rs879255528

Positions:

• chrX-71137821-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_005120.3(MED12):​c.5922G>T​(p.Gln1974His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 22)
• Consequence: MED12 NM_005120.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3 B:1 O:1
• Conservation: PhyloP100: 2.99

Genes affected

MED12 (HGNC:11957): (mediator complex subunit 12) The initiation of transcription is controlled in part by a large protein assembly known as the preinitiation complex. A component of this preinitiation complex is a 1.2 MDa protein aggregate called Mediator. This Mediator component binds with a CDK8 subcomplex which contains the protein encoded by this gene, mediator complex subunit 12 (MED12), along with MED13, CDK8 kinase, and cyclin C. The CDK8 subcomplex modulates Mediator-polymerase II interactions and thereby regulates transcription initiation and reinitation rates. The MED12 protein is essential for activating CDK8 kinase. Defects in this gene cause X-linked Opitz-Kaveggia syndrome, also known as FG syndrome, and Lujan-Fryns syndrome. [provided by RefSeq, Aug 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), MED12. . Gene score misZ 6.5797 (greater than the threshold 3.09). GenCC has associacion of gene with MED12-related intellectual disability syndrome, X-linked intellectual disability with marfanoid habitus, blepharophimosis - intellectual disability syndrome, MKB type, FG syndrome 1, cholestasis-pigmentary retinopathy-cleft palate syndrome.
• BP4: Computational evidence support a benign effect (MetaRNN=0.24117601).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MED12	NM_005120.3	c.5922G>T	p.Gln1974His	missense_variant	41/45	ENST00000374080.8	NP_005111.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MED12	ENST00000374080.8	c.5922G>T	p.Gln1974His	missense_variant	41/45	1	NM_005120.3	ENSP00000363193	P4

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 22

Bravo AF: 0.00000756

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3 Benign:1 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 04, 2016

The p.Q1974H variant (also known as c.5922G>T), located in coding exon 41 of the MED12 gene, results from a G to T substitution at nucleotide position 5922. The glutamine at codon 1974 is replaced by histidine, an amino acid with highly similar properties. In a family study, this variant was observed to co-segregate with another alteration in the OGT gene in three brothers with severe non-syndromic intellectual deficiency and mild dysmorphic features (Bouazzi H et al. Clin Case Rep. 2015;3(7):604-9). In the same study, this variant, but not the OGT alteration, was confirmed in their mother who was described to have language delays and no dysmorphic features. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6230 samples with coverage at this position. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this variant remains unclear. -

FG syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 11, 2021

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MED12 protein function. ClinVar contains an entry for this variant (Variation ID: 252965). This missense change has been observed in individual(s) with non-syndromic intellectual disability (PMID: 26273451). This variant is not present in population databases (ExAC no frequency). This sequence change replaces glutamine with histidine at codon 1974 of the MED12 protein (p.Gln1974His). The glutamine residue is highly conserved and there is a small physicochemical difference between glutamine and histidine. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Jul 01, 2018

- -

Intellectual disability Benign:1

Benign, no assertion criteria provided

clinical testing

Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital

Dec 06, 2017

Variant inherited from healthy grandfather of index patient -

FG syndrome 1 Other:1

not provided, no classification provided

literature only

GeneReviews

-

Reported in male sibs with nonspecific intellectual disability -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.20
BayesDel_addAF	Uncertain	0.027	T
BayesDel_noAF	Benign	-0.20
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Benign	0.32	T;.;D
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.82	T;T;T
M_CAP	Uncertain	0.18	D
MetaRNN	Benign	0.24	T;T;T
MetaSVM	Uncertain	-0.14	T
MutationAssessor	Benign	1.6	.;.;L
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.56	T
PROVEAN	Benign	-1.2	.;N;N
REVEL	Benign	0.29
Sift	Benign	0.094	.;T;T
Sift4G	Uncertain	0.019	D;D;D
Polyphen		0.97	D;P;P
Vest4		0.17
MutPred		0.19		.;.;Loss of solvent accessibility (P = 0.0238);
MVP		0.89
MPC		1.5
ClinPred		0.80	D
GERP RS		4.1
Varity_R		0.45
gMVP		0.19

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.14		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs879255528; hg19: chrX-70357671;