Limb-girdle muscular dystrophy type 2H
* LGMD2H has been observed only in the Hutterite people of Manitoba . * This disease is allelic with sarcotubular myopathy (see Congenital Myopathies). * Most patients have a mild phenotype, with limb-girdle weakness and a waddling gait at presentation. The proximal arm muscles and the distal leg muscles are involved late. * The age of onset is 8-27 years; some patients are asymptomatic in their third decade. * Back pain and fatigue are common symptoms. * Progression is slow, with continued ambulation until around 50 years of age or later.
* To date, all patients have been Hutterites from Manitoba with the same Asp487Asn homozygous point mutation; this is the same mutation as that found in sarcotubular myopathy. * TRIM32 protein is an E3-ubiquitin ligase that transfers activated ubiquitin residues onto a target protein, tagging the protein for degradation in the proteosome. * On muscle biopsy, no protein accumulations or inclusions have been identified.
Patients may have a late onset, slow progression, no cardiac symptoms, but mild ECG changes. This form is reported in the Hutterite population.
This depends upon the type. In general slow progression of weakness is to be expected. The affected muscles get worse and it spreads to more muscles. Morbidity and mortality varies between the various types but generally an early onset is associated with a more rapid decline and early mortality.6 In the slow types the patient may still be ambulatory 30 years later. The autosomal dominant forms tend to be less severe than the recessive.