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Mitochondrial encephalomyelopathy, lactic acidosis, and stroke-like episodes (MELAS)
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
There is a considerable variety of expression consistent with the varying heteroplasmy of mitochondrial inheritance. The typical picture is of normal development followed by a severe, progressive encephalomyopathy. Onset may be myopathic with exercise intolerance or weakness (Figure 51.3). Many patients have shortness of stature and this may be the first manifestation of disease (Figure 51.4). One of our patients had been treated unsuccessfully with human growth hormone by a pediatric endocrinologist; this has also been reported by others. In many patients, the onset of symptoms is with the first stroke-like episode, usually between four and 15 years, certainly before 40 years and often triggered by infection or physical exercise. [1, 4, 8–14]. Less commonly, the onset of disease may be in infancy [8], often with delayed developmental milestones or learning disability.
Basic science, investigations and lasers
Published in Mostafa Khalil, Omar Kouli, The Duke Elder Exam of Ophthalmology, 2019
Tarek Khalil, Bilal Ibrahim, Stewart Gillan, Obaid Kousha
Chromosomes have a short arm, denoted as ‘p’, and a long arm, denoted as ‘q’. Human cells contain 46 chromosomes: 22 identical pairs and a pair of sex chromosomes. Genetic information can be carried on any of these chromosomes, and hence inheritance can be autosomal or sex-linked (X-linked). Other forms of inheritance that are covered here include mitochondrial inheritance, which is passed only by the mother.
Ophthalmology
Published in Ashley Bond, MRCP Part 2 Examination, 2017
Important associations: AbetalipoproteinaemiaKearns-Sayre syndrome – mitochondrial inheritance, see first-degree heart blockRefsum’s diseaseUsher’s syndromeAlport’s syndrome.
Outer retinal tubulations in maternally inherited diabetes & deafness – associated macular dystrophy: case report
Published in Ophthalmic Genetics, 2020
Maria Syriga, Vasileios Soumplis, Charalampos Kapernopoulos, Dimitris Kleftogiannis, Michael Karampelas
Due to the known mitochondrial inheritance pattern of the syndrome, the patient’s sister was subjected to thorough ophthalmologic and audiological examination as well. Her BCVA for both eyes was 8/10 according to Snellen chart, while no significant pathology was noted as far as the anterior segments are concerned. Pupil dilation followed by fundoscopic examination revealed mild non-proliferative diabetic retinopathy bilaterally and mild RPE changes in the posterior pole (Figure 4). OCT did not show any significant pathology in either eye (Figure 5). Audiological examination revealed a moderate sensorineural hearing loss with threshold at 45 dB for the left and 40–50 dB for the right ear (Figure 6). Based on the clinical findings she was advised for a standard annual ophthalmologic and audiological follow-up.
The applications of big data in molecular diagnostics
Published in Expert Review of Molecular Diagnostics, 2019
Yin Kwan Evelyn Wong, Ka Wai Lam, Ka Yi Ho, Chi Shing Allen Yu, Chi Shing William Cho, Hin Fung Tsang, Man Kee Maggie Chu, Po Wah Lawrence Ng, Chi Shing William Tai, Lawrence Wing Chi Chan, Elaine Yue Ling Wong, Sze Chuen Cesar Wong
Mendelian inheritance patterns among humans contribute vast numbers of genetic phenotypes and disorders while most of their disease mechanisms are poorly understood. To date, there are over 7,000 Mendelian diseases being identified, with the spectrum spanning through autosomal, X-linked, Y-linked to mitochondrial inheritance [17,24,25]. According to the Online Mendelian Inheritance of Men (OMIM), an online public database which serves to search for relationships between phenotype and genotype of all known Mendelian disorders, there are over 24,600 entries including descriptions of over 16,000 genes and 8,600 phenotypes [26].
The Natural History of Leber’s Hereditary Optic Neuropathy in an Irish Population and Assessment for Prognostic Biomarkers
Published in Neuro-Ophthalmology, 2022
Kirk A. J. Stephenson, Joseph McAndrew, Paul F. Kenna, Lorraine Cassidy
Leber’s hereditary optic neuropathy (LHON, OMIM#535000) is an inherited optic neuropathy (typically mitochondrial, rarely autosomal recessive) with a prevalence of 1:30,000–50,000.1–4 Males are affected in 80–90% of cases (3.4:1 with females, overall male prevalence 1:14,000).1,2 This is unexplained by mitochondrial inheritance, and likely modified by hormonal factors, mitochondrial deoxyribonucleic acid (mtDNA) haplotype or nuclear DNA modifiers.1,5–8 Lifetime LHON risk in mtDNA mutation carriers is 50% and 10% for males and females, respectively.9