9-121074757-CA-C

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_Strong PM2 PP5

The NM_001317163.2(C5):c.79del(p.Cys27AlafsTer20) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000332 in 301,028 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000033 (0 hom.)
• Consequence: C5 NM_001317163.2 frameshift
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: -1.48

Genes affected

C5 (HGNC:1331): (complement C5) This gene encodes a component of the complement system, a part of the innate immune system that plays an important role in inflammation, host homeostasis, and host defense against pathogens. The encoded preproprotein is proteolytically processed to generate multiple protein products, including the C5 alpha chain, C5 beta chain, C5a anaphylatoxin and C5b. The C5 protein is comprised of the C5 alpha and beta chains, which are linked by a disulfide bridge. Cleavage of the alpha chain by a convertase enzyme results in the formation of the C5a anaphylatoxin, which possesses potent spasmogenic and chemotactic activity, and the C5b macromolecular cleavage product, a subunit of the membrane attack complex (MAC). Mutations in this gene cause complement component 5 deficiency, a disease characterized by recurrent bacterial infections. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2015]

CNTRL (HGNC:1858): (centriolin) This gene encodes a centrosomal protein required for the centrosome to function as a microtubule organizing center. The gene product is also associated with centrosome maturation. One version of stem cell myeloproliferative disorder is the result of a reciprocal translocation between chromosomes 8 and 9, with the breakpoint associated with fibroblast growth factor receptor 1 and centrosomal protein 1. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 12 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-121074757-CA-C is Pathogenic according to our data. Variant chr9-121074757-CA-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1049860.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
C5	NM_001317163.2	c.79del	p.Cys27AlafsTer20	frameshift_variant	1/41

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
C5	ENST00000696281.1	c.79del	p.Cys27AlafsTer20	frameshift_variant	1/42
C5	ENST00000696284.1	n.416del		non_coding_transcript_exon_variant	1/5
C5	ENST00000696285.1	n.135del		non_coding_transcript_exon_variant	1/3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000785 AC: 1 AN: 127400 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 69742

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: 0.0000212

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000332 AC: 1 AN: 301028 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 171520

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: 0.00000631

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

-

The C5 p.C27fs variant was not identified in the literature nor was it identified in ClinVar. The variant was identified in dbSNP (ID: rs1362872776) and in control databases in 1 of 127400 chromosomes at a frequency of 0.000007849 (Genome Aggregation Database March 6, 2019, v2.1.1). The variant was observed in the European (non-Finnish) population in 1 of 47176 chromosomes (freq: 0.000021), but was not observed in the African, Latino, Ashkenazi Jewish, East Asian, European (Finnish), Other, or South Asian populations. The c.79delT variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at codon 27 and leads to a premature stop codon. This alteration is then predicted to result in a truncated or absent protein and loss of function. Loss of function variants of the C5 gene are an established mechanism of disease in C5 deficiency and is the type of variant expected to cause the disorder when found in the homozygous or compound heterozygous state. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time although we would lean towards a more pathogenic role for this variant. This variant is classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs1362872776; hg19: chr9-123837035;