NM_152384.3:c.522+3A>G

Variant names:

• chr2-169493012-A-G
• rs587777828
• NM_152384.3:c.522+3A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Moderate PP5_Moderate

The NM_152384.3(BBS5):​c.522+3A>G variant causes a splice region, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,172 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: BBS5 NM_152384.3 splice_region, intron
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 8.45
• Publications: 0 publications found

Genes affected

BBS5 (HGNC:970): (Bardet-Biedl syndrome 5) This gene encodes a protein that has been directly linked to Bardet-Biedl syndrome. The primary features of this syndrome include retinal dystrophy, obesity, polydactyly, renal abnormalities and learning disabilities. Experimentation in non-human eukaryotes suggests that this gene is expressed in ciliated cells and that it is required for the formation of cilia. Alternate transcriptional splice variants have been observed but have not been fully characterized. [provided by RefSeq, Jul 2008]

BBS5 Gene-Disease associations (from GenCC):

• Bardet-Biedl syndrome 5

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp, Ambry Genetics, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae)
• Bardet-Biedl syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000251569 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 2-169493012-A-G is Pathogenic according to our data. Variant chr2-169493012-A-G is described in ClinVar as Pathogenic. ClinVar VariationId is 6157.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BBS5	NM_152384.3	c.522+3A>G		splice_region_variant, intron_variant	Intron 6 of 11	ENST00000295240.8	NP_689597.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BBS5	ENST00000295240.8	c.522+3A>G		splice_region_variant, intron_variant	Intron 6 of 11	1	NM_152384.3	ENSP00000295240.3
ENSG00000251569	ENST00000513963.1	c.522+3A>G		splice_region_variant, intron_variant	Intron 6 of 15	2		ENSP00000424363.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461172 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726936

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33456

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26108

East Asian (EAS) AF: 0.00 AC: 0 AN: 39560

South Asian (SAS) AF: 0.00 AC: 0 AN: 86238

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53280

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5748

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111694

Other (OTH) AF: 0.00 AC: 0 AN: 60368

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Bardet-Biedl syndrome Pathogenic:1

Oct 28, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: BBS5 c.522+3A>G alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: Three predict the variant abolishes/weakens a 5' splicing donor site. Experimental evidence supports these predictions, demonstrating this variant affects mRNA splicing (Li_2004). The variant was absent in 251280 control chromosomes (gnomAD). c.522+3A>G has been reported in the literature as a homozygous genotype in multiple individuals affected with Bardet-Biedl Syndrome, segregating with disease within families (example Li_2004, Webb_2009). These data indicate that the variant is very likely to be associated with disease. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as pathogenic. -

Bardet-Biedl syndrome 5 Pathogenic:1

May 14, 2004

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.23
CADD	Benign	21
DANN	Benign	0.96
PhyloP100		8.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Mutation Taster		=5/95	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.98
SpliceAI score (max)		0.83		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.28		Position offset: 40
DS_DL_spliceai		0.83		Position offset: -3

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

Other links and lift over

dbSNP: rs587777828; hg19: chr2-170349522;