1-56949599-G-T

Variant names:

• chr1-56949599-G-T
• rs140813121
• NM_000066.4:c.820C>A

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_000066.4(C8B):​c.820C>A​(p.Arg274Arg) variant causes a synonymous 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: C8B NM_000066.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.57
• Publications: 7 publications found

Genes affected

C8B (HGNC:1353): (complement C8 beta chain) This gene encodes one of the three subunits of the complement component 8 (C8) protein. C8 is composed of equimolar amounts of alpha, beta and gamma subunits, which are encoded by three separate genes. C8 is one component of the membrane attack complex, which mediates cell lysis, and it initiates membrane penetration of the complex. This protein mediates the interaction of C8 with the C5b-7 membrane attack complex precursor. In humans deficiency of this protein is associated with increased risk of meningococcal infections. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jun 2013]

C8B Gene-Disease associations (from GenCC):

• type II complement component 8 deficiency

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.82).
• BP7: Synonymous conserved (PhyloP=1.57 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000066.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	C8B	NM_000066.4	MANE Select	c.820C>A	p.Arg274Arg	synonymous	Exon 6 of 12	NP_000057.3	P07358
	C8B	NM_001278543.2		c.664C>A	p.Arg222Arg	synonymous	Exon 7 of 13	NP_001265472.2
	C8B	NM_001278544.2		c.634C>A	p.Arg212Arg	synonymous	Exon 7 of 13	NP_001265473.2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	C8B	ENST00000371237.9	TSL:1 MANE Select	c.820C>A	p.Arg274Arg	synonymous	Exon 6 of 12	ENSP00000360281.4	P07358
	C8B	ENST00000696164.1		c.820C>A	p.Arg274Arg	synonymous	Exon 7 of 13	ENSP00000512454.1	A0A8Q3WL56
	C8B	ENST00000875298.1		c.820C>A	p.Arg274Arg	synonymous	Exon 7 of 13	ENSP00000545357.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.82
CADD	Benign	1.1
DANN	Benign	0.48
PhyloP100		1.6
Mutation Taster		=100/0	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs140813121; hg19: chr1-57415272;