chr10-110598286-C-G

Position:

• chr10-110598286-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP2

The NM_005445.4(SMC3):​c.2264C>G​(p.Pro755Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SMC3 NM_005445.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.45

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 Uncertain_significance. Variant got 3 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMC3	NM_005445.4	c.2264C>G	p.Pro755Arg	missense_variant	20/29	ENST00000361804.5	NP_005436.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMC3	ENST00000361804.5	c.2264C>G	p.Pro755Arg	missense_variant	20/29	1	NM_005445.4	ENSP00000354720.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1461292 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726986

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cornelia de Lange syndrome 3 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 14, 2024

This sequence change replaces proline, which is neutral and non-polar, with arginine, which is basic and polar, at codon 755 of the SMC3 protein (p.Pro755Arg). 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. Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt SMC3 protein function with a negative 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	0.95
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Benign	0.33	T
Eigen	Uncertain	0.64
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D
M_CAP	Benign	0.062	D
MetaRNN	Uncertain	0.72	D
MetaSVM	Benign	-0.37	T
MutationAssessor	Benign	0.86	L
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-4.7	D
REVEL	Uncertain	0.54
Sift	Uncertain	0.011	D
Sift4G	Uncertain	0.060	T
Polyphen		0.99	D
Vest4		0.78
MutPred		0.42		Gain of MoRF binding (P = 0.0057);
MVP		0.81
MPC		1.3
ClinPred		0.97	D
GERP RS		5.5
Varity_R		0.61
gMVP		0.57

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs76568464; hg19: chr10-112358044;