rs761403504

chr4-121853086-C-Achr4-121853086-C-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2 PM5 PP3_Strong PP5_Moderate

The NM_176824.3(BBS7):c.719G>T(p.Gly240Val) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,460,624 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 Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G240D) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: BBS7 NM_176824.3 missense, splice_region
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.65

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 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr4-121853086-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 522733.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=1}.
• 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 4-121853086-C-A is Pathogenic according to our data. Variant chr4-121853086-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 2418923.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS7	NM_176824.3	c.719G>T	p.Gly240Val	missense_variant, splice_region_variant	8/19	ENST00000264499.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS7	ENST00000264499.9	c.719G>T	p.Gly240Val	missense_variant, splice_region_variant	8/19	1	NM_176824.3	P1
BBS7	ENST00000506636.1	c.719G>T	p.Gly240Val	missense_variant, splice_region_variant	8/18	1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251052 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135720

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

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: 0.00000205 AC: 3 AN: 1460624 Hom.: 0 Cov.: 30 AF XY: 0.00000413 AC XY: 3 AN XY: 726698

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bardet-Biedl syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jun 08, 2022

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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This missense change has been observed in individual(s) with Bardet-Biedl syndrome (PMID: 31469663). It has also been observed to segregate with disease in related individuals. This variant is present in population databases (rs761403504, gnomAD 0.003%). This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 240 of the BBS7 protein (p.Gly240Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.30
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Pathogenic	0.21
Cadd	Pathogenic	35
Dann	Uncertain	1.0
DEOGEN2	Benign	0.39	T;.
Eigen	Pathogenic	0.82
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.87	D;D
MetaSVM	Uncertain	0.13	D
MutationAssessor	Pathogenic	3.0	M;M
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.50	T
PROVEAN	Uncertain	-3.7	D;D
REVEL	Pathogenic	0.65
Sift	Uncertain	0.012	D;D
Sift4G	Uncertain	0.013	D;D
Polyphen		1.0	D;.
Vest4		0.94
MutPred		0.47		Loss of ubiquitination at K236 (P = 0.0583);Loss of ubiquitination at K236 (P = 0.0583);
MVP		0.97
MPC		0.74
ClinPred		0.98	D
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.69
gMVP		0.88

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.57		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.57		Position offset: -19
DS_AL_spliceai		0.34		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs761403504; hg19: chr4-122774241;