- Retinal pigment epithelial mottling (HP:0007814): Mottling (spots or blotches of different shades) of the retinal pigment epithelium, i.e., localized or generalized fundus pigment granularity associated with processes at the level of the retinal pigment epithelium. Evidence: IEA. (OMIM:551500)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: IEA. (OMIM:551500)
- Myopathy (HP:0003198): A disorder of muscle unrelated to impairment of innervation or neuromuscular junction. Evidence: IEA. (OMIM:551500)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: IEA. (OMIM:551500)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: IEA. (OMIM:551500)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: IEA. (OMIM:551500)
- Dementia (HP:0000726): A loss of global cognitive ability of sufficient amount to interfere with normal social or occupational function. Dementia represents a loss of previously present cognitive abilities, generally in adults, and can affect memory, thinking, language, judgment, and behavior. Evidence: IEA. (OMIM:551500)
- Blindness (HP:0000618): Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation. Evidence: IEA. (OMIM:551500)
- Mitochondrial inheritance (HP:0001427): A mode of inheritance that is observed for traits related to a gene encoded on the mitochondrial genome. Because the mitochondrial genome is essentially always maternally inherited, a mitochondrial condition can only be transmitted by females, although the condition can affect both sexes. The proportion of mutant mitochondria can vary (heteroplasmy). Evidence: IEA. (OMIM:551500)
- Mitochondrial myopathy (HP:0003737): A type of myopathy associated with mitochondrial disease and characterized by findings on biopsy such as ragged red muscle fibers. Evidence: IEA. (OMIM:551500)
- Rod-cone dystrophy (HP:0000510): An inherited retinal disease subtype in which the rod photoreceptors appear to be more severely affected than the cone photoreceptors. Typical presentation is with nyctalopia (due to rod dysfunction) followed by loss of mid-peripheral field of vision, which gradually extends and leaves many patients with a small central island of vision due to the preservation of macular cones. Evidence: IEA. (OMIM:551500)
- Sensory neuropathy (HP:0000763): Peripheral neuropathy affecting the sensory nerves. Evidence: TAS. (OMIM:551500)
- Proximal muscle weakness (HP:0003701): A lack of strength of the proximal muscles. Evidence: IEA. (OMIM:551500)
- Retinopathy (HP:0000488): Any noninflammatory disease of the retina. This nonspecific term is retained here because of its wide use in the literature, but if possible new annotations should indicate the precise type of retinal abnormality. Evidence: IEA. (OMIM:551500)
- Corticospinal tract atrophy (HP:0007117). Evidence: IEA. (OMIM:551500)
These phenotypes are associated with the disease NARP syndrome (OMIM:551500).