1-56929539-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000066.4(C8B):c.1641G>C(p.Lys547Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000197 in 152,228 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: 𝑓 0.000020 (0 hom., cov: 33)
• Consequence: C8B NM_000066.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.149

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.0848082).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
C8B	NM_000066.4	c.1641G>C	p.Lys547Asn	missense_variant	12/12	ENST00000371237.9
C8B	NM_001278543.2	c.1485G>C	p.Lys495Asn	missense_variant	13/13
C8B	NM_001278544.2	c.1455G>C	p.Lys485Asn	missense_variant	13/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
C8B	ENST00000371237.9	c.1641G>C	p.Lys547Asn	missense_variant	12/12	1	NM_000066.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152228 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 33

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152228 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74356

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.000131

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 07, 2022

This sequence change replaces lysine, which is basic and polar, with asparagine, which is neutral and polar, at codon 547 of the C8B protein (p.Lys547Asn). 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. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The asparagine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. This variant has not been reported in the literature in individuals affected with C8B-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.01%). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Benign	-0.35	T
BayesDel_noAF	Benign	-0.74
Cadd	Benign	4.2
Dann	Benign	0.94
Eigen	Benign	-1.1
Eigen_PC	Benign	-0.99
FATHMM_MKL	Benign	0.24	N
M_CAP	Benign	0.0040	T
MetaRNN	Benign	0.085	T;T;T
MetaSVM	Benign	-0.95	T
MutationTaster	Benign	0.81	D;D;N
PrimateAI	Benign	0.27	T
PROVEAN	Benign	0.62	N;N;N
REVEL	Benign	0.050
Sift	Benign	0.50	T;T;T
Sift4G	Benign	0.68	T;T;T
Polyphen		0.0010, 0.0	.;B;B
Vest4		0.062
MutPred		0.48		Loss of methylation at K547 (P = 0.0023);.;.;
MVP		0.20
MPC		0.041
ClinPred		0.15	T
GERP RS		-3.4
gMVP		0.50

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: rs777478006; hg19: chr1-57395212;