Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2PP3_StrongPP5_Very_Strong
The NM_031885.5(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 (★★).
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]
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].
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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Apr 01, 2001
OMIM
Significance: Pathogenic
Review Status: no assertion criteria provided
Collection Method: literature only
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Dec 08, 2017
Counsyl
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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Bardet-Biedl syndrome Pathogenic:2
Dec 30, 2023
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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. -
Jun 23, 2019
Sharon lab, Hadassah-Hebrew University Medical Center