chr2-227059468-C-T

Variant names:

• chr2-227059468-C-T
• rs569681869
• NM_000092.5:c.2320G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_000092.5(COL4A4):​c.2320G>A​(p.Gly774Ser) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,888 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 Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G774R) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: COL4A4 NM_000092.5 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.10
• Publications: 0 publications found

Genes affected

COL4A4 (HGNC:2206): (collagen type IV alpha 4 chain) This gene encodes one of the six subunits of type IV collagen, the major structural component of basement membranes. This particular collagen IV subunit, however, is only found in a subset of basement membranes. Like the other members of the type IV collagen gene family, this gene is organized in a head-to-head conformation with another type IV collagen gene so that each gene pair shares a common promoter. Mutations in this gene are associated with type II autosomal recessive Alport syndrome (hereditary glomerulonephropathy) and with familial benign hematuria (thin basement membrane disease). Two transcripts, differing only in their transcription start sites, have been identified for this gene and, as is common for collagen genes, multiple polyadenylation sites are found in the 3' UTR. [provided by RefSeq, Jul 2008]

COL4A4 Gene-Disease associations (from GenCC):

• autosomal recessive Alport syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, G2P, Orphanet, Ambry Genetics, Myriad Women’s Health
• Alport syndrome

  Inheritance: SD Classification: DEFINITIVE Submitted by: ClinGen
• hematuria, benign familial, 1

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Ambry Genetics
• autosomal dominant Alport syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 5 uncertain in NM_000092.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-227059468-C-G is described in CliVar as Conflicting_classifications_of_pathogenicity. Clinvar id is 242442.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 2-227059468-C-T is Pathogenic according to our data. Variant chr2-227059468-C-T is described in CliVar as Likely_pathogenic. Clinvar id is 2954930.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr2-227059468-C-T is described in CliVar as Likely_pathogenic. Clinvar id is 2954930.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL4A4	NM_000092.5	c.2320G>A	p.Gly774Ser	missense_variant	Exon 28 of 48	ENST00000396625.5	NP_000083.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL4A4	ENST00000396625.5	c.2320G>A	p.Gly774Ser	missense_variant	Exon 28 of 48	5	NM_000092.5	ENSP00000379866.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461888 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727246

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112006

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Dec 15, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 774 of the COL4A4 protein (p.Gly774Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with COL4A4-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt COL4A4 protein function with a positive predictive value of 95%. This variant disrupts the p.Gly774 amino acid residue in COL4A4. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 17396119, 26934356, 28632965, 33532864, 34584596). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.48
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.55	D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.90	D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	4.0	H
PhyloP100		5.1
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-5.8	D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.97
MutPred		0.93		Gain of phosphorylation at G774 (P = 0.0108);
MVP		0.94
MPC		0.58
ClinPred		0.99	D
GERP RS		6.0
Varity_R		0.60
gMVP		0.89
Mutation Taster		=10/90	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs569681869; hg19: chr2-227924184;