16-56511265-G-C

Position:

• chr16-56511265-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_031885.5(BBS2):​c.365C>G​(p.Ala122Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A122V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: BBS2 NM_031885.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.84

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 Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS2	NM_031885.5	c.365C>G	p.Ala122Gly	missense_variant	3/17	ENST00000245157.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS2	ENST00000245157.11	c.365C>G	p.Ala122Gly	missense_variant	3/17	1	NM_031885.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bardet-Biedl syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jun 21, 2021

Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. This variant has been observed in individual(s) with clinical features of BBS2-related conditions (Invitae). This variant is not present in population databases (ExAC no frequency). This sequence change replaces alanine with glycine at codon 122 of the BBS2 protein (p.Ala122Gly). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and glycine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.71	D;.
Eigen	Pathogenic	0.84
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;.
M_CAP	Uncertain	0.12	D
MetaRNN	Uncertain	0.65	D;D
MetaSVM	Uncertain	0.48	D
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.67	T
PROVEAN	Uncertain	-3.2	D;D
Sift	Uncertain	0.026	D;D
Sift4G	Uncertain	0.040	D;D
Vest4		0.65
MutPred		0.43		Gain of sheet (P = 0.0344);Gain of sheet (P = 0.0344);
MVP		0.88
MPC		0.39
ClinPred		0.98	D
GERP RS		5.9
gMVP		0.67

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr16-56545177;