Table 1.

Current “pre-next generation sequencing” genetic diagnostic yield of individuals with suspected mitochondrial disease

Definite primary mitochondrial disease
mtDNA cytopathy	13.2 %
Nuclear gene disorder	3.2 %
Probable/possible mitochondrial disease
mtDNA variant of unconfirmed pathologic significance	5.3 %
Abnormal tissue biochemistry and no clear molecular etiology	2 %*
Normal tissue biochemistry and no clear molecular etiology	23 %*
Unlikely primary mitochondrial disease	44.1 %*
Proven other genetic disorder	9.2 %

*Individuals in whom next generation sequencing-based analysis of large nuclear gene panels, the whole exome, or even the whole genome are likely to have the greatest effect in improving the diagnostic yield in the clinical evaluation of suspected mitochondrial disease