NM_004830.4:c.3077T>G

Variant names:

• chr6-131594254-A-C
• rs1554253506
• NM_004830.4:c.3077T>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_004830.4(MED23):​c.3077T>G​(p.Leu1026Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L1026P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MED23 NM_004830.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.03
• Publications: 0 publications found

Genes affected

MED23 (HGNC:2372): (mediator complex subunit 23) The activation of gene transcription is a multistep process that is triggered by factors that recognize transcriptional enhancer sites in DNA. These factors work with co-activators to direct transcriptional initiation by the RNA polymerase II apparatus. The protein encoded by this gene is a subunit of the CRSP (cofactor required for SP1 activation) complex, which, along with TFIID, is required for efficient activation by SP1. This protein is also a component of other multisubunit complexes e.g. thyroid hormone receptor-(TR-) associated proteins which interact with TR and facilitate TR function on DNA templates in conjunction with initiation factors and cofactors. This protein also acts as a metastasis suppressor. Several alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Jul 2012]

MED23 Gene-Disease associations (from GenCC):

• intellectual disability, autosomal recessive 18

  Inheritance: AR Classification: STRONG, MODERATE, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P
• syndromic intellectual disability

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen
• autosomal recessive non-syndromic intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 9 curated pathogenic missense variants (we use a threshold of 10). The gene has 0 curated benign missense variants. Gene score misZ: 4.7291 (above the threshold of 3.09). Trascript score misZ: 5.9944 (above the threshold of 3.09). GenCC associations: The gene is linked to intellectual disability, autosomal recessive 18, syndromic intellectual disability, autosomal recessive non-syndromic intellectual disability.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.924

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_004830.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MED23	NM_004830.4	MANE Select	c.3077T>G	p.Leu1026Arg	missense	Exon 23 of 29	NP_004821.2
	MED23	NM_001376517.1		c.3095T>G	p.Leu1032Arg	missense	Exon 24 of 30	NP_001363446.1
	MED23	NM_015979.4		c.3095T>G	p.Leu1032Arg	missense	Exon 24 of 31	NP_057063.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MED23	ENST00000368068.8	TSL:1 MANE Select	c.3077T>G	p.Leu1026Arg	missense	Exon 23 of 29	ENSP00000357047.3
	MED23	ENST00000354577.8	TSL:1	c.3095T>G	p.Leu1032Arg	missense	Exon 24 of 31	ENSP00000346588.4
	MED23	ENST00000368060.7	TSL:1	c.3077T>G	p.Leu1026Arg	missense	Exon 23 of 30	ENSP00000357039.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461880 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727244

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112002

Other (OTH) AF: 0.00 AC: 0 AN: 60396

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.92	D
MetaSVM	Uncertain	0.42	D
MutationAssessor	Benign	1.6	L
PhyloP100		9.0
PrimateAI	Pathogenic	0.84	D
PROVEAN	Pathogenic	-4.5	D
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.77		Gain of methylation at L1026 (P = 0.0124)
MVP		0.88
MPC		2.7
ClinPred		1.0	D
GERP RS		6.2
Varity_R		0.93
gMVP		0.94
Mutation Taster		=5/95	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs1554253506; hg19: chr6-131915394;