rs142857810

Positions:

• chr1-197427787-C-G
• chr1-197427787-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 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

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a domain Laminin G-like 2 (size 171) in uniprot entity CRUM1_HUMAN there are 95 pathogenic changes around while only 6 benign (94%) 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 chr1-197427787-C-T is described in Lovd as [Pathogenic].
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CRB1	NM_201253.3	c.2462C>G	p.Thr821Arg	missense_variant	7/12	ENST00000367400.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CRB1	ENST00000367400.8	c.2462C>G	p.Thr821Arg	missense_variant	7/12	1	NM_201253.3	P1

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Feb 24, 2022

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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a 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: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C15"). This missense change has been observed in individual(s) with Leber congenital amaurosis (PMID: 26047050). This variant is not present in population databases (gnomAD no frequency). 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). -

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
FATHMM_MKL	Benign	0.11	N
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	Uncertain	2.5	.;M;M;.;.
MutationTaster	Benign	1.0	N;N;N;N;N;N
PrimateAI	Benign	0.28	T
PROVEAN	Uncertain	-2.4	N;.;N;N;N
REVEL	Uncertain	0.36
Sift	Benign	0.54	T;.;T;T;T
Sift4G	Benign	0.42	T;.;T;T;D
Polyphen		0.99	D;.;D;D;.
Vest4		0.71
MutPred		0.79		.;Loss of methylation at K826 (P = 0.0707);Loss of methylation at K826 (P = 0.0707);.;.;
MVP		0.81
MPC		0.19
ClinPred		0.40	T
GERP RS		4.0
Varity_R		0.096
gMVP		0.76

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr1-197396917;