Genetic Variant NM_004455.3:c.92G>T (chr1-26022738-G-T) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_004455.3(EXTL1):c.92G>T(p.Arg31Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,780 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R31H) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

EXTL1
NM_004455.3 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 1.70

Publications

3 publications found

Variant links:

Genes affected

EXTL1 (HGNC:3515): (exostosin like glycosyltransferase 1) This gene is a member of the multiple exostoses (EXT) family of glycosyltransferases, which function in the chain polymerization of heparan sulfate and heparin. The encoded protein harbors alpha 1,4- N-acetylglucosaminyltransferase activity, and is involved in chain elongation of heparan sulfate and possibly heparin. [provided by RefSeq, Jul 2008]

EXTL1 links:

ENSG00000310101 (HGNC:):

ENSG00000310101 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_004455.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	EXTL1	NM_004455.3	MANE Select	c.92G>T	p.Arg31Leu	missense	Exon 1 of 11	NP_004446.2	Q92935

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
EXTL1	ENST00000374280.4	TSL:1 MANE Select	c.92G>T	p.Arg31Leu	missense	Exon 1 of 11	ENSP00000363398.3	Q92935
EXTL1	ENST00000882621.1		c.92G>T	p.Arg31Leu	missense	Exon 1 of 11	ENSP00000552680.1
EXTL1	ENST00000882616.1		c.92G>T	p.Arg31Leu	missense	Exon 1 of 10	ENSP00000552675.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00

AC:

AN:

251162

AF XY:

0.00

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:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461780

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:

33478

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53374

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111968

Other (OTH)

AF:

0.0000166

AC:

AN:

60392

⚠️ 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: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.11

BayesDel_addAF

Pathogenic

0.16

BayesDel_noAF

Uncertain

0.0

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.0086

Eigen

Uncertain

0.43

Eigen_PC

Uncertain

0.40

FATHMM_MKL

Uncertain

0.87

LIST_S2

Benign

0.72

M_CAP

Benign

0.046

MetaRNN

Uncertain

0.52

MetaSVM

Uncertain

0.62

MutationAssessor

Uncertain

2.1

PhyloP100

1.7

PrimateAI

Benign

0.46

PROVEAN

Benign

-1.9

REVEL

Uncertain

0.49

Sift

Benign

0.23

Sift4G

Benign

0.22

Polyphen

0.99

Vest4

0.49

MutPred

0.45

Loss of methylation at R31 (P = 0.0244)

MVP

0.77

MPC

0.28

ClinPred

0.70

GERP RS

4.3

Varity_R

0.16

gMVP

0.79

Mutation Taster

=74/26

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

Details are displayed if max score is > 0.2

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

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

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over