1-56929441-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000066.4(C8B):c.1739G>T(p.Cys580Phe) variant causes a missense change. The variant allele was found at a frequency of 0.000109 in 1,612,438 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000085 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00011 (0 hom.)
• Consequence: C8B NM_000066.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.74

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.967

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
C8B	NM_000066.4	c.1739G>T	p.Cys580Phe	missense_variant	12/12	ENST00000371237.9
C8B	NM_001278543.2	c.1583G>T	p.Cys528Phe	missense_variant	13/13
C8B	NM_001278544.2	c.1553G>T	p.Cys518Phe	missense_variant	13/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
C8B	ENST00000371237.9	c.1739G>T	p.Cys580Phe	missense_variant	12/12	1	NM_000066.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000854 AC: 13 AN: 152182 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000482

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.0000942

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000757 AC: 19 AN: 251152 Hom.: 0 AF XY: 0.000103 AC XY: 14 AN XY: 135752

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.000139

Gnomad NFE exome AF: 0.000141

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000111 AC: 162 AN: 1460256 Hom.: 0 Cov.: 33 AF XY: 0.000107 AC XY: 78 AN XY: 726422

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.000187

Gnomad4 NFE exome AF: 0.000122

Gnomad4 OTH exome AF: 0.000232

GnomAD4 genome AF: 0.0000854 AC: 13 AN: 152182 Hom.: 0 Cov.: 33 AF XY: 0.0000538 AC XY: 4 AN XY: 74338

Gnomad4 AFR AF: 0.0000482

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.0000942

Gnomad4 NFE AF: 0.000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000138 Hom.: 0

Bravo AF: 0.0000793

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000465 AC: 4

ExAC AF: 0.000107 AC: 13

EpiCase AF: 0.0000546

EpiControl AF: 0.000119

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

Mar 19, 2022

This sequence change replaces cysteine, which is neutral and slightly polar, with phenylalanine, which is neutral and non-polar, at codon 580 of the C8B protein (p.Cys580Phe). This variant is present in population databases (rs139167053, gnomAD 0.02%). This variant has not been reported in the literature in individuals affected with C8B-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Uncertain	0.078	D
BayesDel_noAF	Uncertain	0.13
Cadd	Pathogenic	27
Dann	Uncertain	0.99
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Benign	0.042	D
MetaRNN	Pathogenic	0.97	D;D;D
MetaSVM	Uncertain	0.022	D
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.50	T
PROVEAN	Pathogenic	-9.8	D;D;D
REVEL	Uncertain	0.54
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	.;D;D
Vest4		0.94
MVP		0.78
MPC		0.32
ClinPred		1.0	D
GERP RS		3.8
gMVP		0.97

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: rs139167053; hg19: chr1-57395114;