Inheritance and impact of parental sex on clinical expression of Tourette syndrome

Abstract

Background:
Tourette syndrome (TS) is a highly heritable neurodevelopmental disorder characterized by multiple motor and vocal tics. While genetic factors play a major role, the potential influence of the sex of the affected parent on symptom expression and development of symptoms remains unclear.
Objective:
This study aimed to examine whether maternal versus paternal disposition affects the clinical presentation and longitudinal course of TS in offspring.
Methods:
A total of 310 children and adolescents with TS were included from the Danish National Tourette Clinic cohort (baseline 2005-2007; follow-up 2011-2013). Participants were categorized according to parental TS disposition (maternal, paternal, or none). Tic severity was assessed at both time points using the Yale Global Tic Severity Scale (YGTSS). Group comparisons were performed for age at onset, age at diagnosis, tic severity, and symptom progression.
Results:
No significant or clinically meaningful differences were found in age at onset, age at diagnosis, or sex distribution between parental and sporadic cases, nor between maternal and paternal transmission. Patients with a parental disposition showed higher baseline tic severity but also slightly greater improvement in tic severity over time compared with sporadic cases. However, the magnitude of these differences was modest.
Conclusion:
This study provides the first longitudinal evidence that maternal and paternal inheritance might not have a differential effect on the early clinical presentation of TS. Familial TS may modestly influence long-term symptom trajectories, offering new insight into the heritable mechanisms underlying TS progression.