1. Qualitative and quantitative analysis of MED12 c.887G>A causing both missense and splicing variants in X-linked Ohdo syndrome.
- Author
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Togi S, Ura H, and Niida Y
- Subjects
- Child, Female, Humans, Male, Abnormalities, Multiple, Blepharoptosis, Cleft Palate genetics, Cleft Palate pathology, Deafness genetics, Deafness pathology, Genetic Diseases, X-Linked genetics, Genetic Diseases, X-Linked pathology, Heart Defects, Congenital, Intellectual Disability genetics, Intellectual Disability pathology, Mutation, Missense, Pedigree, Phenotype, Vesico-Ureteral Reflux genetics, Vesico-Ureteral Reflux pathology, X Chromosome Inactivation genetics, Blepharophimosis genetics, Blepharophimosis pathology, Mediator Complex genetics, RNA Splicing genetics
- Abstract
The phenotypes associated with MED12 pathogenic variants are diverse. Male patients usually have missense variants, but the effects of base substitutions on mRNA splicing have not been investigated. Here, we report a Japanese brother with intellectual disability, characteristic facial appearance with blepharophimosis, cleft palate, Fallot tetralogy, vesicoureteral reflux, and deafness. A known missense pathogenic variant was detected in MED12, NM_005120.3:c.887G>A p.(Arg296Gln), and X-linked Ohdo syndrome was diagnosed in combination with their phenotype. mRNA splicing of MED12 was evaluated qualitatively and quantitatively using long-range PCR-based targeted RNA sequencing (reverse transcribed long amplicon sequencing), and it was shown that this missense variant simultaneously causes aberrant splicing of the 42-bp in-frame deletion in exon 7, r.847_888del, which accounts for approximately 30% of the mRNAs in both siblings. The X chromosome inactivation study showed that the X chromosome carrying the mutant allele was 100% inactivated in the carrier mothers. mRNA level analysis is essential for the accurate interpretation of the effects of variants. In this case, the MED12 protein function may be reduced by more than just an amino acid substitution, resulting in the patients with the most severe phenotype of MED12-related syndrome in males., (© 2024 Wiley Periodicals LLC.)
- Published
- 2024
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