3-69959370-C-T

Position:

• chr3-69959370-C-T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_001354604.2(MITF):​c.1129C>T​(p.Arg377Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R377R) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MITF NM_001354604.2 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 2.45

Genes affected

MITF (HGNC:7105): (melanocyte inducing transcription factor) The protein encoded by this gene is a transcription factor that contains both basic helix-loop-helix and leucine zipper structural features. The encoded protein regulates melanocyte development and is responsible for pigment cell-specific transcription of the melanogenesis enzyme genes. Heterozygous mutations in the this gene cause auditory-pigmentary syndromes, such as Waardenburg syndrome type 2 and Tietz syndrome. [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. There are 18 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-69959370-C-T is Pathogenic according to our data. Variant chr3-69959370-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 228363.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MITF	NM_001354604.2	c.1129C>T	p.Arg377Ter	stop_gained	9/10	ENST00000352241.9
MITF	NM_000248.4	c.808C>T	p.Arg270Ter	stop_gained	8/9	ENST00000394351.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MITF	ENST00000352241.9	c.1129C>T	p.Arg377Ter	stop_gained	9/10	1	NM_001354604.2	P4
MITF	ENST00000394351.9	c.808C>T	p.Arg270Ter	stop_gained	8/9	1	NM_000248.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Oct 31, 2023

Nonsense variant in the C-terminus predicted to result in protein truncation, as the last 150 amino acids are lost, and other loss-of-function variants have been reported downstream in the Human Gene Mutation Database (HGMD); Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 34142234, 27759048) -

Waardenburg syndrome type 2A Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Genetic Testing Center for Deafness, Department of Otolaryngology Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital

Jan 01, 2019

- -

Rare genetic deafness Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Jan 12, 2016

The p.Arg371X variant in MITF has been identified by our laboratory in one indiv idual with hearing loss, which is assumed to have occurred de novo. It has not been reported in large population studies. This nonsense variant leads to a pr emature termination codon at position 371 and is located 51 nucleotides from the end of the penultimate (second to last) exon. Therefore, this variant is expect ed to undergo nonsense mediated mRNA decay (NMD) (Holbrook 2004) resulting in a n absent protein. However, due to its close location to the penultimate intron it could escape NMD and leading to a truncated protein. Heterozygous loss of fu nction variants in the MITF gene are well described in individuals with Waardenb urg syndrome. In summary, the p.Arg371X variant meets the criteria to be classi fied as pathogenic for hearing loss in an autosomal dominant manner. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	37
DANN	Uncertain	1.0
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Uncertain	0.87	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D
Vest4		0.98
GERP RS		3.0

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

LitVar

Other links and lift over

dbSNP: rs876657699; hg19: chr3-70008521; COSMIC: COSV58833666;