Russian and foreign biologists conducted a kind of "protein census" among autistic and healthy people and found serious differences in how the brain of both produces various enzymes and signaling molecules. Their findings were presented in the journal Communications Biology.
According to the WHO, one in 59 children worldwide have autism spectrum disorders, and the number of children with autism is increasing by 13% every year. In recent years, scientists have discovered dozens of genes associated with autism, but mutations in them cannot fully explain a single case of the development of this disease in general and its individual symptoms in particular.
For example, three years ago, American scientists noticed, experimenting on mice, that autism is associated not only with the presence of certain mutations in the genes that control the work and development of the brain, but also with bacteria in the intestines of autists and their parents. The transplantation of healthy microflora, as subsequent experiments showed, alleviated many of the symptoms of autism.
According to the Skoltech press service, Khrameeva and her colleagues approached the study of this problem from the other side - they checked how much the protein content of the brain cells of autists, healthy people, as well as two species of primates close to us, chimpanzees and macaques, differs greatly.
By comparing the concentrations of various proteins in their nerve tissue, the scientists hoped to understand which genes are disrupted during the development of autism and the consequences of their excess or deficiency. In total, biologists have traced the differences in the proportions of almost one and a half thousand proteins involved in the work of 16 most important metabolic chains in the neurons of the brain.
To do this, scientists collected tissue samples of the prefrontal cortex and other parts of the brain from about three dozen deceased autistic people, as well as four dozen of their peers who did not suffer from such disorders. When biologists extracted proteins from them, they revealed their composition and measured the proportions using chromatographs and mass spectrographs.
As it turned out, such disorders were indeed present in autistic cells and they were quite significant. Russian researchers and their foreign colleagues found evidence that the concentrations of two hundred proteins, about 15% of their total, differed significantly between autists and other people.
Many of these have been linked to the cycling of various amino acids and other short organic molecules such as nicotinamide and purine. Nerve cells use them not only to assemble important molecules within themselves, but also as chemical signals to "communicate" with neighbors and auxiliary brain bodies.
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Interestingly, these failures in the work of proteins and associated genes were so pronounced that they could easily distinguish autists from other people, as well as assess the severity of their symptoms.
In addition, Russian researchers have found hints that autism is unique to humans. The genes and proteins whose work is disrupted in carriers of this syndrome turned out to be most altered during the evolution of the genus Homo after its separation from the ancestors of chimpanzees and macaques.
All this information, scientists hope, will help us understand how to prevent the development of autism and help current and future carriers of this syndrome.