rs1469479748

Positions:

• chr2-227253310-AAG-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The ENST00000396578.8(COL4A3):​c.663_664del​(p.Arg221SerfsTer5) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000266 in 1,613,728 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000028 (0 hom.)
• Consequence: COL4A3 ENST00000396578.8 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 3.17

Genes affected

COL4A3 (HGNC:2204): (collagen type IV alpha 3 chain) Type IV collagen, the major structural component of basement membranes, is a multimeric protein composed of 3 alpha subunits. These subunits are encoded by 6 different genes, alpha 1 through alpha 6, each of which can form a triple helix structure with 2 other subunits to form type IV collagen. This gene encodes alpha 3. In the Goodpasture syndrome, autoantibodies bind to the collagen molecules in the basement membranes of alveoli and glomeruli. The epitopes that elicit these autoantibodies are localized largely to the non-collagenous C-terminal domain of the protein. A specific kinase phosphorylates amino acids in this same C-terminal region and the expression of this kinase is upregulated during pathogenesis. This gene is also linked to an autosomal recessive form of Alport syndrome. The mutations contributing to this syndrome are also located within the exons that encode this C-terminal region. 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. [provided by RefSeq, Jun 2010]

MFF-DT (HGNC:41067): (MFF divergent transcript)

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-227253310-AAG-A is Pathogenic according to our data. Variant chr2-227253310-AAG-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 553434.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-227253310-AAG-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL4A3	NM_000091.5	c.663_664del	p.Arg221SerfsTer5	frameshift_variant	12/52	ENST00000396578.8	NP_000082.2
MFF-DT	NR_102371.1	n.1592+5866_1592+5867del		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL4A3	ENST00000396578.8	c.663_664del	p.Arg221SerfsTer5	frameshift_variant	12/52	1	NM_000091.5	ENSP00000379823	P1
MFF-DT	ENST00000439598.6	n.1592+5866_1592+5867del		intron_variant, non_coding_transcript_variant		1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152220 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000161 AC: 4 AN: 249216 Hom.: 0 AF XY: 0.0000148 AC XY: 2 AN XY: 135182

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: 0.0000354

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000281 AC: 41 AN: 1461508 Hom.: 0 AF XY: 0.0000248 AC XY: 18 AN XY: 727102

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: 0.0000360

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152220 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74366

Gnomad4 AFR AF: 0.00

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: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Autosomal recessive Alport syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Feb 16, 2022	Variant summary: COL4A3 c.663_664delAG (p.Arg221SerfsX5) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant allele was found at a frequency of 1.6e-05 in 249216 control chromosomes. c.663_664delAG has been reported in the literature in at least one individual affected with Alport Syndrome, Autosomal Recessive (Storey_2013). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Aug 18, 2017	- -

not provided Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jan 24, 2024	Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Reported with a second variant (phase unknown) in a patient with renal biopsy suggestive of Alport syndrome in published literature (PMID: 24052634); This variant is associated with the following publications: (PMID: 24052634) -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 27, 2022	This sequence change creates a premature translational stop signal (p.Arg221Serfs*5) in the COL4A3 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in COL4A3 are known to be pathogenic (PMID: 8956999, 24854265, 26809805, 27281700). This variant is present in population databases (no rsID available, gnomAD 0.004%). This premature translational stop signal has been observed in individual(s) with autosomal recessive Alport syndrome (PMID: 24052634). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 553434). For these reasons, this variant has been classified as Pathogenic. -

Alport syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Oct 09, 2024

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Dominant negative and loss of function are known mechanisms of disease in this gene and are associated with Alport syndrome, MONDO:0018965, COL4A3-related. Glycine changes that are part of a G-X-Y repeat in the triple helix of a collagen domain are known to have a dominant negative effect (PMID: 12028435). (I) 0108 - This gene is associated with both recessive and dominant disease, Alport syndrome 3B (MIM#620536) and Alport syndrome 3A (MIM#104200), respectively (OMIM). (I) 0201 - Variant is predicted to cause nonsense-mediated decay (NMD) and loss of protein (premature termination codon is located at least 54 nucleotides upstream of the final exon-exon junction). (SP) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 (4 heterozygotes, 0 homozygotes). (SP) 0701 - Other NMD-predicted variants comparable to the one identified in this case have very strong previous evidence for pathogenicity. Many NMD-predicted variants have been reported as pathogenic (ClinVar). (SP) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported three times as pathogenic and once as likely pathogenic (ClinVar) and in an at least one compound heterozygous individual with autosomal recessive Alport syndrome (PMID:24052634). (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Autosomal dominant Alport syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Jan 18, 2019

This variant was determined to be pathogenic according to ACMG Guidelines, 2015 [PMID:25741868]. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs1469479748; hg19: chr2-228118026;