A novel link between Tourette's syndrome and histaminergic signalling.

Tourette’s syndrome (TS) is a heritable neuropsychiatric disorder that is characterized by the display of repetitive tics. These tics are defined as sudden and recurring stereotyped vocalizations or movements. The incidence of TS includes a large environmental component as considerable phenotypic variability between monozygotic twin TS cases has been observed (1). Although TS is not associated with lower life expectancy or intelligence, the condition can nonetheless be socially debilitating. Fortunately, most cases of TS are rather mild, and hence many cases probably remain undiagnosed. Recently, significant progress has been made in identifying genetic components of TS, including the discovery of copy number variations (2) and genes (3) associated with the disease. Some of these genetic changes are associated with other neuropsychiatric disorders including schizophrenia, autism, and attention-deficit hyperactivity disorder (2). Thus, the picture of the genetic factors that contribute exclusively to TS remains somewhat blurred. Because the molecular pathways underlying TS have yet to yield many direct therapeutic targets, the current treatments are non-specific to TS and are limited to alleviating the symptomatic tics. Moreover, many TS treatments are undesirable due to their highly invasive nature. Therapies for TS consist of neurosurgery, deep brain stimulation, behavioural modification, and medication (4). The drugs used to treat TS include anti-psychotics, stimulants, anti-hypertensives, and anti-depressants; many of these evoke strong side effects (4). Therefore, there is a clear need to discover and characterize novel pathways associated with TS to develop alternative treatment strategies. In the current study, Ercan-Sencicek et al. aimed to identify mutations associated with a familial form of TS. In the affected family, all eight