1-2228774-C-T

Position:

• chr1-2228774-C-T

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_Moderate BS2

The NM_003036.4(SKI):​c.8C>T​(p.Ala3Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000133 in 1,129,918 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A3E) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.000013 (0 hom.)
• Consequence: SKI NM_003036.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 1.51

Genes affected

SKI (HGNC:10896): (SKI proto-oncogene) This gene encodes the nuclear protooncogene protein homolog of avian sarcoma viral (v-ski) oncogene. It functions as a repressor of TGF-beta signaling, and may play a role in neural tube development and muscle differentiation. [provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Likely_benign. Variant got -6 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.2093795).
• BS2: High AC in GnomAdExome4 at 15 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SKI	NM_003036.4	c.8C>T	p.Ala3Val	missense_variant	1/7	ENST00000378536.5
SKI	XM_005244775.4	c.8C>T	p.Ala3Val	missense_variant	1/7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SKI	ENST00000378536.5	c.8C>T	p.Ala3Val	missense_variant	1/7	1	NM_003036.4	P1
SKI	ENST00000704337.1	n.137+1250C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.0000133 AC: 15 AN: 1129918 Hom.: 0 Cov.: 31 AF XY: 0.0000126 AC XY: 7 AN XY: 553578

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000140

Gnomad4 OTH exome AF: 0.0000472

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 16, 2023

The p.A3V variant (also known as c.8C>T), located in coding exon 1 of the SKI gene, results from a C to T substitution at nucleotide position 8. The alanine at codon 3 is replaced by valine, an amino acid with similar properties. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 2574 samples (5148 alleles) with coverage at this position. This amino acid position is poorly conserved on very limited sequence alignment, and valine is the reference amino acid in other vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Feb 13, 2023

Has not been previously published as pathogenic or benign to our knowledge; Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function -

Shprintzen-Goldberg syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 17, 2023

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 3 of the SKI protein (p.Ala3Val). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SKI-related conditions. ClinVar contains an entry for this variant (Variation ID: 520156). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SKI protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.30
BayesDel_addAF	Uncertain	0.040	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	23
DANN	Benign	0.97
DEOGEN2	Benign	0.26	T
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.13	N
LIST_S2	Benign	0.59	T
M_CAP	Pathogenic	0.98	D
MetaRNN	Benign	0.21	T
MetaSVM	Benign	-0.29	T
MutationAssessor	Benign	0.34	N
MutationTaster	Benign	1.0	N
PrimateAI	Pathogenic	0.85	D
PROVEAN	Benign	-0.95	N
REVEL	Benign	0.24
Sift	Benign	0.041	D
Sift4G	Benign	0.17	T
Polyphen		0.0	B
Vest4		0.18
MutPred		0.29		Gain of sheet (P = 0.0061);
MVP		0.80
MPC		1.5
ClinPred		0.14	T
RBP_binding_hub_radar		1.1
RBP_regulation_power_radar		4.0
Varity_R		0.093
gMVP		0.35

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: rs1553189801; hg19: chr1-2160213;