Calpainopathy (a.k.a. LGMDR1) is the most common type of autosomal recessive limb-girdle muscular dystrophy (LGMD) It affects the muscles of the hip girdle and shoulder girdle.
Symptoms usually appear between the ages of 8 and 15. In severe cases, patients lose the ability to walk 10 - 20 years after symptoms first show.
It is linked to a mutation in the gene CAPN3, but the pathophysiology - the mechanism which leads to the disease - is unknown. To date, there is no effective treatment for this disease.
A 2019 research paper in the International Journal of Molecular Sciences suggests that it may be related to faulty calcium regulation - “Ca2+ dysregulation seems to play a central pathogenic role in this disease.”