Genetic Variant CR1:p.Ile2065Phe (chr1-207609586-A-T) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_000651.6(CR1):c.6193A>T(p.Ile2065Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,638 control chromosomes in the GnomAD database, with no homozygous occurrence. 13/20 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I2065V) has been classified as Benign.

Frequency

Genomes: not found (cov: 31)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

CR1
NM_000651.6 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 1.96

Publications

0 publications found

Variant links:

Genes affected

CR1 (HGNC:2334): (complement C3b/C4b receptor 1 (Knops blood group)) This gene is a member of the receptors of complement activation (RCA) family and is located in the 'cluster RCA' region of chromosome 1. The genome is polymorphic at this locus with allele-specific splice variants encoding different isoforms, based on the presence/absence of long homologous repeats (LHRs). The gene encodes a monomeric single-pass type I membrane glycoprotein found on erythrocytes, leukocytes, glomerular podocytes, and splenic follicular dendritic cells. The Knops blood group system is a system of antigens located on this protein. The protein mediates cellular binding to particles and immune complexes that have activated complement. Decreases in expression of this protein and/or mutations in this gene have been associated with gallbladder carcinomas, mesangiocapillary glomerulonephritis, systemic lupus erythematosus, sarcoidosis and Alzheimer's disease. Mutations in this gene have also been associated with a reduction in Plasmodium falciparum rosetting, conferring protection against severe malaria. [provided by RefSeq, May 2020]

CR1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CR1	NM_000651.6 link	c.6193A>T	p.Ile2065Phe	missense_variant	Exon 37 of 47	ENST00000367049.9	NP_000642.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CR1	ENST00000367049.9 link	c.6193A>T	p.Ile2065Phe	missense_variant	Exon 37 of 47	5	NM_000651.6	ENSP00000356016.4

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.85e-7

AC:

AN:

1460638

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726504

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33468

American (AMR)

AF:

0.00

AC:

AN:

44476

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26102

East Asian (EAS)

AF:

0.00

AC:

AN:

39666

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86142

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53342

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111322

Other (OTH)

AF:

0.00

AC:

AN:

60352

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.29

BayesDel_addAF

Benign

-0.032

BayesDel_noAF

Benign

-0.28

CADD

Benign

(source)

DANN

Benign

0.81

DEOGEN2

Benign

0.0

.;.;.;.;.

Eigen

Benign

-0.56

Eigen_PC

Benign

-0.66

FATHMM_MKL

Benign

0.12

LIST_S2

Benign

0.0

.;.;.;T;T

M_CAP

Benign

0.024

MetaRNN

Uncertain

0.50

D;D;D;D;D

MetaSVM

Benign

-0.40

MutationAssessor

Benign

0.0

.;.;.;.;.

PhyloP100

2.0

PrimateAI

Uncertain

0.52

PROVEAN

Uncertain

-3.2

D;D;D;D;D

REVEL

Benign

0.18

Sift

Uncertain

0.0060

D;D;D;D;D

Sift4G

Uncertain

0.010

D;D;D;D;D

Vest4

0.27

ClinPred

0.19

GERP RS

2.5

gMVP

0.56

Mutation Taster

=96/4

polymorphism

(source)

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over