rs121908174

Positions:

• chr16-56514574-A-C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The ENST00000245157.11(BBS2):​c.224T>G​(p.Val75Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000684 in 1,461,770 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 (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: BBS2 ENST00000245157.11 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 9.10

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 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.943
• PP5: Variant 16-56514574-A-C is Pathogenic according to our data. Variant chr16-56514574-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 4569.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-56514574-A-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BBS2	NM_031885.5	c.224T>G	p.Val75Gly	missense_variant	2/17	ENST00000245157.11	NP_114091.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BBS2	ENST00000245157.11	c.224T>G	p.Val75Gly	missense_variant	2/17	1	NM_031885.5	ENSP00000245157	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251460 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135910

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: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000684 AC: 10 AN: 1461770 Hom.: 0 Cov.: 30 AF XY: 0.00000550 AC XY: 4 AN XY: 727200

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: 0.00000899

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000306 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bardet-Biedl syndrome 2 Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 05, 2023	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Apr 01, 2001	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Dec 08, 2017	- -

Bardet-Biedl syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 30, 2023	This sequence change replaces valine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 75 of the BBS2 protein (p.Val75Gly). This variant is present in population databases (rs121908174, gnomAD 0.0009%). This missense change has been observed in individuals with clinical features of Bardet-Biedl syndrome (PMID: 11285252, 28143435, 31456290). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 4569). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt BBS2 protein function with a positive predictive value of 80%. Experimental studies have shown that this missense change affects BBS2 function (PMID: 20498079). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, no assertion criteria provided	research	Sharon lab, Hadassah-Hebrew University Medical Center	Jun 23, 2019	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.80
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D;.
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.78	T;.
M_CAP	Uncertain	0.097	D
MetaRNN	Pathogenic	0.94	D;D
MetaSVM	Uncertain	0.27	D
MutationTaster	Benign	1.0	A;A
PrimateAI	Benign	0.46	T
PROVEAN	Pathogenic	-5.9	D;D
REVEL	Pathogenic	0.90
Sift	Uncertain	0.0010	D;D
Sift4G	Pathogenic	0.0010	D;D
Vest4		0.85
MutPred		0.83		Loss of sheet (P = 0.0181);Loss of sheet (P = 0.0181);
MVP		0.98
MPC		0.96
ClinPred		0.99	D
GERP RS		5.5
gMVP		0.91

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs121908174; hg19: chr16-56548486;