chr7-19116856-T-C

Position:

• chr7-19116856-T-C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000474.4(TWIST1):​c.466A>G​(p.Ile156Val) variant causes a missense 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. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I156S) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TWIST1 NM_000474.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.88

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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_000474.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-19116855-A-C is described in ClinVar as [Pathogenic]. Clinvar id is 1455499.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973
• PP5: Variant 7-19116856-T-C is Pathogenic according to our data. Variant chr7-19116856-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 7982.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TWIST1	NM_000474.4	c.466A>G	p.Ile156Val	missense_variant	1/2	ENST00000242261.6
TWIST1	NR_149001.2	n.781A>G		non_coding_transcript_exon_variant	1/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TWIST1	ENST00000242261.6	c.466A>G	p.Ile156Val	missense_variant	1/2	1	NM_000474.4	P1
TWIST1	ENST00000354571.5	c.265A>G	p.Ile89Val	missense_variant, NMD_transcript_variant	1/3	2
TWIST1	ENST00000443687.5	c.70A>G	p.Ile24Val	missense_variant, NMD_transcript_variant	1/4	4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Saethre-Chotzen syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Department of Medical Genetics, Oslo University Hospital	-	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Dec 15, 2001	- -

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

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 01, 2022

Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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. This variant disrupts the p.Ile156 amino acid residue in TWIST1. Other variant(s) that disrupt this residue have been determined to be pathogenic (Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. ClinVar contains an entry for this variant (Variation ID: 7982). This missense change has been observed in individual(s) with TWIST1-related conditions (PMID: 11754069, 31754721). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 156 of the TWIST1 protein (p.Ile156Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.38
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.92	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	2.9	M
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.84	D
PROVEAN	Benign	-1.0	N
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0060	D
Polyphen		1.0	D
Vest4		0.92
MutPred		0.80		Gain of MoRF binding (P = 0.1613);
MVP		1.0
MPC		2.4
ClinPred		0.98	D
GERP RS		4.8
Varity_R		0.69
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.31		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.31		Position offset: 5

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

Publications

LitVar

Other links and lift over

dbSNP: rs104894059; hg19: chr7-19156479;