Is TTN p.Pro259= (c.777G>A) pathogenic?

TTN p.Pro259= (c.777G>A) is classified Likely benign in TTN (ClinVar, Single submitter, 1 submitter; last evaluated 2025-04-14). Very rare (popmax 0.00267%, afr); Associated with dilated cardiomyopathy 1G.

What condition is associated with TTN p.Pro259= (c.777G>A)?

TTN p.Pro259= (c.777G>A) is associated with dilated cardiomyopathy 1G, autosomal recessive limb-girdle muscular dystrophy type 2J (ClinVar).

How common is TTN p.Pro259= (c.777G>A) in the general population?

TTN p.Pro259= (c.777G>A) is very rare (popmax 0.00267%, afr) (gnomAD).

How is Familial isolated dilated cardiomyopathy inherited?

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

TTN p.Pro259=

c.777G>A · rs779271206 · VCV2922805

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00267%, afr)

Conditions

dilated cardiomyopathy 1G

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 -4.9	GERP -4.4
Overall
CADD	1.697	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00267% African / African-American · 2/74,874 alleles

Filtering AF 0.000443% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000166%

Overall 0.00031% 5/1,613,944 alleles · very rare exomes 4/1,461,856 · genomes 1/152,088 · joint denominator

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.00267%	37,437
South Asian	0.0011%	91,084
European (non-Finnish)	0.000169%	590,005

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: TTN
Protein: p.Pro259=
Coding: c.777G>A
MANE Select: NM_001267550
dbSNP: rs779271206
Type: single nucleotide variant
Location: chr2:178799624 (GRCh38)
Gene constraint: LOEUF 0.479 · pLI <0.01 · ClinGen HI 2/3 (gnomAD)
Residue 259: the 'disordered' region; the 'zis1' region

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

Disease context

dilated cardiomyopathy 1G — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: autosomal recessive limb-girdle muscular dystrophy type 2J

For Familial isolated dilated cardiomyopathy (Orphanet):

Inheritance: Autosomal dominant, Autosomal recessive, Mitochondrial inheritance
Onset: All ages
Prevalence: 1-9 / 100 000 (Europe)

Similar variants

TTN c.100171+1G>A Likely pathogenic ★★ same condition
TTN c.100766-1G>T Likely pathogenic ★★ same condition
TTN c.100766-2A>T Likely pathogenic ★★ same condition
TTN c.106375-2A>G Pathogenic/Likely pathogenic ★★ same condition
TTN c.106531+1G>A Pathogenic/Likely pathogenic ★★ same condition
TTN c.107224-1G>C Pathogenic/Likely pathogenic ★★ same condition
TTN c.107377+1G>A Pathogenic/Likely pathogenic ★★ same condition
TTN c.107377+1G>C Pathogenic/Likely 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/ttn-p-pro259 (accessed [today's date]).

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