rs1556890616

chrX-53412188-T-C

Variant summary

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

The NM_006306.4(SMC1A):c.920A>G(p.His307Arg) 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: 23)
• Consequence: SMC1A NM_006306.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.75

Genes affected

SMC1A (HGNC:11111): (structural maintenance of chromosomes 1A) Proper cohesion of sister chromatids is a prerequisite for the correct segregation of chromosomes during cell division. The cohesin multiprotein complex is required for sister chromatid cohesion. This complex is composed partly of two structural maintenance of chromosomes (SMC) proteins, SMC3 and either SMC1B or the protein encoded by this gene. Most of the cohesin complexes dissociate from the chromosomes before mitosis, although those complexes at the kinetochore remain. Therefore, the encoded protein is thought to be an important part of functional kinetochores. In addition, this protein interacts with BRCA1 and is phosphorylated by ATM, indicating a potential role for this protein in DNA repair. This gene, which belongs to the SMC gene family, is located in an area of the X-chromosome that escapes X inactivation. Mutations in this gene result in Cornelia de Lange syndrome. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, SMC1A

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMC1A	NM_006306.4	c.920A>G	p.His307Arg	missense_variant	6/25	ENST00000322213.9
SMC1A	NM_001281463.1	c.854A>G	p.His285Arg	missense_variant	7/26

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMC1A	ENST00000322213.9	c.920A>G	p.His307Arg	missense_variant	6/25	1	NM_006306.4	P1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 23

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital muscular hypertrophy-cerebral syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 18, 2016

This sequence change replaces histidine with arginine at codon 307 of the SMC1A protein (p.His307Arg). The histidine residue is highly conserved and there is a small physicochemical difference between histidine and arginine. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a SMC1A-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
Cadd	Uncertain	24
Dann	Uncertain	0.99
DEOGEN2	Uncertain	0.49	T;T
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.95	D;D
M_CAP	Uncertain	0.26	D
MetaRNN	Uncertain	0.73	D;D
MetaSVM	Uncertain	0.12	D
MutationAssessor	Benign	1.5	L;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-7.4	D;.
REVEL	Pathogenic	0.70
Sift	Uncertain	0.0020	D;.
Sift4G	Uncertain	0.0060	D;D
Polyphen		1.0	D;.
Vest4		0.58
MutPred		0.44		Gain of glycosylation at S306 (P = 0.0677);.;
MVP		0.95
MPC		3.1
ClinPred		1.0	D
GERP RS		4.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.94
gMVP		0.94

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: rs1556890616; hg19: chrX-53439138;