1-197427787-C-G

Variant names:

• chr1-197427787-C-G
• rs142857810
• NM_201253.3:c.2462C>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_201253.3(CRB1):​c.2462C>G​(p.Thr821Arg) variant causes a missense 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T821M) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CRB1 NM_201253.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.337
• 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: Uncertain_significance. The variant received 5 ACMG points.

• 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 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: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CRB1	NM_201253.3	c.2462C>G	p.Thr821Arg	missense_variant	Exon 7 of 12	ENST00000367400.8	NP_957705.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CRB1	ENST00000367400.8	c.2462C>G	p.Thr821Arg	missense_variant	Exon 7 of 12	1	NM_201253.3	ENSP00000356370.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Feb 24, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with arginine, which is basic and polar, at codon 821 of the CRB1 protein (p.Thr821Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Leber congenital amaurosis (PMID: 26047050). 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: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C15"). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.077
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Benign	-0.42
CADD	Uncertain	24
DANN	Benign	0.93
DEOGEN2	Uncertain	0.43	T;.;D;.;T
Eigen	Benign	-0.46
Eigen_PC	Benign	-0.59
LIST_S2	Benign	0.66	T;.;T;T;T
M_CAP	Pathogenic	0.56	D
MetaRNN	Uncertain	0.53	D;D;D;D;D
MetaSVM	Benign	-0.52	T
MutationAssessor	Benign	0.0	.;M;M;.;.
PhyloP100		-0.34
PrimateAI	Benign	0.28	T
PROVEAN	Uncertain	-2.4	N;.;N;N;N
Sift	Benign	0.54	T;.;T;T;T
Sift4G	Benign	0.42	T;.;T;T;D
Vest4		0.71
ClinPred		0.40	T
GERP RS		4.0
Varity_R		0.096
gMVP		0.76
Mutation Taster		=8/92	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.95		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.95		Position offset: 1

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

Other links and lift over

dbSNP: rs142857810; hg19: chr1-197396917;