chr12-49021874-T-C

Variant names:

• chr12-49021874-T-C
• NM_003482.4:c.16522-2A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_003482.4(KMT2D):​c.16522-2A>G variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: KMT2D NM_003482.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.93
• Publications: 0 publications found

Genes affected

KMT2D (HGNC:7133): (lysine methyltransferase 2D) The protein encoded by this gene is a histone methyltransferase that methylates the Lys-4 position of histone H3. The encoded protein is part of a large protein complex called ASCOM, which has been shown to be a transcriptional regulator of the beta-globin and estrogen receptor genes. Mutations in this gene have been shown to be a cause of Kabuki syndrome. [provided by RefSeq, Oct 2010]

KMT2D Gene-Disease associations (from GenCC):

• choanal atresia-athelia-hypothyroidism-delayed puberty-short stature syndrome

  Inheritance: AD Classification: DEFINITIVE, MODERATE Submitted by: Illumina, G2P
• Kabuki syndrome 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Laboratory for Molecular Medicine, ClinGen, Labcorp Genetics (formerly Invitae), Ambry Genetics
• branchial arch abnormalities, choanal atresia, athelia, hearing loss, and hypothyroidism syndrome

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• Kabuki syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000288710 (HGNC:):

ACMG classification

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

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.17425063 fraction of the gene.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 12-49021874-T-C is Pathogenic according to our data. Variant chr12-49021874-T-C is described in ClinVar as [Pathogenic]. Clinvar id is 2088162.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KMT2D	NM_003482.4	c.16522-2A>G		splice_acceptor_variant, intron_variant	Intron 54 of 54	ENST00000301067.12	NP_003473.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KMT2D	ENST00000301067.12	c.16522-2A>G		splice_acceptor_variant, intron_variant	Intron 54 of 54	5	NM_003482.4	ENSP00000301067.7
ENSG00000288710	ENST00000683988.1	n.493-2A>G		splice_acceptor_variant, intron_variant	Intron 4 of 15			ENSP00000506939.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Kabuki syndrome Pathogenic:1

Sep 02, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. Disruption of this splice site has been observed in individual(s) with clinical features of Kabuki syndrome (Invitae). In at least one individual the variant was observed to be de novo. This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 53 of the KMT2D gene. While this variant is not anticipated to result in nonsense mediated decay, it likely alters RNA splicing and results in a disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.020
CADD	Pathogenic	34
DANN	Uncertain	0.98
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		7.9
GERP RS		4.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Mutation Taster		=13/87	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.43		Position offset: -20
DS_AL_spliceai		0.99		Position offset: -2

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

Other links and lift over

hg19: chr12-49415657;