Scientists claim zinc deficiency could cause autism in babies after finding 'a mechanical link'
Scientists claim that autism could be caused by zinc deficiency in a new study published in the 'Frontiers in Molecular Neuroscience' journal
There have been numerous studies linking autism in children to not only genetic defects but also other variables. Even though scientists don't have a definitive answer of the causes of autism but, in a new study, US and German scientists say they have data to prove that zinc levels may be one of the factors causing this change, reported Daily Mail.
Scientists claim that autism could be caused due to a combination of "environmental factors" and genetic defects. Even though more research is needed to confirm the link between the level of zinc to autism, the researchers say they have found a mechanical link. They found that zinc forms the connections or 'synapses' between brain cells from an early developmental stage. These connections are formed through a complex molecular machinery encoded by autism risk genes, stated the report.
However, they warned pregnant women that the research is at an early stage and does not mean they should start taking Zinc supplements.
"Autism is associated with specific variants of genes involved in the formation, maturation, and stabilization of synapses during early development," said senior author Dr Sally Kim of Stanford University School of Medicine in California. Kim added, "Our findings link zinc levels in neurons — via interactions with the proteins encoded by these genes — to the development of autism."
Co-author Professor Craig Garner of the German Centre for Neurodegenerative Diseases also said that there are no controlled studies of autism risk with zinc supplementation among pregnant women or babies. Garner added, "We really can't make any conclusions or recommendations for zinc supplementation at this point, but experimental work in autism models also published in this Frontiers Research Topic holds promise. Nevertheless, our findings offer a novel mechanism for understanding how zinc deficiency - or disrupted handling of zinc in neurons - might contribute to autism."
Zinc is important for a growing body as it helps in creating new cells and enzymes, processing carbohydrate, fat and protein in food, along with healing of the wounds. The National Health Services (NHS) said that most people get their zinc requirements from their diet and should not take more than 25mg of zinc supplements per day unless adviced by their doctors. As the increased quantity of zinc could reduce the body's ability to absorb copper, which can lead to anemia and weakening of the bones, reported the publication.
This study published in 'Frontiers in Molecular Neuroscience' journal found that, when a signal is transferred via a synapse, zinc enters the target neuron and can connect two such proteins, Shank2 and Shank3. These proteins cause changes in the function and composition of nearby signal receptors called 'AMPARs' on the surface of the neuron at a synapse.
The experiments carried out showed the mechanism of zinc-Shank-mediated AMPAR maturation in forming synapses.
"In developing rat neurons, we found that Shank 2 and 3 accumulate at synapses in parallel with a switch to mature AMPARs. Adding extra zinc accelerated the switch — but not when we reduced the accumulation of Shank 2 or 3. Furthermore, our study shows mechanistically how Shank2 and 3 work in concert with zinc to regulate AMPAR maturation, a key developmental step," stated Lead author Researcher Dr. Huong Ha at Stanford.
Zinc shapes the properties of forming synapses through shank proteins informed co-senior author Professor John Huguenard of Stanford. Prof Huguenard added in conclusion, "This suggests that a lack of zinc during early development might contribute to autism through impaired synaptic maturation and neuronal circuit formation. Understanding the interaction between zinc and Shank proteins could, therefore, lead to diagnostic, treatment and prevention strategies for autism."