1-22659520-A-G

Variant names:

• chr1-22659520-A-G
• NM_001378156.1:c.58A>G

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001378156.1(C1QB):​c.58A>G​(p.Ile20Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. I20I) has been classified as Benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: C1QB NM_001378156.1 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -1.25

Genes affected

C1QB (HGNC:1242): (complement C1q B chain) This gene encodes the B-chain polypeptide of serum complement subcomponent C1q, which associates with C1r and C1s to yield the first component of the serum complement system. C1q is composed of 18 polypeptide chains which include 6 A-chains, 6 B-chains, and 6 C-chains. Each chain contains an N-terminal collagen-like region and a C-terminal C1q globular domain. C1q deficiency is associated with lupus erythematosus and glomerulonephritis. [provided by RefSeq, Dec 2016]

ENSG00000308848 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.09996155).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
C1QB	NM_001378156.1	c.58A>G	p.Ile20Val	missense_variant	Exon 2 of 3	ENST00000509305.6	NP_001365085.1
C1QB	NM_000491.5	c.64A>G	p.Ile22Val	missense_variant	Exon 2 of 3		NP_000482.3
C1QB	NM_001371184.3	c.58A>G	p.Ile20Val	missense_variant	Exon 3 of 4		NP_001358113.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
C1QB	ENST00000509305.6	c.58A>G	p.Ile20Val	missense_variant	Exon 2 of 3	1	NM_001378156.1	ENSP00000423689.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Nov 15, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.64A>G (p.I22V) alteration is located in exon 2 (coding exon 1) of the C1QB gene. This alteration results from a A to G substitution at nucleotide position 64, causing the isoleucine (I) at amino acid position 22 to be replaced by a valine (V). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.073
BayesDel_addAF	Benign	-0.12	T
BayesDel_noAF	Benign	-0.41
CADD	Benign	0.045
DANN	Benign	0.28
DEOGEN2	Benign	0.0085	.;T;T;T
Eigen	Benign	-1.6
Eigen_PC	Benign	-1.6
FATHMM_MKL	Benign	0.012	N
LIST_S2	Benign	0.27	T;T;T;T
M_CAP	Benign	0.026	D
MetaRNN	Benign	0.10	T;T;T;T
MetaSVM	Benign	-0.70	T
MutationAssessor	Benign	-0.31	.;.;.;N
PhyloP100		-1.3
PrimateAI	Benign	0.27	T
PROVEAN	Benign	-0.020	N;N;N;N
REVEL	Benign	0.17
Sift	Benign	0.27	T;T;T;T
Sift4G	Benign	0.46	T;T;T;T
Polyphen		0.0	.;.;.;B
Vest4		0.042, 0.040
MutPred		0.39		.;.;.;Loss of helix (P = 0.1299);
MVP		0.48
MPC		0.38
ClinPred		0.68	D
GERP RS		-3.8
Varity_R		0.024
gMVP		0.18
Mutation Taster		=98/2	polymorphism

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

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Other links and lift over

hg19: chr1-22986013;