Here, we describe the identification of anaplastic lymphoma kinase (ALK) as a candidate gene for AUDs based on evidence from flies, mice, and humans. ALK is a receptor tyrosine kinase in the insulin receptor family that was first identified as an oncogenic chromosomal translocation in anaplastic large cell lymphoma [6]. More recently, translocations and mutations in ALK have been associated with lung cancer [7] and neuroblastoma [8], [9], [10], [11], suggesting a key function for ALK in the development of several cancers. With regard to the nervous system, Drosophila Alk (dAlk) is important for axon targeting in the retina and synapse development at the neuromuscular junction [12], [13]. In mice, Alk is expressed in the developing and adult nervous system [14], [15] and inhibits hippocampal progenitor cell proliferation as well as depression-associated behaviors [16]. One human study has shown an association of polymorphisms in ALK with schizophrenia in a Japanese population [17], suggesting that ALK potentially affects the development of psychiatric disorders.
