10-110601122-G-C

Variant names:

• chr10-110601122-G-C
• rs797045996
• NM_005445.4:c.2636G>C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP2 PP3_Moderate PP5

The NM_005445.4(SMC3):​c.2636G>C​(p.Arg879Pro) 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. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMC3 NM_005445.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 9.53

Genes affected

SMC3 (HGNC:2468): (structural maintenance of chromosomes 3) This gene belongs to the SMC3 subfamily of SMC proteins. The encoded protein occurs in certain cell types as either an intracellular, nuclear protein or a secreted protein. The nuclear form, known as structural maintenance of chromosomes 3, is a component of the multimeric cohesin complex that holds together sister chromatids during mitosis, enabling proper chromosome segregation. Post-translational modification of the encoded protein by the addition of chondroitin sulfate chains gives rise to the secreted proteoglycan bamacan, an abundant basement membrane protein. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the SMC3 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 44 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. Gene score misZ: 6.3999 (above the threshold of 3.09). Trascript score misZ: 7.6232 (above the threshold of 3.09). GenCC associations: The gene is linked to Cornelia de Lange syndrome, Cornelia de Lange syndrome 3.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.842
• PP5: Variant 10-110601122-G-C is Pathogenic according to our data. Variant chr10-110601122-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 212272.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMC3	NM_005445.4	c.2636G>C	p.Arg879Pro	missense_variant	Exon 23 of 29	ENST00000361804.5	NP_005436.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMC3	ENST00000361804.5	c.2636G>C	p.Arg879Pro	missense_variant	Exon 23 of 29	1	NM_005445.4	ENSP00000354720.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cornelia de Lange syndrome 3 Pathogenic:1 Uncertain:1

Mar 30, 2015

Genetic Services Laboratory, University of Chicago

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 27, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 879 of the SMC3 protein (p.Arg879Pro). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SMC3-related conditions. ClinVar contains an entry for this variant (Variation ID: 212272). 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 expected to disrupt SMC3 protein function with a positive predictive value of 80%. 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	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.49	T
Eigen	Pathogenic	0.72
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.84	D
MetaSVM	Uncertain	-0.038	T
MutationAssessor	Benign	1.6	L
PrimateAI	Uncertain	0.79	T
PROVEAN	Uncertain	-3.1	D
REVEL	Pathogenic	0.74
Sift	Benign	0.12	T
Sift4G	Benign	0.14	T
Polyphen		0.99	D
Vest4		0.80
MutPred		0.68		Loss of MoRF binding (P = 0.0053);
MVP		0.81
MPC		2.3
ClinPred		0.98	D
GERP RS		5.3
Varity_R		0.68
gMVP		0.97

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: rs797045996; hg19: chr10-112360880;