X-108666549-G-T

Variant names:

• chrX-108666549-G-T
• rs104886237
• NM_033380.3:c.3508G>T

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_033380.3(COL4A5):​c.3508G>T​(p.Gly1170Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000913 in 1,094,764 control chromosomes in the GnomAD database, with no homozygous occurrence. There are no hemizygote samples in GnomAD. 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. G1170S) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 23)
  • Exomes 𝑓: 9.1e-7 (0 hom. 0 hem.)
• Consequence: COL4A5 NM_033380.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.39
• Publications: 0 publications found

Genes affected

COL4A5 (HGNC:2207): (collagen type IV alpha 5 chain) This gene encodes one of the six subunits of type IV collagen, the major structural component of basement membranes. Mutations in this gene are associated with X-linked Alport syndrome, also known as hereditary nephritis. 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. Alternatively spliced transcript variants have been identified for this gene. [provided by RefSeq, Aug 2010]

COL4A5 Gene-Disease associations (from GenCC):

• Alport syndrome

  Inheritance: XL Classification: DEFINITIVE Submitted by: ClinGen, G2P
• X-linked Alport syndrome

  Inheritance: XL Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: PanelApp Australia, Genomics England PanelApp, Myriad Women’s Health, Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Pathogenic. The variant received 13 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 8 uncertain in NM_033380.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrX-108666549-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 24638.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 538 curated pathogenic missense variants (we use a threshold of 10). The gene has 138 curated benign missense variants. Gene score misZ: 2.4995 (below the threshold of 3.09). Trascript score misZ: NaN (below the threshold of 3.09). GenCC associations: The gene is linked to X-linked Alport syndrome, Alport syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant X-108666549-G-T is Pathogenic according to our data. Variant chrX-108666549-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 1502533.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL4A5	NM_033380.3	c.3508G>T	p.Gly1170Cys	missense_variant	Exon 39 of 53	ENST00000328300.11	NP_203699.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL4A5	ENST00000328300.11	c.3508G>T	p.Gly1170Cys	missense_variant	Exon 39 of 53	1	NM_033380.3	ENSP00000331902.7
COL4A5	ENST00000361603.7	c.3508G>T	p.Gly1170Cys	missense_variant	Exon 39 of 51	2		ENSP00000354505.2

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome AF: 9.13e-7 AC: 1 AN: 1094764 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 360546

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 26291

American (AMR) AF: 0.00 AC: 0 AN: 35004

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 19337

East Asian (EAS) AF: 0.00 AC: 0 AN: 30049

South Asian (SAS) AF: 0.00 AC: 0 AN: 53378

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 40315

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4132

European-Non Finnish (NFE) AF: 0.00000119 AC: 1 AN: 840312

Other (OTH) AF: 0.00 AC: 0 AN: 45946

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 23

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Aug 30, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant disrupts the triple helix domain of COL4A5. Glycine residues within the Gly-Xaa-Yaa repeats of the triple helix domain are required for the structure and stability of fibrillar collagens (PMID: 7695699, 8218237, 19344236). In COL4A5, missense variants at these glycine residues are significantly enriched in individuals with disease (PMID: 23720012, 27627812) compared to the general population (ExAC). This sequence change replaces glycine with cysteine at codon 1170 of the COL4A5 protein (p.Gly1170Cys). The glycine residue is highly conserved and there is a large physicochemical difference between glycine and cysteine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with COL4A5-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 COL4A5 protein function. This variant disrupts the p.Gly1170 amino acid residue in COL4A5. Other variant(s) that disrupt this residue have been observed in individuals with COL4A5-related conditions (PMID: 28542346, 30577881), which suggests that this may be a clinically significant amino acid residue. 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.

X-linked Alport syndrome Pathogenic:1

Oct 15, 2024

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is classified as Pathogenic. Evidence in support of pathogenic classification: Variant is present in gnomAD <0.001 for a dominant condition (v4: 1 heterozygote(s), 0 homozygote(s), 0 hemizygote(s)); This variant has limited previous evidence of pathogenicity in an unrelated individual(s). This variant has been classified as likely pathogenic by one clinical laboratory in ClinVar; Other missense variant(s) comparable to the one identified in this case have very strong previous evidence for pathogenicity. p.(Gly1170Arg), p.(Gly1170Ser), p.(Gly1170Asp) and p.(Gly1170Val) have been classified as likely pathogenic or pathogenic by multiple clinical laboratories in ClinVar; Variant is located in the well-established triple helical Gly-X-Y repeat region and affects a glycine residue (DECIPHER, PMID: 33854215); Missense variant predicted to be damaging by an in silico tool or highly conserved with a major amino acid change. Additional information: Variant is predicted to result in a missense amino acid change from glycine to cysteine; This variant is heterozygous; This gene is associated with X-linked dominant disease. Males are typically more severely affected than females (PMID: 19965530); An alternative amino acid change at the same position has been observed in gnomAD (v4: 3 heterozygote(s), 0 homozygote(s), 1 hemizygote(s)); No published segregation evidence has been identified for this variant; No published functional evidence has been identified for this variant; Dominant negative and loss of function are known mechanisms of disease in this gene and are associated with X-linked Alport syndrome 1 (MIM#301050). Dominant negative is caused mostly by glycine substitutions that affect the conformation of the protein, and loss of function can be caused by either protein truncating or missense variants (PMID: 24046192, 12028435); Variants in this gene are known to have variable expressivity. There is intrafamilial variability among affected carrier females, possibly due to variable X-inactivation (PMID: 14514738); Inheritance information for this variant is not currently available in this individual.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.74	D
BayesDel_noAF	Pathogenic	0.82
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Benign	0.0	.;D
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	4.6	H;H
PhyloP100		8.4
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-8.0	D;D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Vest4		0.98
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.99
gMVP		1.0
Mutation Taster		=10/90	disease causing

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

Other links and lift over

dbSNP: rs104886237; hg19: chrX-107909779;