Limb Girdle Muscular Dystrophies LGMDs

Synonyms:

formerly pelvifemoral type, Laden-Mobius variant and scapulohumeral type

Diagnosis:

Autosomal: most are recessive. Must confirm with genetic testing especially for sarcoglycan and dysferlin.

Muscle biopsy:

Similar to Duchenne muscular dystrophy
Cytoplasmic changes may occur: split fibres, whorls, moth eaten fibres, lobulated fibres
Hints to subtypes:

  • GMT, Rimmed vacuoles= Telethoninopathy LGMD2G
  • GMT, Rod-like structures= myotilinopathy
  • NADH, lobulated fibres= Calpainopathy

Genetics:

Autosomal dominant types:

LGMD 1A, Myotilin, TTID gene chr. 5q31
LGMD 1B, Lamin A/C
LGMD 1C, Caveolin-3
LGMD 1D, chr. 7q
LGMD 1E
LGMD 1F, chr. 7q32

Autosomal recessive types:

LGMD 2A, Calpain-3
LGMD 2B, dysferlin. If distal it’s called Miyoshi myopathy a.k.a. distal myopathy
LGMD 2C, gamma-Sarcoglycan
LGMD 2D, alfa-Sarcoglycan
LGMD 2E, beta-Sarcoglycan
LGMD 2F, delta-Sarcoglycan
LGMD 2G, Telethonin, TCAP gene chr. 17q12
LGMD 2H, TRIM32
LGMD 2I, Fukutin-related protein
LGMD 2J, Titin
LGMD 2K, protein o-mannosyltransferase-1 POMT1 gene chr. 9q34.1

Clinical features:

Onset 10-30 years
Pelvic or shoulder girdle weakness and wasting, gradually progressive.
Preserved facial muscles and ocular muscles
Preserved ankle jerks, depressed other jerks
Calve pseudohypertrophy may occur as well as quadriceps pseudohypertrophy

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