Is CTC1 p.Ala6= (c.18C>G) pathogenic?

CTC1 p.Ala6= (c.18C>G) is classified Likely benign in CTC1 (ClinVar, Multiple submitters, 2 submitters; last evaluated 2025-06-29). Very rare (popmax 0.00805%, afr); Associated with dyskeratosis congenita.

What condition is associated with CTC1 p.Ala6= (c.18C>G)?

CTC1 p.Ala6= (c.18C>G) is associated with dyskeratosis congenita (ClinVar).

How common is CTC1 p.Ala6= (c.18C>G) in the general population?

CTC1 p.Ala6= (c.18C>G) is very rare (popmax 0.00805%, afr) (gnomAD).

How is Dyskeratosis congenita inherited?

Typically Autosomal dominant, Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

CTC1 p.Ala6=

c.18C>G · rs377706974 · VCV1155574

Likely benign Multiple submitters

Classification

Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

gnomAD v4.1

Rare

very rare (popmax 0.00805%, afr)

Conditions

dyskeratosis congenita

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.27	GERP -4.7
Overall
CADD	2.931	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00805% African / African-American · 6/74,540 alleles

Filtering AF 0.00349% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00239%

Overall 0.00112% 18/1,606,952 alleles · very rare

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.00805%	12,423
Admixed American	0.00168%	59,598
Remaining individualsnot grpmax-eligible	0.00161%	61,982
European (non-Finnish)	0.00085%	117,688

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: CTC1
Protein: p.Ala6=
Coding: c.18C>G
MANE Select: NM_025099
dbSNP: rs377706974
Type: single nucleotide variant
Location: chr17:8248019 (GRCh38)
Gene constraint: LOEUF 0.776 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 78.01 · 7 PDB

Full CTC1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

dyskeratosis congenita — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Dyskeratosis congenita (Orphanet):

Inheritance: Autosomal dominant, Autosomal recessive, X-linked recessive
Onset: Adolescent, Adult, Childhood, Infancy, Neonatal
Prevalence: 1-9 / 1 000 000 (Europe)

Similar variants

CTC1 p.Ala6Ser Uncertain significance ★★ ⚠ same residue
CTC1 p.Ala6Val Conflicting classifications of pathogenicity ★ ⚠ same residue
CTC1 c.1617+5G>T Pathogenic/Likely pathogenic ★★ same condition
CTC1 c.1818+1G>A Likely pathogenic ★★ same condition
CTC1 c.2386-1G>A Likely pathogenic ★★ same condition
CTC1 c.2758+1G>T Pathogenic/Likely pathogenic ★★ same condition
CTC1 c.3221+1G>A Likely pathogenic ★★ same condition
CTC1 p.Ala227Val Pathogenic ★★ ⚠ same condition

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/ctc1-p-ala6 (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown