Genetic Variant EXT2:p.Leu549Leu (chr11-44206944-G-A) – ACMG Classification: Likely_benign (-3 pts)

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2BP4_StrongBP7

The NM_207122.2(EXT2):c.1647G>A(p.Leu549Leu) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,764 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. L549L) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

EXT2
NM_207122.2 synonymous

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 1.12

Publications

0 publications found

Variant links:

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: ClinGen, Ambry Genetics, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, G2P
seizures-scoliosis-macrocephaly syndrome
Inheritance: AR Classification: STRONG, SUPPORTIVE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
hereditary multiple osteochondromas
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

EXT2 links:

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new If you want to explore the variant's impact on the transcript NM_207122.2, check out the Mutation Effect Viewer. This is especially useful for frameshift variants or if you want to visualize the effect of exon loss / intron retention.

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.49).

BP7

Synonymous conserved (PhyloP=1.12 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_207122.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
EXT2	NM_207122.2	MANE Select	c.1647G>A	p.Leu549Leu	synonymous	Exon 10 of 14	NP_997005.1	Q93063-1
EXT2	NM_000401.3		c.1746G>A	p.Leu582Leu	synonymous	Exon 10 of 14	NP_000392.3	Q93063-3
EXT2	NM_001178083.3		c.1677G>A	p.Leu559Leu	synonymous	Exon 11 of 15	NP_001171554.1	Q93063-2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
EXT2	ENST00000533608.7	TSL:1 MANE Select	c.1647G>A	p.Leu549Leu	synonymous	Exon 10 of 14	ENSP00000431173.2	Q93063-1
EXT2	ENST00000358681.8	TSL:1	c.1677G>A	p.Leu559Leu	synonymous	Exon 11 of 15	ENSP00000351509.4	Q93063-2
EXT2	ENST00000343631.4	TSL:1	c.1647G>A	p.Leu549Leu	synonymous	Exon 11 of 15	ENSP00000342656.3	Q93063-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461764

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727196

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

33476

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39684

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53386

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111950

Other (OTH)

AF:

0.00

AC:

AN:

60388

⚠️ 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.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.49

CADD

Benign

7.0

(source)

DANN

Benign

0.44

PhyloP100

1.1

Mutation Taster

=99/1

polymorphism

(source)

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over