rs932962404

chr2-227089866-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Moderate PM2 PP3_Strong

The NM_000092.5(COL4A4):c.1459+2C>T variant causes a splice donor change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,610,738 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 0.0000066 (0 hom., cov: 28)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: COL4A4 NM_000092.5 splice_donor
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.01

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.01754386 fraction of the gene. Cryptic splice site detected, with MaxEntScore 11, offset of 0 (no position change), new splice context is: aagGTaagt. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: BayesDel_addAF computational evidence supports a deleterious effect, 0.625

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL4A4	NM_000092.5	c.1459+2C>T		splice_donor_variant		ENST00000396625.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL4A4	ENST00000396625.5	c.1459+2C>T		splice_donor_variant		5	NM_000092.5	P1

Frequencies

GnomAD3 genomes AF: 0.00000659 AC: 1 AN: 151822 Hom.: 0 Cov.: 28

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000401 AC: 1 AN: 249384 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135308

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: 0.00000883

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1458916 Hom.: 0 Cov.: 28 AF XY: 0.00000275 AC XY: 2 AN XY: 726018

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000659 AC: 1 AN: 151822 Hom.: 0 Cov.: 28 AF XY: 0.00 AC XY: 0 AN XY: 74102

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: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Dec 21, 2017

The c.1459+2C>T variant in COL4A4 has not been previously reported in individual s with hearing loss or Alport syndrome, but has been identified in 1/111608 Euro pean chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broad institute.org/; dbSNP rs932962404). Although this variant has been seen in the g eneral population, its frequency is not high enough to rule out a pathogenic rol e. This variant occurs in the invariant region (+/- 1/2) of the splice consensus sequence but computational tools do not suggest an impact to splicing. However, this information is not predictive enough to rule out pathogenicity. In summary , the clinical significance of the c.1459+2C>T variant is uncertain. ACMG/AMP Cr iteria applied: PM2. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	0.040
Cadd	Benign	20
Dann	Benign	0.95
Eigen	Pathogenic	0.79
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Benign	0.72	D
MutationTaster	Benign	1.0	D;D
GERP RS		3.9

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: rs932962404; hg19: chr2-227954582;