Some symptoms of mitochondrial diseases are subtle while others are lifelong and easily noticeable. Mitochondrial disease can appear either in adults or children; Typically, childhood mitochondrial disease is more astringent “and includes progressive neurological, cardiac, and hepatic dysfunction.” A wide range of symptoms may be apparent in childhood mitochondrial disease, "including lethargy, hypotonia, failure to thrive, seizures, cardiomyopathy, deafness, blindness, movement disorders, and lactic acidosis." . In contrast, most patients with mitochondrial disease do not have very noticeable symptoms. Most recognizable symptoms can usually be attributed to other causes; However, further analysis could lead to mitochondrial mutations being the definitive cause, especially these symptoms in the following systems. Mitochondrial diseases of the central nervous system or peripheral nervous system typically present with stereotypical childhood symptoms, such as “developmental delay or regression, seizures, and movement disorders.” In adult-onset mitochondrial disease, symptoms are more likely to involve stroke or stroke-like episodes. Symptomatic or nonsymptomatic peripheral neuropathy may be revealed during a "physical examination or nerve conduction studies." Due to mitochondrial diseases of the auditory system, sensorineural hearing loss due to cochlear dysfunction and dysfunction of the mitochondria of the VIII cranial nerve can occur. Because eye muscles contain "the highest density of mitochondria per cell of any muscle type and therefore use large amounts of adenosine triphosphate, mitochondrial diseases in the eye system are rather abundant." Symptoms of these eye syndromes include a progressive outpatient ophthalmologist...... middle of article......G, Yolanda Lillquist, MD, FRCPC. "Clinical manifestations of mitochondrial disease: an overview". British Columbia Medical Journal 53.4 (2011): 183-87. British Columbia Medical Journal. Internet. April 18, 2014. Sirrs, Sandra, MD, FRCPC, Margaret O'Riley, RN, MA, Lorne Clark, MDCM, FRCPC,FCCMG, and Andre Mattman, MD, FRCPC. “Primer on mitochondrial diseases: biochemistry, genetics and epidemiology.” British Columbia Medical Journal 53.4 (2011): 172-76. British Columbia Medical Journal. Internet. April 18, 2014. “What is mitochondrial disease?” What is mitochondrial disease. United Mitochondrial Disease Foundation, nd Web. April 19. 2014. .