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Disorders of vitamin B6 metabolism
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
Accumulated piperideine-6-carboxylate reacts with pyridoxal-5-phosphate in a Knoevenagel condensation (Figure 100.3a). This is an irreversible reaction which depletes PLP and results in seizures treatable by oral pyridoxine which resolves the seizure disorder. Hyperprolinemia (type II) due to defective activity of Δ1 pyrroline-5-carboxylate dehydrogenase leads to the accumulation of P5C which also reacts with PLP by a Knoevenagel condensation and is characterized by seizures. This provided the clue [19] to the pathogenesis of pyridoxine-dependent seizures and the defective mutation in antiquitin.
A pilot study on machine learning approach to delineate metabolic signatures in intellectual disability
Published in International Journal of Developmental Disabilities, 2021
Vidya Nikam, Suvidya Ranade, Naushad Shaik Mohammad, Mohan Kulkarni
In the present study, the technique of tandem mass spectrometry was successfully used to screen the children with the ID for IEM. No classical IEM was detected in 20 individuals screened. However, the comparison of each analyte in ID individuals with controls revealed that proline, phenylalanine, ornithine, and alanine were elevated in the ID group while arginine levels were found to be decreased. Although we have not observed any classical case of hyperprolinemia (OMIM 239500; 239510) presenting with seizures along with ID (Evers et al.2015), proline levels were higher in ID individuals. There are reports on the association of ID and hyperalaninemia associated with Leigh’s syndrome (OMIM 256000) (Tada et al.1973). Hyperornithinemia–hyperammonemia–homocitrullinuria (HHH) syndrome (OMIM 238970) is one of the commonest disorders associated with ornithine elevation resulting in growth and developmental delays, learning disabilities, periodic confusion, and ataxia (Martinelli et al.2015). High levels of phenylalanine in ID persons substantiate that there could be hydroxylation defects due to tetrahydrobiopterin resulting in low tyrosine levels.
Aldehyde toxicity and metabolism: the role of aldehyde dehydrogenases in detoxification, drug resistance and carcinogenesis
Published in Drug Metabolism Reviews, 2019
Amaj Ahmed Laskar, Hina Younus
Aldehydes are reactive organic molecules found ubiquitously in the environment. Several aldehydes are also produced within the body through metabolic processes. Majority of the aldehydes are toxic to the body causing aldehyde-mediated pathogenesis including cancer. The human body contains several aldehyde metabolizing enzyme systems among which ALDHs are one of the most important classes of enzymes responsible for the detoxification of aldehydes in the body. Human ALDHs perform several important functions within the body. Deficiency of different ALDHs activity leads to distinct pathological conditions including Sjögren-Larsson syndrome, paranoid schizophrenia, Type II hyperprolinemia, cataract, alcohol sensitivity and cancer. Involvement of hALDHs in diverse physiological and pathophysiological functions makes the enzyme diagnostically and therapeutically important. Although several studies have been undertaken on hALDHs, further investigations regarding their regulation, role in diseases including cancer, diabetes etc. and modulation of catalytic activity under in vitro and in vivo conditions seems to be important for establishing more in relation to disease manifestation, diagnosis and therapy.