chr16-56511159-C-T

Variant names:

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2PP3_StrongPP5

The NM_031885.5(BBS2):c.471G>A(p.Thr157Thr) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000496 in 1,613,706 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000041 ( 0 hom. )

Consequence

BBS2
NM_031885.5 splice_region, synonymous

Scores

Splicing: ADA: 1.000

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2U:2

Conservation

PhyloP100: 1.04

Variant links:

Genes affected

BBS2 (HGNC:967): (Bardet-Biedl syndrome 2) This gene is a member of the Bardet-Biedl syndrome (BBS) gene family. Bardet-Biedl syndrome is an autosomal recessive disorder characterized by severe pigmentary retinopathy, obesity, polydactyly, renal malformation and cognitive disability. The proteins encoded by BBS gene family members are structurally diverse and the similar phenotypes exhibited by mutations in BBS gene family members is likely due to their shared roles in cilia formation and function. Many BBS proteins localize to the basal bodies, ciliary axonemes, and pericentriolar regions of cells. BBS proteins may also be involved in intracellular trafficking via microtubule-related transport. The protein encoded by this gene forms a multiprotein BBSome complex with seven other BBS proteins.[provided by RefSeq, Oct 2014]

BBS2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

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 16-56511159-C-T is Pathogenic according to our data. Variant chr16-56511159-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 551904.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=2}. Variant chr16-56511159-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BBS2	NM_031885.5 link	c.471G>A	p.Thr157Thr	splice_region_variant, synonymous_variant	Exon 3 of 17	ENST00000245157.11	NP_114091.4	Q9BXC9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BBS2	ENST00000245157.11 link	c.471G>A	p.Thr157Thr	splice_region_variant, synonymous_variant	Exon 3 of 17	1	NM_031885.5	ENSP00000245157.5		Q9BXC9

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151980

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000398

AC:

AN:

251298

Hom.:

AF XY:

0.00000736

AC XY:

AN XY:

135816

show subpopulations

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 SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000410

AC:

AN:

1461726

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

727156

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000232

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000270

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000132

AC:

AN:

151980

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74218

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.0000655

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000756

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Bardet-Biedl syndrome 2

Pathogenic:1Uncertain:2

Neuberg Centre For Genomic Medicine, NCGM

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The synonymous variant p.T157= in BBS2 (NM_031885.5) has been previously reported in an individual with retinis pigmentosa (Wang F et al). The variant has been submitted to ClinVar as Uncertain significance.The p.T157= variant is observed in 1/30,612 (0.0033%) alleles from individuals of South Asian background in gnomAD Exomes and is novel (not in any individuals) in 1000 Genomes. The variant affects an invariant splice nucleotide and hence may affect splicing. The p.T157= variant is predicted to disrupt splicing by 3 of 4 splice site algorithms. Since the variant is a synonymous change it is classified as Uncertain Significance. -

May 16, 2017

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 27, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Bardet-Biedl syndrome

Pathogenic:1

Mar 14, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ClinVar contains an entry for this variant (Variation ID: 551904). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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. This sequence change affects codon 157 of the BBS2 mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the BBS2 protein. This variant also falls at the last nucleotide of exon 3, which is part of the consensus splice site for this exon. This variant is present in population databases (rs749983428, gnomAD 0.003%). This variant has been observed in individuals with Bardet-Biedl syndrome and/or retinitis pigmentosa (PMID: 24154662, 29588463; Invitae). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.16

CADD

Benign

DANN

Benign

0.94

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.96

SpliceAI score (max)

0.88

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.88

Position offset: 0

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over