rs1553933472

Variant names:

• chr4-121855547-C-CTT
• rs1553933472
• NM_176824.3:c.542_543insAA

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_176824.3(BBS7):​c.542_543insAA​(p.Met181IlefsTer14) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: BBS7 NM_176824.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.44

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]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 4-121855547-C-CTT is Pathogenic according to our data. Variant chr4-121855547-C-CTT is described in ClinVar as [Pathogenic]. Clinvar id is 531829.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BBS7	NM_176824.3	c.542_543insAA	p.Met181IlefsTer14	frameshift_variant	Exon 6 of 19	ENST00000264499.9	NP_789794.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BBS7	ENST00000264499.9	c.542_543insAA	p.Met181IlefsTer14	frameshift_variant	Exon 6 of 19	1	NM_176824.3	ENSP00000264499.4
BBS7	ENST00000506636.1	c.542_543insAA	p.Met181IlefsTer14	frameshift_variant	Exon 6 of 18	1		ENSP00000423626.1
BBS7	ENST00000508536.1	n.46_47insAA		non_coding_transcript_exon_variant	Exon 2 of 2	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bardet-Biedl syndrome Pathogenic:1

Feb 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Met181Ilefs*14) in the BBS7 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in BBS7 are known to be pathogenic (PMID: 12567324, 19402160, 21209035, 31196119). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with BBS7-related conditions. ClinVar contains an entry for this variant (Variation ID: 531829). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs1553933472; hg19: chr4-122776702;