HealthDay News — For children with a first-degree relative with chronic tic disorder (CTD), Group-A streptococcal (GAS) exposure is not associated with tic onset, according to a study published online February 2 in Neurology.

Anette Eleonore Schrag, MD, PhD, from University College London, and colleagues examined the association between GAS infections and tic incidence in children aged 3 to 10 years with no history of tics, who had a first-degree relative with CTD. A total of 260 children were recruited, and one was excluded after being found to have tic onset before study entry.

The researchers found that over an average follow-up period of 1 year, 61 children (23.6%) developed tics. There was a strong association observed sex and tic onset, with about a 60% lower risk of developing tics for girls vs boys (hazard ratio, 0.4). There was no evidence to suggest an association for any of the 4 GAS exposure definitions (based on throat swabs, serum anti-streptolysin O titers and Anti-DNAse B titers) with tic onset.

“Results from this study may suggest that GAS exposure at least in those with genetic risk factors do not play an important role in the occurrence of tics,” the authors write. “The lack of association between GAS exposure and tic onset suggests that future research needs to examine the relationships between tic onset and a wider range of factors, including other pathogens.”

Several authors disclosed financial ties to the biopharmaceutical industry.

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