Genetic Variant KMT2A:p.Arg24AlafsTer123 (chr11-118436575-C-CG) – ACMG Classification: Likely_pathogenic (8 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1

The NM_001197104.2(KMT2A):c.69dupG(p.Arg24AlafsTer123) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000693 in 1,009,408 control chromosomes in the GnomAD database, with no homozygous occurrence. There is a variant allele frequency bias in the population database for this variant (GnomAdExome4), which may indicate mosaicism or somatic mutations in the reference population data. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000069 ( 0 hom. )

Consequence

KMT2A
NM_001197104.2 frameshift

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.289

Publications

0 publications found

Variant links:

Genes affected

KMT2A (HGNC:7132): (lysine methyltransferase 2A) This gene encodes a transcriptional coactivator that plays an essential role in regulating gene expression during early development and hematopoiesis. The encoded protein contains multiple conserved functional domains. One of these domains, the SET domain, is responsible for its histone H3 lysine 4 (H3K4) methyltransferase activity which mediates chromatin modifications associated with epigenetic transcriptional activation. This protein is processed by the enzyme Taspase 1 into two fragments, MLL-C and MLL-N. These fragments reassociate and further assemble into different multiprotein complexes that regulate the transcription of specific target genes, including many of the HOX genes. Multiple chromosomal translocations involving this gene are the cause of certain acute lymphoid leukemias and acute myeloid leukemias. Alternate splicing results in multiple transcript variants.[provided by RefSeq, Oct 2010]

KMT2A Gene-Disease associations (from GenCC):

Wiedemann-Steiner syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Illumina, Labcorp Genetics (formerly Invitae), ClinGen

KMT2A links:

ENSG00000285827 (HGNC:):

ENSG00000285827 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 448 pathogenic variants in the truncated region.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KMT2A	NM_001197104.2 link	c.69dupG	p.Arg24AlafsTer123	frameshift_variant	Exon 1 of 36	ENST00000534358.8	NP_001184033.1	Q03164-3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KMT2A	ENST00000534358.8 link	c.69dupG	p.Arg24AlafsTer123	frameshift_variant	Exon 1 of 36	1	NM_001197104.2	ENSP00000436786.2		Q03164-3
ENSG00000285827	ENST00000648261.1 link	c.-798-32194dupG		intron_variant	Intron 1 of 6			ENSP00000498126.1		A0A3B3ITZ1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000693

AC:

AN:

1009408

Hom.:

Cov.:

AF XY:

0.00000839

AC XY:

AN XY:

476576

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

20692

American (AMR)

AF:

0.000150

AC:

AN:

6680

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

11916

East Asian (EAS)

AF:

0.0000446

AC:

AN:

22400

South Asian (SAS)

AF:

0.00

AC:

AN:

18598

European-Finnish (FIN)

AF:

0.00

AC:

AN:

26710

Middle Eastern (MID)

AF:

0.00

AC:

AN:

2892

European-Non Finnish (NFE)

AF:

0.00000581

AC:

AN:

860480

Other (OTH)

AF:

0.00

AC:

AN:

39040

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.225

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

-0.29

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

Publications

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11-118436575-C-CG

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over