1-22659644-G-C

Variant names:

• chr1-22659644-G-C
• rs1361922961
• NM_001378156.1:c.181+1G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Strong PM2

The NM_001378156.1(C1QB):​c.181+1G>C variant causes a splice donor, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: C1QB NM_001378156.1 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 5.03
• Publications: 0 publications found

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]

C1QB Gene-Disease associations (from GenCC):

• C1Q deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: ClinGen, Labcorp Genetics (formerly Invitae)

ENSG00000308848 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.26984128 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.9, offset of 26, new splice context is: ctgGTaata. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
C1QB	NM_001378156.1	c.181+1G>C		splice_donor_variant, intron_variant	Intron 2 of 2	ENST00000509305.6	NP_001365085.1
C1QB	NM_000491.5	c.187+1G>C		splice_donor_variant, intron_variant	Intron 2 of 2		NP_000482.3
C1QB	NM_001371184.3	c.181+1G>C		splice_donor_variant, intron_variant	Intron 3 of 3		NP_001358113.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
C1QB	ENST00000509305.6	c.181+1G>C		splice_donor_variant, intron_variant	Intron 2 of 2	1	NM_001378156.1	ENSP00000423689.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.19
CADD	Pathogenic	35
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		5.0
GERP RS		4.7
Mutation Taster		=3/97	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.62		Position offset: 25
DS_DL_spliceai		0.99		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs1361922961; hg19: chr1-22986137;