rs778090540

Variant summary

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

The NM_031885.5(BBS2):c.1438C>T(p.Arg480Ter) variant causes a stop gained change. The variant allele was found at a frequency of 0.0000242 in 1,614,004 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 (★★). Synonymous variant affecting the same amino acid position (i.e. R480R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000026 ( 0 hom. )

Consequence

BBS2
NM_031885.5 stop_gained

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7

Conservation

PhyloP100: 4.92

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 16-56499867-G-A is Pathogenic according to our data. Variant chr16-56499867-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 553353.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-56499867-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS2	NM_031885.5 linkuse as main transcript	c.1438C>T	p.Arg480Ter	stop_gained	12/17	ENST00000245157.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS2	ENST00000245157.11 linkuse as main transcript	c.1438C>T	p.Arg480Ter	stop_gained	12/17	1	NM_031885.5	P1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152164

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000239

AC:

AN:

251458

Hom.:

AF XY:

0.0000221

AC XY:

AN XY:

135902

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000544

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000462

Gnomad NFE exome

AF:

0.0000264

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000260

AC:

AN:

1461840

Hom.:

Cov.:

AF XY:

0.0000289

AC XY:

AN XY:

727226

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000252

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.0000187

Gnomad4 NFE exome

AF:

0.0000315

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152164

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74332

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000446

Hom.:

Bravo

AF:

0.0000113

ExAC

AF:

0.0000165

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.000119

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:7

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.	Nov 18, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Aug 24, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Rady Children's Institute for Genomic Medicine, Rady Children's Hospital San Diego	Oct 23, 2019	This nonsense variant found in exon 12 of 17 is predicted to result in loss of normal protein function. This variant has been previously reported as a compound heterozygous or homozygous change in patients with Bardet-Biedl Syndrome, including thoraco-abdominal abnormalities and congenital heart defects (PMID: 21052717, 24608809, 26325687, 30293640). It is present in the heterozygous state in the gnomAD population database at a frequency of 0.0024% (6/251,458) and thus is presumed to be rare. Based on the available evidence, the c.1438C>T (p.Arg480Ter) variant is classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Sep 13, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 09, 2019	The BBS2 c.1438C>T (p.Arg480Ter) variant is a stop gained variant which has been reported in at least five studies in which it is found in a total of four probands with Bardet-Biedl syndrome, including one in a homozygous state and three in a compound heterozygous state (Ansley et al. 2003; Janssen et al. 2011; Xing et al. 2014; Hirano et al. 2015; Olson et al. 2019). The homozygous individual and their unaffected father also carried two variants in cis in the BBS9 gene (Xing et al. 2014). In all families, the variant was identified in at least one unaffected parent in a heterozygous state. The variant was absent from 396 controls but is reported at a frequency of 0.00012 in the East Asian population of the Exome Aggregation Consortium. However, the frequency data are based on one allele, so the variant is presumed to be rare. Due to the potential impact of stop-gained variants and the supporting evidence, the p.Arg480Ter variant is classified as likely pathogenic for Bardet-Biedl syndrome. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Bardet-Biedl syndrome

Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Sep 19, 2019	Variant summary: BBS2 c.1438C>T (p.Arg480X) 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. The variant allele was found at a frequency of 2.4e-05 in 251458 control chromosomes (gnomAD). c.1438C>T has been reported in the literature in individuals affected with Bardet-Biedl Syndrome (Hirano_2015, Janssen_2011, Xing_2014). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three ClinVar submissions (evaluation after 2014) cite the variant twice as pathogenic and once as likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 13, 2023	This sequence change creates a premature translational stop signal (p.Arg480*) 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). This variant is present in population databases (rs778090540, gnomAD 0.006%). This premature translational stop signal has been observed in individuals with Bardet-Biedl syndrome (PMID: 21052717, 24608809). ClinVar contains an entry for this variant (Variation ID: 553353). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.51

BayesDel_noAF

Pathogenic

0.63

Cadd

Pathogenic

Dann

Uncertain

1.0

Eigen

Pathogenic

0.68

Eigen_PC

Uncertain

0.53

FATHMM_MKL

Pathogenic

0.98

MutationTaster

Benign

1.0

A;A

Vest4

0.92

GERP RS

2.8

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

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