MedGen

Progressive damage to mitochondrial DNA (mtDNA) during life is thought to contribute to aging processes. This notion is supported by the observation of an aging-related accumulation in human mtDNA of oxidative and alkylation derivatives of nucleotides, of small deletions and insertions, and of large deletions, although their low frequency raises questions about their functional significance (Michikawa et al., 1999). [from OMIM]

A progressive chronic inflammatory disease of the central nervous system with the aetiologic agent Human T cell lymphotropic virus type I (HTLV-I), the disease is characterised by unremitting myelopathic symptoms such as spastic paraparesis, bowel and/or bladder dysfunction and sensory changes of the lower limbs. [from SNOMEDCT_US]

Normal color vision in humans is trichromatic, being based on 3 classes of cone that are maximally sensitive to light at approximately 420 nm (blue cones; 613522), 530 nm (green cones; 300821), and 560 nm (red cones; 300822). Comparison by neural circuits of light absorption by the 3 classes of cone photoreceptors allows perception of red, yellow, green, and blue colors individually or in various combinations. Dichromatic color vision is severely defective color vision based on the use of only 2 types of photoreceptors, blue plus green (protanopia) or blue plus red (deuteranopia; see 303800). Anomalous trichromacy is trichromatic color vision based on a blue, green, and an anomalous red-like photoreceptor (protanomaly), or a blue, red, and an anomalous green-like photoreceptor (deuteranomaly). The color vision defect is generally mild but may in certain cases be severe. Common variation in red-green color vision exists among both normal and color-deficient individuals (review by Deeb, 2005). [from OMIM]

A type of anomalous trichromacy associated with defective long-wavelength-sensitive (L) cones, causing the sensitivity spectrum to be shifted toward medium wavelengths. This leads to difficulties especially in distinguishing red and green. [from HPO]

Developmental and epileptic encephalopathy-91 (DEE91) is characterized by delayed psychomotor development apparent in infancy and resulting in severely to profoundly impaired intellectual development with poor or absent speech. Most patients never achieve independent walking. Patients typically have onset of refractory multifocal seizures between the first weeks and years of life, and some may show developmental regression. Additional features, such as hypotonia and cortical visual impairment, are more variable (summary by Myers et al., 2017). For a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]