IEMbase 0644: FKTN-related muscular dystrophy-dystroglycanopathy type C

Scope

Field	Value
IEMbase ID	644
Nosology	18.2.08.03
Gene	FKTN
External IDs	OMIM:611588; ORPHA:272
Generated mapping	UNMAPPED; weak candidate Dystroglycanopathy.yaml
Candidate DisMech targets	Dystroglycanopathy.yaml; possible future LGMD subtype context
Review date	2026-07-07

IEMbase phenotype signal

IEMbase represents this as autosomal recessive FKTN-CDG type C, the limb-girdle muscular dystrophy end of the FKTN dystroglycanopathy spectrum.

Biochemical rows include markedly increased plasma creatine kinase across ages and normal serum sialotransferrins. Clinical rows emphasize limb-girdle muscular dystrophy, optional hypotonia, optional cardiomyopathy, and optional rigid spine from childhood onward.

DisMech phenotype coverage

Dystroglycanopathy.yaml captures the FKTN gene subtype (MDDG4) and the type C severity subtype. It represents defective alpha-dystroglycan glycosylation, elevated CK, muscular dystrophy, proximal weakness, and the continuous severity gradient from severe congenital disease to limb-girdle disease.

Autosomal_Recessive_Limb-Girdle_Muscular_Dystrophy.yaml has a specific FKRP LGMDR9 subtype but does not appear to include an FKTN limb-girdle subtype. Therefore, the best current local target remains Dystroglycanopathy.yaml rather than the AR LGMD file.

Concordance and completeness

Judgement: broad local coverage; missing exact FKTN limb-girdle row.

DisMech covers the mechanism and the type C category, but the exact FKTN type C / limb-girdle entity is not rooted as its own local subtype. IEMbase-specific prompts that would improve future curation include rigid spine and explicit cardiomyopathy in the FKTN limb-girdle context.

Curation actions

• Map broadly to Dystroglycanopathy.yaml.
• Do not map to AR LGMD unless an FKTN-specific recessive LGMD subtype is added there.
• Preserve CK, normal sialotransferrins, limb-girdle muscular dystrophy, hypotonia, cardiomyopathy, and rigid-spine prompts.