rs746875134

chr11-66523577-G-Achr11-66523577-G-Cchr11-66523577-G-T

Variant summary

Our verdict is Pathogenic. Variant got 22 ACMG points: 22P and 0B. PVS1 PM2 PP3_Strong PP5_Very_Strong

The NM_024649.5(BBS1):c.951+1G>A variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000889 in 1,461,856 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000089 (0 hom.)
• Consequence: BBS1 NM_024649.5 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 8.77

Genes affected

BBS1 (HGNC:966): (Bardet-Biedl syndrome 1) Mutations in this gene have been observed in patients with the major form (type 1) of Bardet-Biedl syndrome. The encoded protein may play a role in eye, limb, cardiac and reproductive system development. [provided by RefSeq, Jul 2008]

ZDHHC24 (HGNC:27387): (zinc finger DHHC-type containing 24) Predicted to enable protein-cysteine S-palmitoyltransferase activity. Predicted to be involved in peptidyl-L-cysteine S-palmitoylation and protein targeting to membrane. Predicted to be integral component of membrane. Predicted to be active in Golgi apparatus and endoplasmic reticulum. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Pathogenic. Variant got 22 ACMG points.

• PVS1: Splicing variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 11-66523577-G-A is Pathogenic according to our data. Variant chr11-66523577-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370919.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-66523577-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS1	NM_024649.5	c.951+1G>A		splice_donor_variant		ENST00000318312.12

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS1	ENST00000318312.12	c.951+1G>A		splice_donor_variant		1	NM_024649.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251330 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135862

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000889 AC: 13 AN: 1461856 Hom.: 0 Cov.: 31 AF XY: 0.0000110 AC XY: 8 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000580

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000629

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bardet-Biedl syndrome 1 Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Centre for Mendelian Genomics, University Medical Centre Ljubljana	Nov 15, 2018	This variant was classified as: Pathogenic. The following ACMG criteria were applied in classifying this variant: PVS1,PM2,PP4. This variant was detected in homozygous state. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	May 20, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	3billion	Sep 01, 2022	The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: <0.001%). It is predicted to alter splicing, resulting in a loss or disruption of normal protein function. Multiple pathogenic loss-of-function variants are reported downstream of the variant. The variant has been reported to be in trans with a pathogenic variant as either compound heterozygous or homozygous in at least one similarly affected unrelated individual (3billion dataset). The variant has been reported at least twice as pathogenic with clinical assertions and evidence for the classification (ClinVar ID: VCV000370919 / 3billion dataset). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 04, 2023	- -

Bardet-Biedl syndrome Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 17, 2020	Variant summary: BBS1 c.951+1G>A is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes a 5' splicing donor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 8e-06 in 251330 control chromosomes. c.951+1G>A has been reported in the literature in multiple individuals affected with features of Bardet-Biedl Syndrome (example, Fauser_2003, Redin_2012, Forsyth_2017, Komazec_2019). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic (n=3)/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Aug 04, 2023	For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 370919). Disruption of this splice site has been observed in individuals with Bardet-Biedl syndrome (PMID: 12920096, 27659767, 30614526). This variant is present in population databases (rs746875134, gnomAD 0.003%). This sequence change affects a donor splice site in intron 10 of the BBS1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in BBS1 are known to be pathogenic (PMID: 12118255, 21520335, 27032803). -
Pathogenic, no assertion criteria provided	provider interpretation	Laboratory of Medical Genetics (UMR_S 1112), INSERM/Strasbourg University	Sep 15, 2018	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 13, 2022

Observed with a second variant in the BBS1 gene (phase unknown) in a patient with Bardet-Biedl syndrome (Fauser et al., 2003); Canonical splice site variant predicted to result in a null allele in a gene for which loss of function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 30614526, 30259503, 12920096, 22773737, 27659767) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.41
Cadd	Pathogenic	27
Dann	Uncertain	0.99
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D;D
GERP RS		5.3

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.76		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.76		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs746875134; hg19: chr11-66291048;