- Short stature (HP:0004322): A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms). Evidence: IEA. (OMIM:530000)
- 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:530000)
- Pigmentary retinopathy (HP:0000580): An abnormality of the retina characterized by pigment deposition. It is typically associated with migration and proliferation of macrophages or retinal pigment epithelial cells into the retina; melanin from these cells causes the pigmentary changes. Pigmentary retinopathy is a common final pathway of many retinal conditions and is often associated with visual loss. Evidence: IEA. (OMIM:530000)
- 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:530000)
- Arrhythmia (HP:0011675): Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both. Evidence: IEA. (OMIM:530000)
- Diabetes mellitus (HP:0000819): A group of abnormalities characterized by hyperglycemia and glucose intolerance. Evidence: IEA. (OMIM:530000)
- Third degree atrioventricular block (HP:0001709): Third-degree atrioventricular (AV) block (also referred to as complete heart block) is the complete dissociation of the atria and the ventricles. Third-degree AV block exists when more P waves than QRS complexes exist and no relationship (no conduction) exists between them. Evidence: IEA. (OMIM:530000)
- Renal tubular acidosis (HP:0001947): Acidosis owing to malfunction of the kidney tubules with accumulation of metabolic acids and hyperchloremia, potentially leading to complications including hypokalemia, hypercalcinuria, nephrolithiasis and nephrocalcinosis. Evidence: IEA. (OMIM:530000)
- 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:530000)
- Sideroblastic anemia (HP:0001924): Sideroblastic anemia results from a defect in the incorporation of iron into the heme molecule. A sideroblast is an erythroblast that has stainable deposits of iron in cytoplasm (this can be demonstrated by Prussian blue staining). Evidence: IEA. (OMIM:530000)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: IEA. (OMIM:530000)
- Lactic acidosis (HP:0003128): An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids. Evidence: IEA. (OMIM:530000)
- Basal ganglia calcification (HP:0002135): The presence of calcium deposition affecting one or more structures of the basal ganglia. Evidence: IEA. (OMIM:530000)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: IEA. (OMIM:530000)
- Ragged-red muscle fibers (HP:0003200): An abnormal appearance of muscle fibers observed on muscle biopsy. Ragged red fibers can be visualized with Gomori trichrome staining as irregular and intensely red subsarcolemmal zones, whereas the normal myofibrils are green. The margins of affect fibers appear red and ragged. The ragged-red is due to the accumulation of abnormal mitochondria below the plasma membrane of the muscle fiber, leading to the appearance of a red rim and speckled sarcoplasm. Evidence: IEA. (OMIM:530000)
- Progressive external ophthalmoplegia (HP:0000590): Initial bilateral ptosis followed by limitation of eye movements in all directions and slowing of saccades. Evidence: IEA. (OMIM:530000)
- Hypoparathyroidism (HP:0000829): A condition caused by a deficiency of parathyroid hormone characterized by hypocalcemia and hyperphosphatemia. Evidence: IEA. (OMIM:530000)
- Sensorineural hearing impairment (HP:0000407): A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve. Evidence: IEA. (OMIM:530000)
- 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:530000)
- Ptosis (HP:0000508): The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective). Evidence: IEA. (OMIM:530000)
- Cardiomyopathy (HP:0001638): A myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valvular disease and congenital heart disease sufficient to cause the observed myocardial abnormality. Evidence: IEA. (OMIM:530000)
- Increased CSF protein concentration (HP:0002922): Increased concentration of protein in the cerebrospinal fluid. Evidence: TAS. (OMIM:530000)
- Sensory neuropathy (HP:0000763): Peripheral neuropathy affecting the sensory nerves. Evidence: IEA. (OMIM:530000)
- Renal Fanconi syndrome (HP:0001994): An inability of the tubules in the kidney to reabsorb small molecules, causing increased urinary loss of electrolytes (sodium, potassium, bicarbonate), minerals, glucose, amino acids, and water. Evidence: TAS. (OMIM:530000)
- Primary adrenal insufficiency (HP:0008207): Insufficient production of steroid hormones (primarily cortisol) by the adrenal glands as a result of a primary defect in the glands themselves. Evidence: IEA. (OMIM:530000)
These phenotypes are associated with the disease Kearns-Sayre syndrome (OMIM:530000).