rs863224529

Variant names:

• chr4-121828172-TGC-A
• rs863224529
• NM_176824.3:c.1986_1988delGCAinsT

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Moderate PM2 PP2 PP5

The NM_176824.3(BBS7):​c.1986_1988delGCAinsT​(p.Lys662AsnfsTer6) variant causes a frameshift, 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 Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: BBS7 NM_176824.3 frameshift, missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:1
• Conservation: PhyloP100: 9.83
• Publications: 0 publications found

Genes affected

BBS7 (HGNC:18758): (Bardet-Biedl syndrome 7) This gene encodes one of eight proteins that form the BBSome complex containing BBS1, BBS2, BBS4, BBS5, BBS7, BBS8, BBS9 and BBIP10. The BBSome complex is believed to recruit Rab8(GTP) to the primary cilium and promote ciliogenesis. The BBSome complex assembly is mediated by a complex composed of three chaperonin-like BBS proteins (BBS6, BBS10, and BBS12) and CCT/TRiC family chaperonins. Mutations in this gene are implicated in Bardet-Biedl syndrome, a genetic disorder whose symptoms include obesity, retinal degeneration, polydactyly and nephropathy; however, mutations in this gene and the BBS8 gene are thought to play a minor role and mutations in chaperonin-like BBS genes are found to be a major contributor to disease development in a multiethnic Bardet-Biedl syndrome patient population. Two transcript variants encoding distinct isoforms have been identified for this gene.[provided by RefSeq, Oct 2014]

BBS7 Gene-Disease associations (from GenCC):

• Bardet-Biedl syndrome 7

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• BBS7-related ciliopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• Bardet-Biedl syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

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

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0754 CDS is truncated, and there are 2 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 11 curated pathogenic missense variants (we use a threshold of 10). The gene has 1 curated benign missense variants. Gene score misZ: 1.2326 (below the threshold of 3.09). Trascript score misZ: 1.7868 (below the threshold of 3.09). GenCC associations: The gene is linked to Bardet-Biedl syndrome, Bardet-Biedl syndrome 7, BBS7-related ciliopathy.
• PP5: Variant 4-121828172-TGC-A is Pathogenic according to our data. Variant chr4-121828172-TGC-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 216137.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_176824.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BBS7	NM_176824.3	MANE Select	c.1986_1988delGCAinsT	p.Lys662AsnfsTer6	frameshift missense	Exon 18 of 19	NP_789794.1	Q8IWZ6-1
	BBS7	NM_018190.4		c.1986_1988delGCAinsT	p.Lys662AsnfsTer6	frameshift missense	Exon 18 of 18	NP_060660.2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BBS7	ENST00000264499.9	TSL:1 MANE Select	c.1986_1988delGCAinsT	p.Lys662AsnfsTer6	frameshift missense	Exon 18 of 19	ENSP00000264499.4	Q8IWZ6-1
	BBS7	ENST00000506636.1	TSL:1	c.1986_1988delGCAinsT	p.Lys662AsnfsTer6	frameshift missense	Exon 18 of 18	ENSP00000423626.1	Q8IWZ6-2
	BBS7	ENST00000888033.1		c.2034_2036delGCAinsT	p.Lys678AsnfsTer6	frameshift missense	Exon 18 of 19	ENSP00000558092.1

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
1	-	-	Bardet-Biedl syndrome (1)
1	-	-	Bardet-Biedl syndrome 7 (1)
1	-	-	BBS7-related disorder (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.8

Splicing

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

Other links and lift over

dbSNP: rs863224529; hg19: chr4-122749327;