According to a study in the American Journal of Human Genetics, a common brain deformation may partially be due to the cranial size of children.
Approximately one in 100 infants has Chiari 1 malformation, but most often the child grows up naturally and no one sees an issue. But some youngsters, around 10% of them, have problems including headaches, neck pain, ears, vision, and balance abnormalities.
Any individuals may have the disease hereditary, but scientists don't recognize the genetic variations that trigger it. Researchers also learned how Chiari 1 malformation can arise by researching how genes in the brain play a part in the creation of the skull. Study shows infants with disproportionately wide heads are four times more likely to be born with Chiari 1 malformation.
“A lot of times people have recurrent headaches, but they don’t realize a Chiari malformation is the cause of their headaches,” said senior author Gabriel Haller, PhD, an assistant professor of neurosurgery, of neurology and of genetics. “And even if they do, not everyone is willing to have brain surgery to fix it. We need better treatments, and the first step to better treatments is a better understanding of the underlying causes.” (Source: Washington University School of Medicine in St. Louis)
Haller and colleagues have sequenced the genes of 668 persons, along with 232 of their families, in order to classify genes that induce Chiari 1 malformation. Of the relatives, 76 had Chiari 1 malformation and 156 were unchanged.
People with Chiari 1 malformation have a slightly greater risk of carrying mutations in the Chromodomain family of genes. Several of the mutations arose in the patient during fetal growth and are not present in the patients families. The chromodomain genes CHD3 and CHD8 have various variants linked with malformation.
Experimental studies in zebrafish found the gene CHD8 is active in managing brain size. The animals grew extraordinarily big heads, with little improvement in their overall body size, when the researchers inactivated one copy of the fish's CHD8 gene.
Haller and colleagues were motivated by the correlation between chromodomain genes and head size to assess the heads of children with Chiari malformations, contrasting them with age-matched controls and with community averages given by the Centers for Disease Control and Prevention. Kids with Chiari appeared to have heads that were wider than normal. Those infants with the biggest head were four times more likely to be born with the malformation, greater than 95 percent of children of the same generation.
“A lot of kids that have autism or developmental disorders associated with chromodomain genes may have undiscovered Chiari malformations,” Haller said. “The only treatment right now is surgery. Discovering the condition early would allow us to watch, knowing the potential for serious symptoms is there, and perform that surgery as soon as it’s necessary.”