chr1-21876613-C-A

Variant names:

• chr1-21876613-C-A
• rs137904249
• NM_005529.7:c.2725G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_005529.7(HSPG2):​c.2725G>T​(p.Gly909Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000116 in 1,461,884 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G909S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: HSPG2 NM_005529.7 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.58
• Publications: 12 publications found

Genes affected

HSPG2 (HGNC:5273): (heparan sulfate proteoglycan 2) This gene encodes the perlecan protein, which consists of a core protein to which three long chains of glycosaminoglycans (heparan sulfate or chondroitin sulfate) are attached. The perlecan protein is a large multidomain proteoglycan that binds to and cross-links many extracellular matrix components and cell-surface molecules. It has been shown that this protein interacts with laminin, prolargin, collagen type IV, FGFBP1, FBLN2, FGF7 and transthyretin, etc., and it plays essential roles in multiple biological activities. Perlecan is a key component of the vascular extracellular matrix, where it helps to maintain the endothelial barrier function. It is a potent inhibitor of smooth muscle cell proliferation and is thus thought to help maintain vascular homeostasis. It can also promote growth factor (e.g., FGF2) activity and thus stimulate endothelial growth and re-generation. It is a major component of basement membranes, where it is involved in the stabilization of other molecules as well as being involved with glomerular permeability to macromolecules and cell adhesion. Mutations in this gene cause Schwartz-Jampel syndrome type 1, Silverman-Handmaker type of dyssegmental dysplasia, and tardive dyskinesia. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, May 2014]

HSPG2 Gene-Disease associations (from GenCC):

• Schwartz-Jampel syndrome type 1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), G2P
• Silverman-Handmaker type dyssegmental dysplasia

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, ClinGen, Labcorp Genetics (formerly Invitae)
• Schwartz-Jampel syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005529.7. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HSPG2	NM_005529.7	MANE Select	c.2725G>T	p.Gly909Cys	missense	Exon 22 of 97	NP_005520.4
	HSPG2	NM_001291860.2		c.2728G>T	p.Gly910Cys	missense	Exon 22 of 97	NP_001278789.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HSPG2	ENST00000374695.8	TSL:1 MANE Select	c.2725G>T	p.Gly909Cys	missense	Exon 22 of 97	ENSP00000363827.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251378 AF XY: 0.00000736

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000116 AC: 17 AN: 1461884 Hom.: 0 Cov.: 33 AF XY: 0.00000825 AC XY: 6 AN XY: 727246

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

American (AMR) AF: 0.00 AC: 0 AN: 44720

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

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

South Asian (SAS) AF: 0.00 AC: 0 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: 0.0000153 AC: 17 AN: 1112006

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

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 2

Bravo AF: 0.00000378

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Apr 17, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2725G>T (p.G909C) alteration is located in exon 21 (coding exon 21) of the HSPG2 gene. This alteration results from a G to T substitution at nucleotide position 2725, causing the glycine (G) at amino acid position 909 to be replaced by a cysteine (C). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.80
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.21
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.85	D
Eigen	Uncertain	0.49
Eigen_PC	Uncertain	0.29
FATHMM_MKL	Benign	0.75	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.085	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Uncertain	0.59	D
MutationAssessor	Pathogenic	4.3	H
PhyloP100		5.6
PrimateAI	Uncertain	0.54	T
PROVEAN	Pathogenic	-5.8	D
REVEL	Uncertain	0.55
Sift	Uncertain	0.0020	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.89
MutPred		0.93		Loss of disorder (P = 0.2108)
MVP		0.81
MPC		0.81
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.63
gMVP		0.89
Mutation Taster		=57/43	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.11		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: rs137904249; hg19: chr1-22203106;