rs121908176

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_031885.5(BBS2):c.175C>T(p.Gln59Ter) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000229 in 1,614,002 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

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

Exomes 𝑓: 0.000024 ( 0 hom. )

Consequence

BBS2
NM_031885.5 stop_gained

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9

Conservation

PhyloP100: 9.69

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 Pathogenic. Variant got 18 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 16-56514623-G-A is Pathogenic according to our data. Variant chr16-56514623-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 4571.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-56514623-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS2	NM_031885.5 linkuse as main transcript	c.175C>T	p.Gln59Ter	stop_gained	2/17	ENST00000245157.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS2	ENST00000245157.11 linkuse as main transcript	c.175C>T	p.Gln59Ter	stop_gained	2/17	1	NM_031885.5	P1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152158

Hom.:

Cov.:

show subpopulations

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:

0.0000199

AC:

AN:

251274

Hom.:

AF XY:

0.0000294

AC XY:

AN XY:

135888

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:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000352

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.0000239

AC:

AN:

1461844

Hom.:

Cov.:

AF XY:

0.0000248

AC XY:

AN XY:

727218

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000288

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152158

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74328

show subpopulations

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:

0.0000306

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Bardet-Biedl syndrome 2

Pathogenic:5

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Aug 09, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Laboratory of Medical Genetics (UMR_S 1112), INSERM/Strasbourg University	Aug 09, 2022	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Sep 21, 2001	- -
Pathogenic, no assertion criteria provided	clinical testing	Counsyl	Aug 25, 2017	- -

Bardet-Biedl syndrome

Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 31, 2019	Variant summary: BBS2 c.175C>T (p.Gln59X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (eg. c.814C>T (p.Arg272X), c.823C>T (p.Arg275X), and c.1864C>T (p.Arg622X)). The variant allele was found at a frequency of 2.4e-05 in 246604 control chromosomes (gnomAD and publications). c.175C>T has been reported in the literature in individuals affected with features of Bardet-Biedl Syndrome (Katsanis_2001, Fitzgerald_2015). Katsanis_2001 proposed that this syndrome may not be a single-gene recessive disease but a complex trait requiring three mutant alleles to manifest the phenotype because an affected patient from one family carried triallelic variants BBS2 Q59X and Y24X in compound heterozygosity and BBS6 Q147X, while a sibling with the same biallelic variants in BBS2 without the BBS6 variant and father with BBS2 Q59X and BBS6 Q147X were healthy. Another publication, Abu-Safieh_2012, using a cohort of 29 BBS families was not able to support this triallelic model, arguing in favor of straightforward autosomal recessive BBS in most cases. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. A ClinVar submission from a clinical diagnostic laboratory (evaluation after 2014) cites the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Aug 11, 2023	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 4571). This premature translational stop signal has been observed in individual(s) with Bardet-Biedl syndrome (PMID: 11567139, 27659767). This variant is present in population databases (rs121908176, gnomAD 0.004%). This sequence change creates a premature translational stop signal (p.Gln59*) in the BBS2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in BBS2 are known to be pathogenic (PMID: 11285252, 20177705, 24608809, 26518167). -

not provided

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Apr 22, 2023

Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 27659767, 28911095, 26147798, 11567139, 21962508, 25533962, 21052717) -

Bardet-Biedl syndrome 2;C4225281:Retinitis pigmentosa 74

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

May 09, 2022

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.53

BayesDel_noAF

Pathogenic

0.66

Cadd

Pathogenic

Dann

Uncertain

1.0

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.93

FATHMM_MKL

Pathogenic

0.99

MutationTaster

Benign

1.0

A;A

Vest4

0.83

GERP RS

5.5

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.050

Details are displayed if max score is > 0.2

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