16-56514557-C-T

Variant names:

• chr16-56514557-C-T
• rs750506474
• NM_031885.5:c.241G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Strong

The NM_031885.5(BBS2):​c.241G>A​(p.Gly81Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,840 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G81V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: BBS2 NM_031885.5 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.72
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• Bardet-Biedl syndrome 2

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae), Myriad Women’s Health
• ciliopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• retinitis pigmentosa 74

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• retinitis pigmentosa

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Bardet-Biedl syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-56514557-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 557198.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.942

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BBS2	NM_031885.5	c.241G>A	p.Gly81Ser	missense_variant	Exon 2 of 17	ENST00000245157.11	NP_114091.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BBS2	ENST00000245157.11	c.241G>A	p.Gly81Ser	missense_variant	Exon 2 of 17	1	NM_031885.5	ENSP00000245157.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461840 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727226

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111960

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.20
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.69	D;.
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.94	D;.
M_CAP	Benign	0.061	D
MetaRNN	Pathogenic	0.94	D;D
MetaSVM	Pathogenic	0.83	D
PhyloP100		7.7
PrimateAI	Uncertain	0.70	T
PROVEAN	Pathogenic	-4.8	D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0090	D;D
Sift4G	Uncertain	0.017	D;D
Vest4		0.90
MutPred		0.75		Gain of catalytic residue at G81 (P = 0.0516);Gain of catalytic residue at G81 (P = 0.0516);
MVP		0.90
MPC		0.89
ClinPred		0.99	D
GERP RS		5.4
gMVP		0.84
Mutation Taster		=22/78	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs750506474; hg19: chr16-56548469;