Autism spectrum disorder is classified as a pervasive neurodevelopmental disorder. It refers to a group of complex disorders with a very wide range of clinical features, which in 1-2% of children begin to be expressed in the early years of development. The most common and most pronounced characteristics are limited social communication, difficulties with verbal and nonverbal interactions as well as poor ability to develop interpersonal relationships. Due to the complexity of the disorder, a definitive clinical test to diagnose the disease has not been developed. Currently, a diagnostic algorithm that involves a combination of psychological and clinical assessments of specific traits is used. The main current etiological theory is based on a complex combination and interaction of genetic and epigenetic changes, where genetic, epigenetic and environmental factors are intertwined as risk factors and causes of disease development. Changes in the functioning of the immune system, mitochondria, methylation mechanisms, amino acid metabolism and oxidative stress have also been confirmed in association with the disease. Based on the findings of changes in certain biochemical pathways, studies have begun to identify appropriate biological markers that could be used to diagnose patients with autism spectrum disorder. Development is taking place in the direction of detecting specific genetic changes, as well as determining the concentrations of specific analytes involved in critical biochemical pathways.
Based on previous research, we decided to examine the possibility of using certain methylated nucleosides as biological markers of autism spectrum disorder. They have been proven to change their concentration in the presence of certain pathological processes in the body. Since they are said to represent the major physiological catabolic products of human purine and pyrimidine metabolism, six analytes have been selected, namely, O-methylguanosine, 3-methyladenine, 1-methylguanine, 1-methyladenosine, 7-methylguanine and 8-hydroxy-2'-deoxyguanosine. Analyte concentrations were determined from a urine sample by high performance liquid chromatography coupled by mass spectrometry. The results were compared with the control group and also according to the severity of the diagnosis and the presence of additional diagnoses of neurological origin. The analysis of the collected data confirmed that in patients with autism spectrum disorders there are some constant and characteristic deviations in analyte concentrations according to the control group. What is more, deviations from the control group increase with weight, as well as the presence of additional diagnoses. Based on the results, it would therefore make sense to continue the development of the diagnostic methods by introducing nucleoside biomarkers into the diagnostic algorithm of autism spectrum disorder.
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