Genetic Variant CTC1:p.Ala227Gly (chr17-8237487-G-C) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2PM5

The NM_025099.6(CTC1):c.680C>G(p.Ala227Gly) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,874 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. A227V) has been classified as Pathogenic.

Frequency

Genomes: not found (cov: 29)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

CTC1
NM_025099.6 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 4.49

Publications

0 publications found

Variant links:

Genes affected

CTC1 (HGNC:26169): (CST telomere replication complex component 1) This gene encodes a component of the CST complex. This complex plays an essential role in protecting telomeres from degradation. This protein also forms a heterodimer with the CST complex subunit STN1 to form the enzyme alpha accessory factor. This enzyme regulates DNA replication. Mutations in this gene are the cause of cerebroretinal microangiopathy with calcifications and cysts. Alternate splicing results in both coding and non-coding variants. [provided by RefSeq, Mar 2012]

CTC1 Gene-Disease associations (from GenCC):

cerebroretinal microangiopathy with calcifications and cysts 1
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia, Ambry Genetics, G2P
dyskeratosis congenita
Inheritance: AR, AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, Orphanet
Coats plus syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

CTC1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr17-8237487-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 31004.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CTC1	NM_025099.6 link	c.680C>G	p.Ala227Gly	missense_variant	Exon 5 of 23	ENST00000651323.1	NP_079375.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CTC1	ENST00000651323.1 link	c.680C>G	p.Ala227Gly	missense_variant	Exon 5 of 23		NM_025099.6	ENSP00000498499.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461874

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727242

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:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111994

Other (OTH)

AF:

0.00

AC:

AN:

60396

⚠️ 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

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.30

BayesDel_addAF

Uncertain

0.094

BayesDel_noAF

Benign

-0.10

CADD

Uncertain

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.40

Eigen

Uncertain

0.59

Eigen_PC

Uncertain

0.56

FATHMM_MKL

Benign

0.75

LIST_S2

Benign

0.77

M_CAP

Benign

0.062

MetaRNN

Uncertain

0.50

MetaSVM

Uncertain

0.52

MutationAssessor

Uncertain

2.6

PhyloP100

4.5

PrimateAI

Benign

0.45

PROVEAN

Benign

-1.1

REVEL

Uncertain

0.42

Sift

Benign

0.16

Sift4G

Benign

0.19

Polyphen

1.0

Vest4

0.48

MutPred

0.39

Gain of sheet (P = 0.0344);

MVP

0.83

MPC

0.56

ClinPred

0.92

GERP RS

4.8

Varity_R

0.19

gMVP

0.51

Mutation Taster

=92/8

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.22

Details are displayed if max score is > 0.2

DS_AL_spliceai

0.22

Position offset: 32

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

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over