Key Takeaway
The siblings had different cardiac phenotypes and imaging courses. A two-person family report cannot set surveillance intervals or change public cardiac guidance without specialist review.
Evidence Summary
Discordant Cardiomyopathy Phenotypes in Siblings With Homozygous FKRP c.1100T>C
Two-sibling case report describing different cardiac courses despite the same homozygous FKRP variant.
case reportCardiacPhenotypeClinicians
Citation: Mahon N, Coad S, Kiamanesh O. Discordant Cardiomyopathy Phenotypes in Siblings With Homozygous FKRP c.1100T>C. JACC Case Rep. 2026;31(26):108364.
Main findings
- The report describes two adult siblings with the same homozygous FKRP variant and different extent and progression of cardiac involvement.
- Serial cardiac magnetic resonance imaging showed persistent or changing fibrosis patterns that were not fully represented by ejection fraction alone.
- Follow-up duration and disease stage differed between the two siblings.
Practical relevance
- Illustrates intrafamilial variability and supports research questions about cardiac imaging and genotype modifiers.
- Does not establish how often the pattern occurs or which imaging schedule improves outcomes.
Limitations and cautions
- Two people from one family cannot support population estimates, genotype-wide predictions, or a universal surveillance protocol.
- Follow-up was shorter for one sibling, fibrosis was assessed semiquantitatively, and a broad cardiomyopathy gene panel was not performed.
- The authors’ surveillance proposals are expert interpretation from a case report and have not been adopted here as guidance.
Primary Sources
Direct links for verification
Primary indexed record for the paper summary on this page.
Publisher DOI landing page.
Full text used to check the two-person case history, imaging follow-up, limitations, and disclosures.
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Study Record
A Study of Deflazacort (Emflaza®) in Participants With Limb-Girdle Muscular Dystrophy 2I (LGMD2I)
Phase 3 corticosteroid study record evaluating deflazacort in adults with FKRP-related LGMD2I, ultimately terminated early.
Guide
Clinical Features
FKRP-related disease can involve skeletal muscle, motor development, cardiac function, respiratory function, and in some severe congenital presentations, broader neurologic or structural findings. The pattern is variable, which is why the site treats phenotype as a spectrum.