7-19117047-CCGCCGCCGCCGCCCG-CCGCCGCCGCCGCCCGCGCCGCCGCCGCCCGCGCCGCCGCCGCCCG

Variant names:

• chr7-19117047-C-CCGCCGCCGCCGCCCGCGCCGCCGCCGCCCG
• rs760471055
• NM_000474.4:c.274_275insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM1

The NM_000474.4(TWIST1):​c.274_275insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG​(p.Gly91_Gly92insAlaGlyGlyGlyGlyAlaGlyGlyGlyGly) variant causes a conservative inframe insertion change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type INS_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TWIST1 NM_000474.4 conservative_inframe_insertion
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.351
• 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: Uncertain_significance. The variant received 2 ACMG points.

• PM1: In a chain Twist-related protein 1 (size 201) in uniprot entity TWST1_HUMAN there are 39 pathogenic changes around while only 6 benign (87%) in NM_000474.4

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TWIST1	NM_000474.4	c.274_275insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG	p.Gly91_Gly92insAlaGlyGlyGlyGlyAlaGlyGlyGlyGly	conservative_inframe_insertion	Exon 1 of 2	ENST00000242261.6	NP_000465.1
TWIST1	NR_149001.2	n.589_590insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG		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.274_275insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG	p.Gly91_Gly92insAlaGlyGlyGlyGlyAlaGlyGlyGlyGly	conservative_inframe_insertion	Exon 1 of 2	1	NM_000474.4	ENSP00000242261.5
TWIST1	ENST00000354571.5	n.70_71insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG		non_coding_transcript_exon_variant	Exon 1 of 3	2		ENSP00000346582.5
TWIST1	ENST00000443687.5	n.-126_-125insCGGGCGGCGGCGGCGCGGGCGGCGGCGGCG		upstream_gene_variant		4		ENSP00000416986.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.35

Splicing

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

Other links and lift over

dbSNP: rs760471055; hg19: chr7-19156670;