SPG7 and myopathy: The formation of m-AAA metaloproteases with altered substrate specificities probably leads to leads to axonal degeneration in HSP.2 Pfefer G et al4 showed SPG7 mutations caused increased mitochondrial biogenesis in muscle, with the clonal expansion of mitochondrial DNA mutations resulting in eye symptoms and myopathy.9 There are only few studies to show whether clinical features mitochondrial dysfunction secondary to SPG 7 mutation becomes more prominent with growing age and if any phenotype genotype correlation exists or not.