rs1554441995

Positions:

• chr7-19116927-C-G

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000474.4(TWIST1):​c.395G>C​(p.Arg132Pro) 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R132W) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TWIST1 NM_000474.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• 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 11 ACMG points.

• PM1: In a domain bHLH (size 51) in uniprot entity TWST1_HUMAN there are 15 pathogenic changes around while only 0 benign (100%) 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 chr7-19116928-G-A is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.989
• PP5: Variant 7-19116927-C-G is Pathogenic according to our data. Variant chr7-19116927-C-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 476634.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TWIST1	NM_000474.4	c.395G>C	p.Arg132Pro	missense_variant	1/2	ENST00000242261.6	NP_000465.1
TWIST1	NR_149001.2	n.710G>C		non_coding_transcript_exon_variant	1/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TWIST1	ENST00000242261.6	c.395G>C	p.Arg132Pro	missense_variant	1/2	1	NM_000474.4	ENSP00000242261.5
TWIST1	ENST00000354571.5	n.191G>C		non_coding_transcript_exon_variant	1/3	2		ENSP00000346582.5
TWIST1	ENST00000443687.5	n.-5G>C		upstream_gene_variant		4		ENSP00000416986.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 03, 2020

This variant has been observed in individual(s) with clinical features of Saethre-Chotzen syndrome (PMID: 9585583, Invitae). It has also been observed to segregate with disease in related individuals. For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Arg132 amino acid residue in TWIST1. Other variant(s) that disrupt this residue have been observed in individuals with TWIST1-related conditions (PMID: 25271085, 19373776), which suggests that this may be a clinically significant amino acid residue. 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. This variant is not present in population databases (ExAC no frequency). This sequence change replaces arginine with proline at codon 132 of the TWIST1 protein (p.Arg132Pro). The arginine residue is highly conserved and there is a moderate physicochemical difference between arginine and proline. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Sep 02, 2019

Not observed in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Reported in a family with Saethre-Chotzen syndrome, but familial segregation information and additional clinical information were not included (Paznekas et al., 1998); This variant is associated with the following publications: (PMID: 9585583) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	35
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.81	T
M_CAP	Pathogenic	0.83	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.8	H
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-7.0	D
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0070	D
Sift4G	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.87		Loss of MoRF binding (P = 0.014);
MVP		1.0
MPC		3.2
ClinPred		0.98	D
GERP RS		3.0
Varity_R		0.99
gMVP		1.0

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: rs1554441995; hg19: chr7-19156550;