12-49029400-C-T

Position:

• chr12-49029400-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_003482.4(KMT2D):​c.14075+1G>A variant causes a splice donor, 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 Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: KMT2D NM_003482.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.50

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 12-49029400-C-T is Pathogenic according to our data. Variant chr12-49029400-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 369674.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KMT2D	NM_003482.4	c.14075+1G>A		splice_donor_variant, intron_variant		ENST00000301067.12	NP_003473.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KMT2D	ENST00000301067.12	c.14075+1G>A		splice_donor_variant, intron_variant		5	NM_003482.4	ENSP00000301067.7

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Kabuki syndrome 1 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The splice donor c.14075+1G>A variant in the KMT2D gene has been observed in individual(s) with Kabuki syndrome (Dillon, Oliver James et al., 2018). The variant is absent in gnomAD Exomes. The variant has been submitted to ClinVar databse as Likely Pathogenic/Pathogenic. The variant affects the GT donor splice site downstream of exon 44. Loss of function variants have been previously reported to be disease causing. The spliceAI tool predicts the variant to be damaging. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Nov 24, 2014	This substitution is predicted to abolish the donor splice site of exon 43 and may result in premature truncation of the protein. This is a novel variant and is predicted to be deleterious by in-silico models. It was confirmed to be de novo in a child with clinical features of Kabuki syndrome. -

Kabuki syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 02, 2022

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 369674). Disruption of this splice site has been observed in individual(s) with Kabuki syndrome (PMID: 29453417; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change affects a donor splice site in intron 43 of the KMT2D gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in KMT2D are known to be pathogenic (PMID: 22126750). -

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

May 02, 2022

The c.14075+1G>A intronic variant results from a G to A substitution one nucleotide after coding exon 43 of the KMT2D gene. Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This alteration was reported in an infant with sensorineural hearing impairment, cleft palate, ventricular septal defect, and partially duplicated displaced kidney (Stark, 2016). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Based on the available evidence, this alteration is classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	0.99
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_DL_spliceai		1.0		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1057516039; hg19: chr12-49423183;