Genetic Variant B3GLCT:c.660+1G>T (chr13-31269278-G-T) – ACMG Classification: Pathogenic (10 pts)

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1PM2

The NM_194318.4(B3GLCT):c.660+1G>T variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000139 in 1,436,524 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

B3GLCT
NM_194318.4 splice_donor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 8.71

Publications

0 publications found

Variant links:

Genes affected

B3GLCT (HGNC:20207): (beta 3-glucosyltransferase) The protein encoded by this gene is a beta-1,3-glucosyltransferase that transfers glucose to O-linked fucosylglycans on thrombospondin type-1 repeats (TSRs) of several proteins. The encoded protein is a type II membrane protein. Defects in this gene are a cause of Peters-plus syndrome (PPS).[provided by RefSeq, Mar 2009]

B3GLCT Gene-Disease associations (from GenCC):

Peters plus syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet, G2P, PanelApp Australia

B3GLCT links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.

PM2

Very rare variant in population databases, with high coverage;

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_194318.4. 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
	B3GLCT	NM_194318.4	MANE Select	c.660+1G>T		splice_donor intron	N/A	NP_919299.3

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	B3GLCT	ENST00000343307.5	TSL:1 MANE Select	c.660+1G>T		splice_donor intron	N/A	ENSP00000343002.4
	B3GLCT	ENST00000461652.2	TSL:3	n.275+1G>T		splice_donor intron	N/A

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000139

AC:

AN:

1436524

Hom.:

Cov.:

AF XY:

0.00000279

AC XY:

AN XY:

716314

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:

32974

American (AMR)

AF:

0.00

AC:

AN:

44636

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25940

East Asian (EAS)

AF:

0.00

AC:

AN:

39494

South Asian (SAS)

AF:

0.00

AC:

AN:

85606

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52972

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5706

European-Non Finnish (NFE)

AF:

0.00000184

AC:

AN:

1089590

Other (OTH)

AF:

0.00

AC:

AN:

59606

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.00233887), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.350

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

BayesDel_addAF

Pathogenic

0.45

BayesDel_noAF

Pathogenic

0.41

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

1.3

Eigen_PC

Pathogenic

1.2

FATHMM_MKL

Pathogenic

0.99

PhyloP100

8.7

GERP RS

6.1

Mutation Taster

=0/100

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

0.99

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.99

Position offset: -1

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