chr12-49046631-T-TG

Position:

• chr12-49046631-T-TG

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.4395_4396insC​(p.Lys1466GlnfsTer25) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KMT2D NM_003482.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 1.83

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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 12-49046631-T-TG is Pathogenic according to our data. Variant chr12-49046631-T-TG is described in ClinVar as [Likely_pathogenic]. Clinvar id is 547421.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.4395_4396insC	p.Lys1466GlnfsTer25	frameshift_variant	16/55	ENST00000301067.12	NP_003473.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KMT2D	ENST00000301067.12	c.4395_4396insC	p.Lys1466GlnfsTer25	frameshift_variant	16/55	5	NM_003482.4	ENSP00000301067	A2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Kabuki syndrome 1 Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Medical Genetics Center, Maternal and Child Health Hospital of Hubei Province	Feb 01, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Laboratory of Medical Genetics, University of Torino	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Center for Human Genetics, Inc, Center for Human Genetics, Inc	Nov 01, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Dec 21, 2023	Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with Kabuki syndrome 1 (MIM#147920). The mechanism for branchial arch abnormalities, choanal atresia, athelia, hearing loss, and hypothyroidism syndrome (MIM#620186) is unclear, but is associated with variants in exons 38-39 (PMID: 31949313). (I) 0107 - This gene is associated with autosomal dominant disease. (I) 0115 - Variants in this gene are known to have variable expressivity in individuals with Kabuki syndrome (PMID: 21882399). (I) 0201 - Variant is predicted to cause nonsense-mediated decay (NMD) and loss of protein (premature termination codon is located at least 54 nucleotides upstream of the final exon-exon junction). (SP) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0701 - Other NMD predicted variants comparable to the one identified in this case have very strong previous evidence for pathogenicity (DECIPHER). (SP) 0802 - This variant has moderate previous evidence of pathogenicity in unrelated individuals. This variant has been classified as pathogenic or likely pathogenic by two clinical laboratories in ClinVar, and has been observed in one individual with Kabuki syndrome 1 in the literature (PMID: 25896430). (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1203 - This variant has been shown to be de novo in the proband (parental status confirmed) (by trio analysis). (SP) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Kabuki syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 18, 2019

This variant is not present in population databases (ExAC no frequency). For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in KMT2D are known to be pathogenic (PMID: 22126750). This variant has been observed in an individual with clinical features of Kabuki syndrome (PMID: 25896430). ClinVar contains an entry for this variant (Variation ID: 547421). This sequence change creates a premature translational stop signal (p.Lys1466Glnfs*25) in the KMT2D gene. It is expected to result in an absent or disrupted protein product. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Feb 05, 2024

Identified in patients with features of KMT2D-related Kabuki syndrome referred for genetic testing at GeneDx and in published literature (PMID: 25896430); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 25896430) -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1555195118; hg19: chr12-49440414;