| Disease ID | Source | Name | Description |
| 310440 | OMIM | Myopathy, X-linked, with excessive autophagy (MEAX) | A muscle disorder characterized by childhood early onset of a slowly progressive proximal limb muscle weakness (especially in legs) and elevation of serum creatine kinase, without evidence of cardiac, respiratory or central nervous system involvement. Histopathological analysis reveals diseased muscle fibers that are not necrotic, but show abnormal autophagic vacuolation as a manifestation of excessive autophagic activity in skeletal muscle cells. The disease is caused by variants affecting the gene represented in this entry. VMA21 deficiency results in an increase of lysosomal pH from 4.7 to 5.2, which reduces lysosomal degradative ability and blocks autophagy. This reduces cellular free amino acids, which upregulates the mTOR pathway and mTOR-dependent macroautophagy, resulting in proliferation of large and ineffective autolysosomes that engulf sections of cytoplasm, merge together, and vacuolate the cell. |