rs764164384

chr16-56502799-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_031885.5(BBS2):c.814C>T(p.Arg272Ter) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,872 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 Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R272R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: BBS2 NM_031885.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:11
• Conservation: PhyloP100: 8.10

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]

ACMG classification

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 16-56502799-G-A is Pathogenic according to our data. Variant chr16-56502799-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 552219.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-56502799-G-A is described in Lovd as [Pathogenic]. Variant chr16-56502799-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS2	NM_031885.5	c.814C>T	p.Arg272Ter	stop_gained	8/17	ENST00000245157.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS2	ENST00000245157.11	c.814C>T	p.Arg272Ter	stop_gained	8/17	1	NM_031885.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251294 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135844

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.0000993

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461872 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727234

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.0000383

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:11

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bardet-Biedl syndrome 2 Pathogenic:4

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Sep 07, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	May 30, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Sep 08, 2017	Variant summary: The BBS2 c.814C>T (p.Arg272X) variant results in a premature termination codon, predicted to cause a truncated or absent BBS2 protein due to nonsense mediated decay, which are commonly known mechanisms for disease. A truncation downstream of this position, c.823C>T (p.Arg275X) has been classified as pathogenic by our laboratory. This variant was found in 3/246118 control chromosomes at a frequency of 0.0000122, which does not exceed the estimated maximal expected allele frequency of a pathogenic BBS2 variant (0.0008452). Multiple publications have cited the variant in homozygous affected individuals. The variant of interest has not, to our knowledge, been cited and classified by clinical diagnostic laboratories. Taken together, this variant is classified as pathogenic. -

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Feb 03, 2022	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: 25525159, 28559085, 25780760, 31196119, 11285252) -
Pathogenic, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -

Bardet-Biedl syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	research	SN ONGC Dept of Genetics and Molecular biology Vision Research Foundation	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jun 26, 2023	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 552219). This premature translational stop signal has been observed in individual(s) with Bardet-Biedl syndrome (PMID: 11285252, 28559085). This variant is present in population databases (rs764164384, gnomAD 0.01%). This sequence change creates a premature translational stop signal (p.Arg272*) 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). -

Retinal dystrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

research

Dept Of Ophthalmology, Nagoya University

Oct 01, 2023

- -

Bardet-Biedl syndrome 2;C4225281:Retinitis pigmentosa 74 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Apr 03, 2022

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.61	D
BayesDel_noAF	Pathogenic	0.63
Cadd	Pathogenic	39
Dann	Uncertain	1.0
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.98	D
MutationTaster	Benign	1.0	A;A
Vest4		0.83
GERP RS		4.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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

Other links and lift over

dbSNP: rs764164384; hg19: chr16-56536711;