Is TTN p.Ser6978= (c.20934T>C) pathogenic?

TTN p.Ser6978= (c.20934T>C) is classified Likely benign in TTN (ClinVar, Single submitter, 1 submitter; last evaluated 2025-09-15). Very rare (popmax 0.00659%, sas); Associated with autosomal recessive limb-girdle muscular dystrophy type 2J.

How common is TTN p.Ser6978= (c.20934T>C) in the general population?

TTN p.Ser6978= (c.20934T>C) is very rare (popmax 0.00659%, sas) (gnomAD).

How is Titin-related limb-girdle muscular dystrophy R10 inherited?

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

TTN p.Ser6978=

Q: What condition is associated with TTN p.Ser6978= (c.20934T>C)?

TTN p.Ser6978= (c.20934T>C) is associated with autosomal recessive limb-girdle muscular dystrophy type 2J, dilated cardiomyopathy 1G (ClinVar).

c.20934T>C · VCV3761021

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00659%, sas)

Conditions

autosomal recessive limb-girdle muscular dystrophy type 2J

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 -7.8	GERP -5.8
Overall
CADD	0.121	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00659% South Asian · 6/91,066 alleles

Filtering AF 0.00286% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00195%

Overall 0.000744% 12/1,613,326 alleles · very rare

Ancestry group	Frequency	1 in
South Asiangrpmax	0.00659%	15,178
Admixed American	0.00167%	59,960
European (non-Finnish)	0.000424%	235,907

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.Ser6978=
Coding: c.20934T>C
MANE Select: NM_001267550
Type: single nucleotide variant
Location: chr2:178724441 (GRCh38)
Gene constraint: LOEUF 0.479 · pLI <0.01 · ClinGen HI 2/3 (gnomAD)
Residue 6978: the ig-like 51 domain

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

Disease context

autosomal recessive limb-girdle muscular dystrophy type 2J — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: dilated cardiomyopathy 1G

For Titin-related limb-girdle muscular dystrophy R10 (Orphanet):

Inheritance: Autosomal recessive
Onset: Adolescent, Adult, Childhood

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-ser6978 (accessed [today's date]).

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