7-19116976-G-C

Variant names:

• chr7-19116976-G-C
• rs1554442019
• NM_000474.4:c.346C>G

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_000474.4(TWIST1):​c.346C>G​(p.Arg116Gly) variant causes a missense change. 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. R116W) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TWIST1 NM_000474.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 3.77
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• Saethre-Chotzen syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, G2P, PanelApp Australia, Laboratory for Molecular Medicine, ClinGen, Orphanet, Labcorp Genetics (formerly Invitae)
• TWIST1-related craniosynostosis

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), ClinGen, Genomics England PanelApp
• isolated brachycephaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• isolated plagiocephaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• isolated scaphocephaly

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Sweeney-Cox syndrome

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 13 ACMG points.

• PM1: In a hotspot region, there are 11 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 11 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 chr7-19116976-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 3376165.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 31 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 1.057 (below the threshold of 3.09). Trascript score misZ: -0.22696 (below the threshold of 3.09). GenCC associations: The gene is linked to Saethre-Chotzen syndrome, Sweeney-Cox syndrome, isolated brachycephaly, TWIST1-related craniosynostosis, isolated plagiocephaly, isolated scaphocephaly.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.983
• PP5: Variant 7-19116976-G-C is Pathogenic according to our data. Variant chr7-19116976-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 543078.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TWIST1	NM_000474.4	c.346C>G	p.Arg116Gly	missense_variant	Exon 1 of 2	ENST00000242261.6	NP_000465.1
TWIST1	NR_149001.2	n.661C>G		non_coding_transcript_exon_variant	Exon 1 of 3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TWIST1	ENST00000242261.6	c.346C>G	p.Arg116Gly	missense_variant	Exon 1 of 2	1	NM_000474.4	ENSP00000242261.5
TWIST1	ENST00000354571.5	n.142C>G		non_coding_transcript_exon_variant	Exon 1 of 3	2		ENSP00000346582.5
TWIST1	ENST00000443687.5	n.-54C>G		upstream_gene_variant		4		ENSP00000416986.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Nov 16, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Different missense substitutions at this codon (p.Arg116Trp, p.Arg116Leu) have been reported in individuals affected with  Saethre-Chotzen syndrome (PMID: 9585583, 17693524) suggesting that this amino acid is critical for protein function. This sequence change replaces arginine with glycine at codon 116 of the TWIST1 protein (p.Arg116Gly). The arginine residue is highly conserved and there is a moderate physicochemical difference between arginine and glycine. This variant is not present in population databases (ExAC no frequency). This variant has been reported in an individual affected with Saethre-Chotzen syndrome (PMID: 15923834) and in an individual in the Leiden Open-source Variation Database (PMID: 21520333). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.89	D
M_CAP	Pathogenic	0.79	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.4	M
PhyloP100		3.8
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-6.8	D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0030	D
Vest4		0.99
ClinPred		0.98	D
GERP RS		4.7
Varity_R		0.96
gMVP		0.99
Mutation Taster		=4/96	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1554442019; hg19: chr7-19156599;