17-8224925-C-G

Variant summary

Our verdict is Benign. Variant got -14 ACMG points: 0P and 14B. BP4_Strong BP6_Moderate BS1 BS2

The NM_025099.6(CTC1):c.*3255G>C variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00234 in 152,324 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).

• Frequency:
  • Genomes: 𝑓 0.0023 (2 hom., cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CTC1 NM_025099.6 3_prime_UTR
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: -1.44

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]

ACMG classification

Verdict is Benign. Variant got -14 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.95).
• BP6: Variant 17-8224925-C-G is Benign according to our data. Variant chr17-8224925-C-G is described in ClinVar as [Likely_benign]. Clinvar id is 892092.Status of the report is criteria_provided_single_submitter, 1 stars.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00234 (357/152324) while in subpopulation AFR AF= 0.00794 (330/41568). AF 95% confidence interval is 0.00723. There are 2 homozygotes in gnomad4. There are 167 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 2 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CTC1	NM_025099.6	c.*3255G>C		3_prime_UTR_variant	23/23	ENST00000651323.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CTC1	ENST00000651323.1	c.*3255G>C		3_prime_UTR_variant	23/23		NM_025099.6	P1

Frequencies

GnomAD3 genomes AF: 0.00234 AC: 356 AN: 152206 Hom.: 2 Cov.: 32

Gnomad AFR AF: 0.00794

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000769

Gnomad SAS AF: 0.000620

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000103

Gnomad OTH AF: 0.00144

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 38 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 26

Gnomad4 ASJ exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00234 AC: 357 AN: 152324 Hom.: 2 Cov.: 32 AF XY: 0.00224 AC XY: 167 AN XY: 74484

Gnomad4 AFR AF: 0.00794

Gnomad4 AMR AF: 0.000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000771

Gnomad4 SAS AF: 0.000621

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000103

Gnomad4 OTH AF: 0.00142

Alfa AF: 0.0000697 Hom.: 0

Bravo AF: 0.00251

Asia WGS AF: 0.00115 AC: 4 AN: 3478

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Dyskeratosis congenita Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.95
Cadd	Benign	0.083
Dann	Benign	0.37

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

LitVar

Other links and lift over

dbSNP: rs8072663; hg19: chr17-8128243;