May 05, 2017 06:56 AM EDT By Emily Marks, UniversityHerald Reporter

Tourette disorder or Tourette syndrome can afflict as many as one person in a hundred globally. It is a disorder that comes with potentially disabling symptoms, which include involuntary motor and vocal tics.

Despite its wide reach, it is still unclear what causes the disorder. Treatments have also had limited success due in part to the fact that the genetics underlying it has continued to be a puzzle.

Now, research led by the University of California - San Francisco has identified the first "high-confidence" risk gene for Tourette disorder. Three other probable risk genes have also been recognized.

The study was conducted in collaboration with Rutgers University, Massachusetts General Hospital, the University of Florida and Yale School of Medicine. The authors noted that the findings are a step toward understanding the biology of Tourette disorder which can help with the development of better treatments.

The study was published in the journal "Neuron." The researchers compared the genomes of the children with Tourette disorder, particularly its protein-coding regions, to the genomes of their parents to identify "de novo" variants.

De novo variants are rare genetic mutations that are not inherited from parents. Instead, they occur spontaneously during conception. These also have more extreme effects than inherited mutations and can provide information about the underlying causes of a disease.

The team examined genomic data from 311 "trios," children with Tourette and their parents. They found strong evidence that these variants can play a major role in triggering the disorder.

The gene WWC1, also called KIBRA (for "KIdney- and BRAin-expressed protein), has a greater than 90 percent probability of contributing to Tourette disorder. It is involved in brain development, memory and the brain's response to the hormone estrogen.

The other three genes: FN1, CELSR3 and NIPBL or Delangin, have at least 70 percent probability of contributing to the disorder. The first two have been known to be involved in the development of brain circuitry while the third is involved in the regulation of gene expression in the brain.

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