1-197427873-G-T

Variant names:

• chr1-197427873-G-T
• rs776591659
• NM_201253.3:c.2548G>T

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_201253.3(CRB1):​c.2548G>T​(p.Gly850Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G850A) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CRB1 NM_201253.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.34
• Publications: 0 publications found

Genes affected

CRB1 (HGNC:2343): (crumbs cell polarity complex component 1) This gene encodes a protein which is similar to the Drosophila crumbs protein and localizes to the inner segment of mammalian photoreceptors. In Drosophila crumbs localizes to the stalk of the fly photoreceptor and may be a component of the molecular scaffold that controls proper development of polarity in the eye. Mutations in this gene are associated with a severe form of retinitis pigmentosa, RP12, and with Leber congenital amaurosis. Alternate splicing results in multiple transcript variants, some protein coding and some non-protein coding.[provided by RefSeq, Apr 2012]

CRB1 Gene-Disease associations (from GenCC):

• hereditary macular dystrophy

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• Leber congenital amaurosis 8

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Laboratory for Molecular Medicine
• retinitis pigmentosa 12

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• Leber congenital amaurosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• nanophthalmia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• pigmented paravenous retinochoroidal atrophy

  Inheritance: AD Classification: SUPPORTIVE, LIMITED Submitted by: G2P, Orphanet
• retinitis pigmentosa

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 13 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 7 uncertain in NM_201253.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-197427874-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 973927.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 168 curated pathogenic missense variants (we use a threshold of 10). The gene has 18 curated benign missense variants. Gene score misZ: -1.2832 (below the threshold of 3.09). Trascript score misZ: 0.62189 (below the threshold of 3.09). GenCC associations: The gene is linked to Leber congenital amaurosis 8, retinitis pigmentosa 12, pigmented paravenous retinochoroidal atrophy, hereditary macular dystrophy, retinitis pigmentosa, Leber congenital amaurosis, nanophthalmia.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.966
• PP5: Variant 1-197427873-G-T is Pathogenic according to our data. Variant chr1-197427873-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2943578.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_201253.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CRB1	NM_201253.3	MANE Select	c.2548G>T	p.Gly850Cys	missense	Exon 7 of 12	NP_957705.1
	CRB1	NM_001257965.2		c.2341G>T	p.Gly781Cys	missense	Exon 9 of 15	NP_001244894.1
	CRB1	NM_001193640.2		c.2212G>T	p.Gly738Cys	missense	Exon 5 of 10	NP_001180569.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CRB1	ENST00000367400.8	TSL:1 MANE Select	c.2548G>T	p.Gly850Cys	missense	Exon 7 of 12	ENSP00000356370.3
	CRB1	ENST00000638467.1	TSL:1	c.2548G>T	p.Gly850Cys	missense	Exon 7 of 11	ENSP00000491102.1
	CRB1	ENST00000367399.6	TSL:1	c.2212G>T	p.Gly738Cys	missense	Exon 5 of 10	ENSP00000356369.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinitis pigmentosa 12;C3151202:Leber congenital amaurosis 8 Pathogenic:1

Jan 24, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with cysteine, which is neutral and slightly polar, at codon 850 of the CRB1 protein (p.Gly850Cys). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CRB1-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt CRB1 protein function. This variant disrupts the p.Gly850 amino acid residue in CRB1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 15459956, 20591486, 20956273). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.71	D
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.90	D
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.3	M
PhyloP100		9.3
PrimateAI	Uncertain	0.53	T
PROVEAN	Pathogenic	-8.2	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0060	D
Polyphen		1.0	D
Vest4		0.81
MutPred		0.76		Loss of ubiquitination at K849 (P = 0.0935)
MVP		0.99
MPC		0.24
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.86
gMVP		0.96
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs776591659; hg19: chr1-197397003; COSMIC: COSV66329681; COSMIC: COSV66329681;