11-44124950-A-AGC

Variant names:

• chr11-44124950-A-AGC
• rs886041199
• NM_207122.2:c.906_907dupGC

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_207122.2(EXT2):​c.906_907dupGC​(p.His303ArgfsTer30) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,308 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: EXT2 NM_207122.2 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 1.32
• Publications: 1 publications found

Genes affected

EXT2 (HGNC:3513): (exostosin glycosyltransferase 2) This gene encodes one of two glycosyltransferases involved in the chain elongation step of heparan sulfate biosynthesis. Mutations in this gene cause the type II form of multiple exostoses. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene. [provided by RefSeq, Jul 2008]

EXT2 Gene-Disease associations (from GenCC):

• exostoses, multiple, type 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics, G2P
• seizures-scoliosis-macrocephaly syndrome

  Inheritance: AR Classification: STRONG, SUPPORTIVE, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), Orphanet
• hereditary multiple osteochondromas

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 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 11-44124950-A-AGC is Pathogenic according to our data. Variant chr11-44124950-A-AGC is described in ClinVar as [Pathogenic]. Clinvar id is 279805.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
EXT2	NM_207122.2	c.906_907dupGC	p.His303ArgfsTer30	frameshift_variant	Exon 5 of 14	ENST00000533608.7	NP_997005.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
EXT2	ENST00000533608.7	c.906_907dupGC	p.His303ArgfsTer30	frameshift_variant	Exon 5 of 14	1	NM_207122.2	ENSP00000431173.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461308 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726968

African (AFR) AF: 0.00 AC: 0 AN: 33462

American (AMR) AF: 0.0000447 AC: 2 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: 0.00 AC: 0 AN: 86230

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53406

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5304

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112004

Other (OTH) AF: 0.00 AC: 0 AN: 60342

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Exostoses, multiple, type 2;C4225248:Seizures-scoliosis-macrocephaly syndrome Pathogenic:1

Sep 18, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Exostoses, multiple, type 2 Pathogenic:1

Nov 18, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.His303Argfs*30) in the EXT2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in EXT2 are known to be pathogenic (PMID: 10679937, 19810120). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with hereditary multiple exostoses (PMID: 10750558, 11169766, 20425833). Invitae Evidence Modeling of clinical and family history, age, sex, and reported ancestry of multiple individuals with this EXT2 variant has been performed. This variant is expected to be pathogenic with a positive predictive value of at least 99%. This is a validated machine learning model that incorporates the clinical features of 50,122 individuals referred to our laboratory for EXT2 testing. This variant is also known as 907insGC. ClinVar contains an entry for this variant (Variation ID: 279805). For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:1

Nov 04, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in patients with hereditary multiple exostoses in published literature (PMID: 20425833, 10750558, 11169766); 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); This variant is associated with the following publications: (PMID: 11169766, 10750558, 20425833) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		1.3
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs886041199; hg19: chr11-44146500;