7-107661643-T-C

Variant summary

Our verdict is Pathogenic. Variant got 20 ACMG points: 20P and 0B. PVS1 PS1_Moderate PM2 PP5_Very_Strong

The NM_000441.2(SLC26A4):c.2T>C(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000145 in 1,562,624 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000079 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00015 (0 hom.)
• Consequence: SLC26A4 NM_000441.2 start_lost
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:16
• Conservation: PhyloP100: 2.90

Genes affected

SLC26A4 (HGNC:8818): (solute carrier family 26 member 4) Mutations in this gene are associated with Pendred syndrome, the most common form of syndromic deafness, an autosomal-recessive disease. It is highly homologous to the SLC26A3 gene; they have similar genomic structures and this gene is located 3' of the SLC26A3 gene. The encoded protein has homology to sulfate transporters. [provided by RefSeq, Jul 2008]

SLC26A4-AS1 (HGNC:22385): (SLC26A4 antisense RNA 1)

ACMG classification

Verdict is Pathogenic. Variant got 20 ACMG points.

• PVS1: Start lost variant, no new inframe start found.
• PS1: Another start lost variant in NM_000441.2 (SLC26A4) was described as [Pathogenic] in ClinVar as 1185667
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-107661643-T-C is Pathogenic according to our data. Variant chr7-107661643-T-C is described in ClinVar as [Pathogenic]. Clinvar id is 43553.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr7-107661643-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SLC26A4	NM_000441.2	c.2T>C	p.Met1?	start_lost	2/21	ENST00000644269.2
SLC26A4-AS1	NR_028137.1	n.156A>G		non_coding_transcript_exon_variant	1/2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SLC26A4	ENST00000644269.2	c.2T>C	p.Met1?	start_lost	2/21		NM_000441.2	P1
SLC26A4-AS1	ENST00000668981.1	n.216A>G		non_coding_transcript_exon_variant	1/2

Frequencies

GnomAD3 genomes AF: 0.0000788 AC: 12 AN: 152258 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000482

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000694 AC: 12 AN: 172798 Hom.: 0 AF XY: 0.0000846 AC XY: 8 AN XY: 94532

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000159

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000152 AC: 214 AN: 1410366 Hom.: 0 Cov.: 30 AF XY: 0.000129 AC XY: 90 AN XY: 698144

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000260

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000265

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000190

Gnomad4 OTH exome AF: 0.0000850

GnomAD4 genome AF: 0.0000788 AC: 12 AN: 152258 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74394

Gnomad4 AFR AF: 0.0000482

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000150 Hom.: 0

Bravo AF: 0.0000907

ExAC AF: 0.0000260 AC: 3

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:16

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 30, 2024	This sequence change affects the initiator methionine of the SLC26A4 mRNA. The next in-frame methionine is located at codon 21. This variant is present in population databases (rs111033302, gnomAD 0.02%). Disruption of the initiator codon has been observed in individual(s) with nonsyndromic sensorineural hearing loss and enlargement of vestibular aqueduct (PMID: 19204907, 19509082, 21961810, 23965030, 25372295, 27997596). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 43553). Algorithms developed to predict the effect of variants on protein structure and function are not available or were not evaluated for this variant. Experimental studies have shown that disruption of the initiator codon affects SLC26A4 function (PMID: 19204907). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jun 07, 2021	- -
Pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Aug 31, 2023	Published functional studies demonstrate that variant results in protein retention in the endoplasmic reticulum (Choi et al., 2009); This variant is associated with the following publications: (PMID: 27997596, 25372295, 19509082, 20128824, 15099345, 14679580, 24224479, 28780564, 21961810, 16950989, 23965030, 21704276, 19204907, 31589614, 34062854) -

Pendred syndrome Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 06, 2023	Variant summary: SLC26A4 c.2T>C (p.Met1Thr) alters the initiation codon and is predicted to result either in absence of the protein or truncation of the encoded protein due to translation initiation at a downstream codon. Two of three in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 6.9e-05 in 172798 control chromosomes. This frequency is not significantly higher than expected for a pathogenic variant in SLC26A4 causing Pendred Syndrome (6.9e-05 vs 0.0035), allowing no conclusion about variant significance. c.2T>C has been reported in the literature in individuals affected with Enlargement of the Vestibular aqueduct and Hearing loss, usually associated with Pendred Syndrome( Example: Alber_2006, Choi_2009, Siem_2010, Sloan-Heggen_2016, Smits_2022, Gardner_2006 etc). These data indicate that the variant is likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function (Choi_2009) indicating the protein was retained within the endoplasmic reticulum with no surface expression. Nine clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 11, 2019	This variant was determined to be pathogenic according to ACMG Guidelines, 2015 [PMID:25741868]. This variant has been previously reported as pathogenic [PMID 14679580, 19204907, 21961810, 24224479] -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -

Autosomal recessive nonsyndromic hearing loss 4 Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Johns Hopkins Genomics, Johns Hopkins University	Jun 21, 2023	This SLC26A4 variant (rs111033302) is rare (<0.1%) in a large population dataset (gnomAD: 16/204190 total alleles; MAF 0.008%; no homozygotes) and has been reported in ClinVar. This variant alters the initiation codon and is predicted to result either in absence of the protein or alteration of the encoded protein due to translation initiation at a downstream methionine codon. In vitro functional studies of p.Met1Thr using transfected cells showed the protein was retained within the endoplasmic reticulum with no surface expression. This SLC26A4 variant has been reported in unrelated individuals with hearing loss and EVA, usually in a compound heterozygous state with a different pathogenic variant. We consider c.2T>C (p.Met1Thr) to be pathogenic for DFNB4. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Jan 03, 2020	This variant was determined to be pathogenic according to ACMG Guidelines, 2015 [PMID:25741868]. -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Neurogenetic Laboratory, Second Faculty of Medicine, Charles University	Mar 30, 2021	- -

SLC26A4-related disorder Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	Jan 19, 2023	The SLC26A4 c.2T>C variant is predicted to disrupt the translation initiation site (Start Loss). This variant has been reported in individuals with autosomal recessive Pendred syndrome or nonsyndromic enlarged vestibular aqueduct (NSEVA) (reported as "M1T" in Prasad et al. 2004. PubMed ID: 14679580; Choi et al. 2009. PubMed ID: 19204907; Ladsous et al. 2014. PubMed ID: 24224479). This variant is reported in 0.015% of alleles in individuals of European (Non-Finnish) descent in gnomAD (http://gnomad.broadinstitute.org/variant/7-107302088-T-C). This variant has been classified as pathogenic by multiple independent submitters to the ClinVar database (https://www.ncbi.nlm.nih.gov/clinvar/variation/43553). Given all the evidence, we interpret c.2T>C (p.Met1?) as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center	Oct 03, 2022	PVS1_Strong, PS3, PM3_Strong -

Rare genetic deafness Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Nov 22, 2017

The c.2T>C (p.Met1?) variant in SLC26A4 has been reported in at least 6 individu als with hearing loss and EVA, all of whom were compound heterozygous (Shears 20 04, Gardner 2006, Dai 2009, Choi 2009, Huang 2011, Ladsous 2014, LMM data). It h as been identified in 0.01% (14/87438) of European chromosomes by the Genome Agg regation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs111033302). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a carrier frequency for recessive hearing loss . This variant affects the translation initiation start codon (ATG) and is there fore predicted to disrupt translation. In vitro functional studies provide some evidence that the c.2T>C variant may impact protein function (Choi 2009). Additi onally, a different variant in the translation initiation start codon (c.3G>C) h as also been reported in an individual with hearing loss and EVA, supporting tha t changes to this codon are not tolerated. In summary, this variant meets crite ria to be classified as pathogenic for hearing loss in an autosomal recessive ma nner based on the predicted impact of the variant and multiple occurrences with pathogenic SLC26A4 variants in individuals with hearing loss. ACMG/AMP Criteria applied: PVS1; PM3_VeryStrong; PP4. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.38
Cadd	Benign	23
Dann	Benign	0.95
DEOGEN2	Benign	0.15	T;T;T
Eigen	Benign	-0.20
Eigen_PC	Benign	-0.13
FATHMM_MKL	Benign	0.73	D
M_CAP	Pathogenic	0.95	D
MetaRNN	Uncertain	0.65	D;D;D
MetaSVM	Uncertain	0.23	D
MutationTaster	Benign	0.97	D
PROVEAN	Benign	-1.2	N;.;N
REVEL	Uncertain	0.62
Sift	Uncertain	0.0080	D;.;D
Sift4G	Pathogenic	0.0	D;.;D
Polyphen		0.089	B;B;.
Vest4		0.94
MVP		0.97
ClinPred		0.58	D
GERP RS		3.8
Varity_R		0.56
gMVP		0.57

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: rs111033302; hg19: chr7-107302088;