rs770258677

Variant summary

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

The NM_031885.5(BBS2):c.661del(p.Leu221PhefsTer25) variant causes a frameshift change. The variant allele was found at a frequency of 0.000013 in 1,613,972 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

BBS2
NM_031885.5 frameshift

Scores

Not classified

Clinical Significance

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

Conservation

PhyloP100: 5.69

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 16-56506175-AG-A is Pathogenic according to our data. Variant chr16-56506175-AG-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 208564.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-56506175-AG-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.661del	p.Leu221PhefsTer25	frameshift_variant	6/17	ENST00000245157.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS2	ENST00000245157.11 linkuse as main transcript	c.661del	p.Leu221PhefsTer25	frameshift_variant	6/17	1	NM_031885.5	P1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152254

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:

0.0000942

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000199

AC:

AN:

251270

Hom.:

AF XY:

0.0000221

AC XY:

AN XY:

135808

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:

0.000185

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000137

AC:

AN:

1461718

Hom.:

Cov.:

AF XY:

0.0000110

AC XY:

AN XY:

727150

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:

0.000169

Gnomad4 NFE exome

AF:

0.00000989

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152254

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74378

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:

0.0000942

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000868

Hom.:

Bravo

AF:

0.00000378

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:4

Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Mar 15, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Jan 20, 2015	The p.Leu221PhefsX25 variant in BBS2 has been reported in 1 homozygous and 2 compound heterozygous individuals with Bardet-Biedl syndrome (BBS; Hjortshøj 2010). This variant has been identified in 0.03% (2/6592) of European (Finnish) chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant is predicted to cause a frameshift, which alters the protein’s amino acid sequence beginning at position 221 and leads to a premature termination codon 25 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Complete loss of BBS2 function is an established disease mechanism in BBS. In summary, this variant meets our criteria to be classified as pathogenic for BBS in an autosomal recessive manner. -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Apr 24, 2023	- -

Bardet-Biedl syndrome

Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 03, 2024	This sequence change creates a premature translational stop signal (p.Leu221Phefs*25) 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 (rs770258677, gnomAD 0.02%). This premature translational stop signal has been observed in individuals with Bardet-Biedl syndrome (PMID: 20120035). ClinVar contains an entry for this variant (Variation ID: 208564). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jun 06, 2022	Variant summary: BBS2 c.661delC (p.Leu221PhefsX25) 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 2e-05 in 251270 control chromosomes (gnomAD). c.661delC has been reported in the literature in both homozygous and compound heterozygous individuals affected with Bardet-Biedl Syndrome (Hjortshoj_2010). 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. Six ClinVar submitters have assessed the variant since 2014: one classified the variant as likely pathogenic and five classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Inborn genetic diseases

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 23, 2021

The c.661delC (p.L221Ffs*25) alteration, located in exon 6 (coding exon 6) of the BBS2 gene, consists of a deletion of one nucleotide at position 661, causing a translational frameshift with a predicted alternate stop codon after 25 amino acids. This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. Based on data from gnomAD, the BBS2 c.661delC alteration has an overall frequency of <0.01% (7/282674) total alleles studied. The highest observed frequency was 0.02% (5/25080) of European (Finnish) alleles. This pathogenic alteration has been reported in multiple unrelated individuals with Bardet-Biedl syndrome (BBS) in the homozygous state or in conjunction with a second pathogenic BBS2 allele (Hjortshøj, 2010). Based on the available evidence, this alteration is classified as pathogenic. -

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Oct 23, 2020

- -

Retinitis pigmentosa

Pathogenic:1

Pathogenic, no assertion criteria provided

research

Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet

Apr 01, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

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