Intellectual disability - microarray and sequencing
Gene: MED13
The rating of this gene has been updated to Green following NHS Genomic Medicine Service approval.Created: 30 Jan 2023, 5:50 p.m. | Last Modified: 30 Jan 2023, 5:50 p.m.
Panel Version: 4.53
Additional cases published since initial review
PMID: 33931951 by Rogers et al, case report from an individual with a denovo missense variant p.Gly1150Glu who had more pronounced neurocognitive impairment and dysmorphismthan in previously reported individuals.
Patient identified in clinic with variant as reported in ClinVar.
Two additional cases would conclude enough evidence for MED13 to be GreenCreated: 25 May 2022, 5:56 p.m. | Last Modified: 25 May 2022, 5:56 p.m.
Panel Version: 3.1590
Phenotypes
Intellectual developmental disorder, autosomal dominant 61 OMIM:618009
Publications
Comment on list classification: Updated rating from Grey to Amber. Gene was added to panel and rated Amber by Konstantinos Varvagiannis. Not yet associated with a disorder in OMIM. Probable rating in Gene2Phenotype for 'Neurodevelopment disorder' based on PMID:29740699 (Snijders Blok et al., 2018) who report on 13 patients. 11 variants were de novo and 1 (patient B) was inherited from an affected mother (patient C). All patients had developmental delay to some extent (speech delay in most cases, with motor development delayed in 7/13). ID is mild/borderline in at least 9 cases. There is not a clear genotype-phenotype correlation between variants, and it's unclear how some variants are deleterious, and therefore Amber rating is appropriate until further studies are published.Created: 21 Sep 2019, 8:46 a.m. | Last Modified: 21 Sep 2019, 8:46 a.m.
Panel Version: 2.1043
Snijders Blok et al. (2018 - PMID: 29740699) report on 13 individuals with MED13 mutations.
Features included DD with speech difficulties (both universal) and motor delay in some. ID was observed in at least 9/13 and in most cases was in the borderline/mild range (moderate ID reported for 1 individual). Other features were ASD (5/13), ADHD, eye/vision abnormalities and in few individuals obstipation or congenital heart anomalies. Some possibly overlapping facial characteristics were also noted.
MED13 and MED13L are mutually exclusive components of the CDK8 kinase module that regulates the activity of the Mediator complex. The Mediator transmits signals from various transcription factors to RNA polymerase II (Pol II). Reversible binding of the CDK8 kinase controls Mediator - Pol II interaction (prevents Pol II recruitment) and thus acts as a molecular switch in Pol II - mediated transcription. DD and ID are features of the MED13L- and CDK8- related disorders.
3 stopgain, 2 frameshift, 6 missense variants and 1 in-frame deletion were reported. In 11 cases, the variants had occurred as de novo events, while 1 individual had inherited a nonsense variant from a similarly affected mother (unknown inheritance in her case).
Effect of a stopgain variant was studied with similar (total) transcript levels between the affected patient and his parents/controls upon qPCR. Sanger sequencing of cDNA amplicons was suggestive of the presence of an aberrant transcript at ~70% levels relative to the normal transcript. Truncated protein was undetectable by Western Blot in mononuclear blood cells from affected subjects. Total MED13 protein levels were not clearly different when comparing an affected individual with his unaffected parent (?).
Missense variants and the inframe deletion clustered either in the N- or the C-terminal domain, with the N-terminal ones all (T326I, T326del, P327S, P327Q / NM_005121.2 - NP_005112.2) affecting positions of a known phosphodegron sequence, important for the protein's ubiquitination and degradation. Another previously studied variant (T326A) had been shown to prevent degradation. As a result, the variants affecting aa 326-327 might lead to altered (increased) levels of MED13.
The remaining missense variants affected the C-terminal portion (Q2060L, A2064V).
As a result the impact of the different subcategories of variants remains unclear/inconclusive.
MED13 is not associated with any phenotype in OMIM. This gene is part of the DD panel of G2P, associated with "MED13 - Neurodevelopment disorder" (dis. confidence : probable / mutation consequence : LoF / GDD, speech/language delay, ID, autistic behavior among the assigned phenotypes).
MED13 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc).
ID is part of the phenotype of MED13-related disorder. However as the severity in most individuals - when present - was in the borderline/mild range (not relevant for the present panel) and/or the underlying effect of mutations remains unclear, amber rating seems more appropriate.
Sources: Radboud University Medical Center, Nijmegen, LiteratureCreated: 31 Aug 2019, 10:36 a.m. | Last Modified: 31 Aug 2019, 10:37 a.m.
Panel Version: 2.1021
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes
Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Attention deficit hyperactivity disorder; Abnormality of the eye; Constipation
Publications
Variants in this GENE are reported as part of current diagnostic practice
Tag Q2_22_rating was removed from gene: MED13. Tag Q2_22_NHS_review was removed from gene: MED13.
Source NHS GMS was added to MED13. Source Expert Review Green was added to MED13. Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Tag Q2_22_rating tag was added to gene: MED13. Tag Q2_22_NHS_review tag was added to gene: MED13.
Gene: med13 has been classified as Amber List (Moderate Evidence).
Gene: med13 has been removed from the panel.
gene: MED13 was added gene: MED13 was added to Intellectual disability. Sources: Radboud University Medical Center, Nijmegen,Literature Mode of inheritance for gene: MED13 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: MED13 were set to 29740699 Phenotypes for gene: MED13 were set to Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Attention deficit hyperactivity disorder; Abnormality of the eye; Constipation Penetrance for gene: MED13 were set to unknown Review for gene: MED13 was set to AMBER gene: MED13 was marked as current diagnostic