rs121909188

Positions:

• chr7-19116946-C-A

Variant summary

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

The NM_000474.4(TWIST1):​c.376G>T​(p.Glu126*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,600 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TWIST1 NM_000474.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.77

Genes affected

TWIST1 (HGNC:12428): (twist family bHLH transcription factor 1) This gene encodes a basic helix-loop-helix (bHLH) transcription factor that plays an important role in embryonic development. The encoded protein forms both homodimers and heterodimers that bind to DNA E box sequences and regulate the transcription of genes involved in cranial suture closure during skull development. This protein may also regulate neural tube closure, limb development and brown fat metabolism. This gene is hypermethylated and overexpressed in multiple human cancers, and the encoded protein promotes tumor cell invasion and metastasis, as well as metastatic recurrence. Mutations in this gene cause Saethre-Chotzen syndrome in human patients, which is characterized by craniosynostosis, ptosis and hypertelorism. [provided by RefSeq, Jul 2020]

TWIST1 (HGNC:):

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 11 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-19116946-C-A is Pathogenic according to our data. Variant chr7-19116946-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 7977.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
TWIST1	NM_000474.4	c.376G>T	p.Glu126*	stop_gained	1/2	ENST00000242261.6	NP_000465.1
TWIST1	NR_149001.2	n.691G>T		non_coding_transcript_exon_variant	1/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TWIST1	ENST00000242261.6	c.376G>T	p.Glu126*	stop_gained	1/2	1	NM_000474.4	ENSP00000242261.5
TWIST1	ENST00000354571.5	n.172G>T		non_coding_transcript_exon_variant	1/3	2		ENSP00000346582.5
TWIST1	ENST00000443687.5	n.-24G>T		upstream_gene_variant		4		ENSP00000416986.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461600 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727128

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Saethre-Chotzen syndrome Pathogenic:2

Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 26, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	3billion	Mar 22, 2022	Stop-gained (nonsense): predicted to result in a loss or disruption of normal protein function through protein truncation. Multiple pathogenic variants are reported in the predicted truncated region.It is not observed in the gnomAD v2.1.1 dataset. The variant has been observed in multiple (>3) similarly affected unrelated individuals (PMID: 8988167, 24127277, 10649491, 19373776, 20643727). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Dec 21, 2023

Nonsense variant predicted to result in protein truncation, as the last 77 amino acids are lost, and other loss-of-function variants have been reported downstream in HGMD; Not observed in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 10649491, 11248247, 20643727, 19373776, 35591945, 24127277, 8988167) -

Saethre-Chotzen syndrome;C4551902:TWIST1-related craniosynostosis Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 12, 2023

ClinVar contains an entry for this variant (Variation ID: 7977). For these reasons, this variant has been classified as Pathogenic. This premature translational stop signal has been observed in individual(s) with Saethre-Chotzen syndrome (PMID: 8988167, 10649491, 19373776, 20643727, 24127277). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Glu126*) in the TWIST1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TWIST1 are known to be pathogenic (PMID: 10749989). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	45
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.88
FATHMM_MKL	Uncertain	0.97	D
Vest4		0.93
GERP RS		4.7

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: rs121909188; hg19: chr7-19156569;