Inherited and de novo biallelic pathogenic variants in COL11A1 result in type 2 Stickler syndrome with severe hearing loss

Autor: Adrian Lomas, Allan J. Richards, Pradeep Vasudevan, Stephen Abbs, Martin P. Snead, Thomas R. W. Nixon, Philip Alexander, Annie McNinch
Přispěvatelé: Nixon, Thomas [0000-0003-2790-1135], Richards, Allan J [0000-0003-1511-3836], Alexander, Philip [0000-0002-2399-4154], Snead, Martin P [0000-0003-0042-8659], Apollo - University of Cambridge Repository
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Molecular Genetics & Genomic Medicine, Vol 8, Iss 9, Pp n/a-n/a (2020)
Molecular Genetics & Genomic Medicine
ISSN: 2324-9269
Popis: Background Type 2 Stickler syndrome is usually a dominant disorder resulting from pathogenic variants in COL11A1 encoding the alpha 1 chain of type XI collagen. Typical molecular changes result in either substitution of an obligate glycine within the Gly‐Xaa‐Yaa amino acid sequence repeat region of the molecule, mRNA missplicing or deletions/duplications that typically leaves the message in‐frame. Clinical features include myopia, retinal detachment, craniofacial, joint, and hearing problems. Fibrochondrogenesis is also a COL11A1 related disorder, but here disease‐associated variants are recessive and may be either null alleles or substitutions of glycine, and the condition is usually lethal in infancy. Methods The patient was assessed in the NHS England Stickler syndrome diagnostic service. DNA from the patient and family were analyzed with Next Generation Sequencing on a panel of genes known to cause Stickler Syndrome. The effect of sequence variants was assessed using minigene analysis. Allele‐specific RT‐PCR was performed. Results This patient had clinical type 2 Stickler syndrome but with severe hearing loss and severe ocular features including retinal atrophy and retinal tears in childhood. We identified a de novo in frame deletion of COL11A1 (c.4109_4126del) consistent with dominantly inherited Stickler syndrome but also a second inherited variant (c.1245+2T>C), on the other allele, affecting normal splicing of COL11A1 exon 9. Conclusion Exon 9 of COL11A1 is alternatively expressed and disease causing changes affecting only this exon modify the phenotype resulting from biallelic COL11A1 disease‐associated variants and, instead of fibrochondrogenesis, produce a form of Stickler syndrome with severe hearing loss. Disease phenotypes from de novo pathogenic variants can be modified by inherited recessive variants on the other allele. This highlights the need for functional and family analysis to confirm the mode of inheritance in COL11A1‐related disorders, particularly for those variants that may alter normal pre‐mRNA splicing.
We describe an individual with a de novo in frame deletion of COL11A1 consistent with dominantly inherited Stickler syndrome but also a second inherited variant affecting normal splicing of exon 9. Allele specific RT‐PCR showed that these two changes are bi‐allelic. Like the previously reported recessive cases involving exon 9 variants, this patient also had a phenotype of Stickler syndrome with severe hearing loss and also more severe ocular features.
Databáze: OpenAIRE
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