rs121909186

Positions:

• chr7-19117013-G-GT

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000474.4(TWIST1):​c.308dupA​(p.Tyr103fs) variant causes a frameshift, stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TWIST1 NM_000474.4 frameshift, stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.513

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 12 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 21 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-19117013-G-GT is Pathogenic according to our data. Variant chr7-19117013-G-GT is described in ClinVar as [Pathogenic]. Clinvar id is 7973.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TWIST1	NM_000474.4	c.308dupA	p.Tyr103fs	frameshift_variant, stop_gained	1/2	ENST00000242261.6	NP_000465.1
TWIST1	NR_149001.2	n.623dupA		non_coding_transcript_exon_variant	1/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TWIST1	ENST00000242261.6	c.308dupA	p.Tyr103fs	frameshift_variant, stop_gained	1/2	1	NM_000474.4	ENSP00000242261.5
TWIST1	ENST00000354571.5	n.104dupA		non_coding_transcript_exon_variant	1/3	2		ENSP00000346582.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 22, 2024

The c.308dupA (p.Y103*) alteration, located in exon 1 (coding exon 1) of the TWIST1 gene, consists of a duplication of A at position 308. This changes the amino acid from a tyrosine (Y) to a stop codon at amino acid position 103. This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). Based on the available evidence, this alteration is classified as pathogenic. -

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 24, 2022

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 7973). This premature translational stop signal has been observed in individual(s) with Saethre-Chotzen syndrome (PMID: 8988166). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Tyr103*) 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). -

Saethre-Chotzen syndrome Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jan 01, 1997

- -

Computational scores

Source: dbNSFP v4.3

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: rs121909186; hg19: chr7-19156636;