rs199856844

Positions:

• chr2-38995147-C-G
• chr2-38995147-C-T

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4 BS2

The NM_005633.4(SOS1):​c.3322G>C​(p.Asp1108His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000267 in 1,461,638 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000027 (0 hom.)
• Consequence: SOS1 NM_005633.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:1
• Conservation: PhyloP100: 7.21

Genes affected

SOS1 (HGNC:11187): (SOS Ras/Rac guanine nucleotide exchange factor 1) This gene encodes a protein that is a guanine nucleotide exchange factor for RAS proteins, membrane proteins that bind guanine nucleotides and participate in signal transduction pathways. GTP binding activates and GTP hydrolysis inactivates RAS proteins. The product of this gene may regulate RAS proteins by facilitating the exchange of GTP for GDP. Mutations in this gene are associated with gingival fibromatosis 1 and Noonan syndrome type 4. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_benign. Variant got -5 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.30417097).
• BS2: High AC in GnomAdExome4 at 39 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SOS1	NM_005633.4	c.3322G>C	p.Asp1108His	missense_variant	20/23	ENST00000402219.8	NP_005624.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SOS1	ENST00000402219.8	c.3322G>C	p.Asp1108His	missense_variant	20/23	1	NM_005633.4	ENSP00000384675.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250752 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135530

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000884

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000267 AC: 39 AN: 1461638 Hom.: 0 Cov.: 31 AF XY: 0.0000179 AC XY: 13 AN XY: 727124

Gnomad4 AFR exome AF: 0.0000299

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: 0.0000333

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Sep 10, 2018	See Variant Classification Assertion Criteria. -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	May 30, 2016	Variant summary: The SOS1 c.3322G>C (p.Asp1108His) variant involves the alteration of a higly conserved nucleotide. 3/5 in silico tools predict a damaging outcome. This variant was found in 1/121266 control chromosomes at a frequency of 0.0000082, which does not exceed the estimated maximal expected allele frequency of a pathogenic SOS1 variant (0.00003). The variant of interest is located outside of any known functional domains and has not, to our knowledge, been reported in affected individuals via publications and/or reputable databases/clinical diagnostic laboratories, nor evaluated for functional impact by in vivo/vitro studies. Due to the absence of clinical information and lack of functional studies, the variant is currently classified as a variant of uncertain significance (VUS) until additional information becomes available. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 20, 2023

The p.D1108H variant (also known as c.3322G>C), located in coding exon 20 of the SOS1 gene, results from a G to C substitution at nucleotide position 3322. The aspartic acid at codon 1108 is replaced by histidine, an amino acid with similar properties. This alteration was reported in a prenatal subject with cystic hygroma (Leach NT et al. Genet Med, 2019 Feb;21:417-425). This amino acid position is well conserved in available 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. -

RASopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 13, 2022

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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 496304). This missense change has been observed in individual(s) with clinical features of SOS1-related conditions (PMID: 29907801). This variant is present in population databases (rs199856844, gnomAD 0.0009%). This sequence change replaces aspartic acid, which is acidic and polar, with histidine, which is basic and polar, at codon 1108 of the SOS1 protein (p.Asp1108His). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Uncertain	0.023	T
BayesDel_noAF	Benign	-0.20
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.42	T;T;T
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.85	.;T;T
M_CAP	Benign	0.029	D
MetaRNN	Benign	0.30	T;T;T
MetaSVM	Benign	-0.47	T
MutationAssessor	Benign	1.7	L;L;.
PrimateAI	Pathogenic	0.79	T
PROVEAN	Benign	-1.2	N;N;N
REVEL	Benign	0.27
Sift	Uncertain	0.022	D;D;D
Sift4G	Benign	0.10	T;T;T
Polyphen		0.80	P;P;.
Vest4		0.47
MutPred		0.19		Loss of sheet (P = 0.0315);Loss of sheet (P = 0.0315);Loss of sheet (P = 0.0315);
MVP		0.52
MPC		0.42
ClinPred		0.73	D
GERP RS		5.0
Varity_R		0.11
gMVP		0.43

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.10		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: rs199856844; hg19: chr2-39222288;