Genetic Variant C8A:p.Ala36Val (chr1-56867638-C-T) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

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

The NM_000562.3(C8A):c.107C>T(p.Ala36Val) variant causes a missense change. The variant allele was found at a frequency of 0.0000434 in 1,613,696 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A36E) has been classified as Benign.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000046 ( 0 hom. )

Consequence

C8A
NM_000562.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 4.35

Variant links:

Genes affected

C8A (HGNC:1352): (complement C8 alpha chain) C8 is a component of the complement system and contains three polypeptides, alpha, beta and gamma. This gene encodes the alpha subunit of C8. C8 participates in the formation of the membrane attack complex (MAC). The MAC assembles on bacterial membranes to form a pore, permitting disruption of bacterial membrane organization. Mutations in this gene cause complement C8 alpha-gamma deficiency. [provided by RefSeq, Nov 2008]

C8A links:

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ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
C8A	NM_000562.3 link	c.107C>T	p.Ala36Val	missense_variant	Exon 2 of 11	ENST00000361249.4	NP_000553.1	P07357
C8A	XM_017002234.2 link	c.107C>T	p.Ala36Val	missense_variant	Exon 2 of 8		XP_016857723.1
C8A	XM_011542079.3 link	c.107C>T	p.Ala36Val	missense_variant	Exon 2 of 8		XP_011540381.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
C8A	ENST00000361249.4 link	c.107C>T	p.Ala36Val	missense_variant	Exon 2 of 11	1	NM_000562.3	ENSP00000354458.3		P07357

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152182

Hom.:

Cov.:

show subpopulations

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:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000199

AC:

AN:

251026

Hom.:

AF XY:

0.0000295

AC XY:

AN XY:

135648

show subpopulations

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:

0.00

Gnomad NFE exome

AF:

0.0000441

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000458

AC:

AN:

1461514

Hom.:

Cov.:

AF XY:

0.0000358

AC XY:

AN XY:

727070

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000531

Gnomad4 OTH exome

AF:

0.000132

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152182

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74332

show subpopulations

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:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.00000518

Hom.:

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not provided

Uncertain:1

Jul 30, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 36 of the C8A protein (p.Ala36Val). This variant is present in population databases (rs116201358, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with C8A-related conditions. ClinVar contains an entry for this variant (Variation ID: 1036284). 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: "Benign"; 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

Benign

0.12

BayesDel_addAF

Benign

-0.12

BayesDel_noAF

Benign

-0.28

CADD

Benign

DANN

Uncertain

1.0

DEOGEN2

Benign

0.061

Eigen

Benign

0.12

Eigen_PC

Benign

0.015

FATHMM_MKL

Benign

0.18

LIST_S2

Benign

0.81

M_CAP

Benign

0.029

MetaRNN

Uncertain

0.57

MetaSVM

Benign

-0.39

MutationAssessor

Uncertain

2.7

PrimateAI

Benign

0.33

PROVEAN

Benign

-1.4

REVEL

Uncertain

0.35

Sift

Uncertain

0.012

Sift4G

Uncertain

0.010

Polyphen

0.98

Vest4

0.43

MutPred

0.63

Gain of catalytic residue at A36 (P = 0.0537);

MVP

0.86

MPC

0.046

ClinPred

0.82

GERP RS

5.1

Varity_R

0.15

gMVP

0.32

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over