Defects can involve seizures, movement disorders , headaches , and cognitive (thought) disorders such as developmental delay or dementia (forgetfulness, senility). People with mitochondrial myopathies can also have hearing loss

In either the mitochondria or chloroplast depending on the organism. Two common mitochondrial disorder in human include: Mitochondrial Myopathy and Leber's hereditary optic. Mitochondrial disorders are always inherited maternally, meaning only the mother passes on the disorders because the energy in the mitochondria of the sperm is used up when it enters the female egg.

It exists because the DNA in mitochondria is duplicated without the checkpoints that nuclear DNA duplication has. Mitochondrial DNA disorders may occur spontaneously and relatively often.

Diseases such as Diabetes mellitus and deafness (DAD), Leber's hereditary optic neuropathy (LHON), Leigh syndrome, and Myoneurogenic gastrointestinal encephalopathy (MNGIE) can be considered to be mitochondrial disorders.

the mitochondrial mutations effect to those cells which have maternal inherritance character and the mutation is called poky mutation