SLITRK1 (Slit and Trk-like family member 1) is a integral membrane protein belonging to the SLITRK family consists of at least 6 members (SLITRK1-6). They are named and characterized by the presence of two leucine-rich repeats (LRRs) in the extracellular domain similar to those found in a secreted axonal growth-controlling protein, Slit, as well as a C-terminal domain with homology to Trk neurotrophin tyrosine kinase receptors. Expression of SLITRKs are highly restricted to neural tissues, and are identified as the neuronal components modulating the neurite outgrowth. More specifically, SLITRK1 expression is found in the mature neurons of the cerebrum, thalamus and hippocampus, and induces unipolar neurites in cultured neuronal cells. Human SLITRK1 is a 696 amino acid precursor protein, and one truncating frameshift mutation (448 aa) has been linked to Tourette's syndrome, a genetically influenced developmental neuropsychiatric disorder characterized by chronic vocal and motor tics. In addition, all SLITRK genes are differentially expressed in brain tumors, such as astrocytoma, oligodendroglioma, glioblastoma, and are suggested to be useful molecular indicators of brain tumor properties.