Association of the Neurotrophic Tyrosine Kinase Receptor 3 ( NTRK3 ) Gene and Childhood-Onset Mood Disorders

Objective: Genome scans have revealed significant evidence for linkage of depression to chromosome 15q25.3-q26.2. The gene for neurotrophic tyrosine kinase receptor 3 ( NTRK3 ), the receptor for neurotrophin-3 (trkC) and a key gene in neurotrophin signaling, is located within this region and, given evidence for synaptic plasticity as a mechanism in mood disorders, was considered a prime candidate. The authors investigated NTRK3 as a susceptibility gene for childhood-onset mood disorders. Method: The study sample consisted of 603 families with 723 affected children and adolescents diagnosed with a mood disorder with onset of the first episode by age 15. The authors genotyped 18 polymorphic markers across the NTRK3 gene in this sample and tested for association. Results: Results identified significant evidence for association for five of the markers using the transmission disequilibrium test. Four of the five markers were located in a region of strong linkage disequilibrium and were highly correlated. Haplotype results provided significant evidence for association to haplotypes composed of markers located in two haplotype blocks. Conclusions: The results for NTRK3 as well as the authors’ previous finding for association to brain-derived neurotrophic factor in this sample support synaptic plasticity as a mechanism contributing to mood disorders that begin during childhood and adolescence and specifically implicate the NTRK3 gene as a contributing factor in the 15q-linked region.