Genetic Variant BBS2:p.Arg315Trp (chr16-56502454-G-A) – ACMG Classification: Pathogenic (16 pts)

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PM1PM5PP3_StrongPP5_Very_Strong

The NM_031885.5(BBS2):c.943C>T(p.Arg315Trp) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,613,986 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R315Q) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

BBS2
NM_031885.5 missense, splice_region

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8U:1

Conservation

PhyloP100: 7.76

Publications

10 publications found

Variant links:

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: Ambry Genetics, G2P, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Myriad Women’s Health
BBS2-related 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

BBS2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 16 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 5 uncertain in NM_031885.5

PM5

Other missense variant is known to change same aminoacid residue: Variant chr16-56502453-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 555022.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.943

PP5

Variant 16-56502454-G-A is Pathogenic according to our data. Variant chr16-56502454-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 4573.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_031885.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
BBS2	NM_031885.5	MANE Select	c.943C>T	p.Arg315Trp	missense splice_region	Exon 9 of 17	NP_114091.4
BBS2	NM_001377456.1		c.943C>T	p.Arg315Trp	missense splice_region	Exon 9 of 18	NP_001364385.1	Q9BXC9
BBS2	NR_165293.1		n.1105C>T		splice_region non_coding_transcript_exon	Exon 9 of 17

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
BBS2	ENST00000245157.11	TSL:1 MANE Select	c.943C>T	p.Arg315Trp	missense splice_region	Exon 9 of 17	ENSP00000245157.5	Q9BXC9
BBS2	ENST00000565781.6	TSL:1	n.1173C>T		non_coding_transcript_exon	Exon 8 of 12
BBS2	ENST00000682188.1		c.943C>T	p.Arg315Trp	missense splice_region	Exon 9 of 17	ENSP00000507655.1	A0A804HJV0

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152104

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000159

AC:

AN:

251330

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.0000578

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000144

AC:

AN:

1461882

Hom.:

Cov.:

AF XY:

0.0000193

AC XY:

AN XY:

727238

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.0000447

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53408

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000162

AC:

AN:

1112012

Other (OTH)

AF:

0.00

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.454

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152104

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74304

show subpopulations

African (AFR)

AF:

0.0000483

AC:

AN:

41406

American (AMR)

AF:

0.00

AC:

AN:

15274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10606

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

68008

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.563

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000180

Hom.:

Bravo

AF:

0.0000227

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.00

AC:

ExAC

AF:

0.0000165

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.0000593

ClinVar

ClinVar submissions

Significance:Pathogenic/Likely pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Bardet-Biedl syndrome 2 (3)

Autosomal recessive retinitis pigmentosa (1)

Bardet-Biedl syndrome (1)

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

Bardet-biedl syndrome 2/4, digenic (1)

Retinal dystrophy (1)

Retinitis pigmentosa 74 (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.56

BayesDel_addAF

Pathogenic

0.38

BayesDel_noAF

Pathogenic

0.49

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.75

Eigen

Pathogenic

0.83

Eigen_PC

Pathogenic

0.79

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.99

M_CAP

Uncertain

0.28

MetaRNN

Pathogenic

0.94

MetaSVM

Pathogenic

0.94

PhyloP100

7.8

PrimateAI

Uncertain

0.65

PROVEAN

Pathogenic

-6.7

REVEL

Pathogenic

0.92

Sift

Uncertain

0.0010

Sift4G

Pathogenic

0.0010

Vest4

0.86

MVP

0.95

MPC

0.92

ClinPred

0.97

GERP RS

4.9

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

gMVP

0.91

Mutation Taster

=19/81

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over