rs757347274

Positions:

• chr1-235470849-C-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1_Moderate PM2 PP3_Strong PP5_Very_Strong

The NM_152490.5(B3GALNT2):​c.762+1G>A variant causes a splice donor change. The variant allele was found at a frequency of 0.0000248 in 1,612,694 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. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000026 (0 hom.)
• Consequence: B3GALNT2 NM_152490.5 splice_donor
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 5.72

Genes affected

B3GALNT2 (HGNC:28596): (beta-1,3-N-acetylgalactosaminyltransferase 2) This gene encodes a member of the glycosyltransferase 31 family. The encoded protein synthesizes GalNAc:beta-1,3GlcNAc, a novel carbohydrate structure, on N- and O-glycans. Alternatively spliced transcript variants that encode different isoforms have been described. [provided by RefSeq, Mar 2013]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PVS1: Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.03659348 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 1-235470849-C-T is Pathogenic according to our data. Variant chr1-235470849-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 522103.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
B3GALNT2	NM_152490.5	c.762+1G>A		splice_donor_variant		ENST00000366600.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
B3GALNT2	ENST00000366600.8	c.762+1G>A		splice_donor_variant		1	NM_152490.5	P1

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 152012 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000478 AC: 12 AN: 250952 Hom.: 0 AF XY: 0.0000295 AC XY: 4 AN XY: 135592

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.000894

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000260 AC: 38 AN: 1460682 Hom.: 0 Cov.: 31 AF XY: 0.0000220 AC XY: 16 AN XY: 726542

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.000843

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000720

Gnomad4 OTH exome AF: 0.0000994

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 152012 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74242

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000304 Hom.: 0

ExAC AF: 0.0000412 AC: 5

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type a, 11 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 22, 2022	In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 522103). Disruption of this splice site has been observed in individual(s) with clinical features of B3GALNT2-related conditions (PMID: 31130284). This variant is present in population databases (rs757347274, gnomAD 0.09%). This sequence change affects a donor splice site in intron 6 of the B3GALNT2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in B3GALNT2 are known to be pathogenic (PMID: 23453667). -
Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Oct 31, 2018	- -

Inborn genetic diseases Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 29, 2017

- -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Dec 13, 2018

Canonical splice site variant predicted to result in an in-frame deletion of a critical region; Not observed at a significant frequency in large population cohorts (Lek et al., 2016; McVean et al., 2012; Exome Variant Server) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.30
CADD	Pathogenic	28
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Uncertain	0.93	D
MutationTaster	Benign	1.0	D;D
GERP RS		5.3

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs757347274; hg19: chr1-235634163;