a novel missense variant (c.587A>G; p.(Asp196Gly)) and a start codon variant (c.2T>G; p.?). Consistent clinical features in the hitherto reported individuals (n = 40) are kyphoscoliosis, generalized joint hypermobility and congenital muscle hypotonia. Severe vascular complications have been observed in 12.5%. A previously unreported feature is microcornea observed in two probands reported here. Both the c.587A>G and the c.362dupC variant cause complete loss of FKBP22. With immunocytochemistry on dermal fibroblasts, we provide the first evidence for intracellular retention of types III and VI collagen in EDS-FKBP14. Scratch wound assays were largely normal. Western blot of proteins involved in the unfolded protein response and autophagy did not reveal significant upregulation in dermal fibroblasts.
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Affiliation(s)
- Marlies Colman
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Robin Vroman
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Tibbe Dhooge
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Zoë Malfait
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Sofie Symoens
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Biruté Burnyté
- Center for Medical Genetics, Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania
| | - Sheela Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences & Research Centre, Kerala, India
| | | | - Fransiska Malfait
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Delfien Syx
- Department of Biomolecular Medicine, Center for Medical Genetics, Ghent University, Ghent, Belgium
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