Is FLNC p.Phe42Cys (c.125T>G) pathogenic?

FLNC p.Phe42Cys (c.125T>G) is classified Uncertain significance in FLNC (ClinVar, Multiple submitters, 4 submitters; last evaluated 2025-11-03). AlphaMissense: likely pathogenic (0.9989); Very rare (popmax 0.000424%, nfe); Associated with myofibrillar myopathy 5.

What condition is associated with FLNC p.Phe42Cys (c.125T>G)?

FLNC p.Phe42Cys (c.125T>G) is associated with myofibrillar myopathy 5, distal myopathy with posterior leg and anterior hand involvement, hypertrophic cardiomyopathy 26 (ClinVar).

How common is FLNC p.Phe42Cys (c.125T>G) in the general population?

FLNC p.Phe42Cys (c.125T>G) is very rare (popmax 0.000424%, nfe) (gnomAD).

How is Muscle filaminopathy inherited?

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

What do computational predictors say about FLNC p.Phe42Cys (c.125T>G)?

AlphaMissense predicts likely pathogenic (score 0.9989) — an in-silico prediction, not a clinical call.

FLNC p.Phe42Cys

c.125T>G · rs777706683 · VCV642140

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 4 submitters

AlphaMissense

likely pathogenic

0.9989 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.000424%, nfe)

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

myofibrillar myopathy 5

Computational evidence

Protein change
AlphaMissense	0.9989	likely pathogenic · top 1% in FLNC
REVEL	0.888	moderately pathogenic-leaning
SaProt	LLR -15.48	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.8	phastCons 1
Regional constraint	o/e 0.34	constrained · MANE · 84 bp · p 5.6e-05 · regional, not allelic
Overall
CADD	31.0	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean damaging — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000424% European (non-Finnish) · 5/1,179,950 alleles

Filtering AF 0.000124% ClinGen BA1/BS1 input FAF95, joint · FAF99 9e-05%

Overall 0.00031% 5/1,613,182 alleles · very rare exomes 5/1,460,890 · genomes 0/152,292 · joint denominator

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: FLNC
Protein: p.Phe42Cys
Coding: c.125T>G
MANE Select: NM_001458
dbSNP: rs777706683
Type: single nucleotide variant
Location: chr7:128830762 (GRCh38)
Gene constraint: LOEUF 0.424 · pLI 1.00 · ClinGen HI 3/3 (gnomAD)
Residue 42: the calponin-homology (ch) 1 domain; the 'actin-binding' region

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

Disease context

myofibrillar myopathy 5 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: distal myopathy with posterior leg and anterior hand involvement hypertrophic cardiomyopathy 26

For Muscle filaminopathy (Orphanet):

Inheritance: Autosomal dominant
Onset: Adult

Similar variants

FLNC p.Phe42Ser Uncertain significance ★★ ⚠ same residue
FLNC p.Phe42= Likely benign ★★ same residue
FLNC p.Phe42fs Pathogenic ★ same residue
FLNC c.1047+1G>T Likely pathogenic ★★ same condition
FLNC c.1048-1G>A Likely pathogenic ★★ same condition
FLNC c.1210+1G>A Likely pathogenic ★★ same condition
FLNC c.1549+2T>G Likely pathogenic ★★ same condition
FLNC c.2007+1G>A 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/flnc-p-phe42cys (accessed [today's date]).

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