SIPA1L2, a Rap GTPase-activating protein, regulates the process of neurotransmitter liberation, which is linked to TrkB/Rap1 signaling and amphisomes that are the fusion organelles of TrkB-late endosomes with autophagosomes [58], while others, including TBC1D5 and TBC1D15, are associated with motor neuron disease, and these GAPs cause the disorder-degradable process of autophagy and the aggregation of toxic proteins [59–63]. The gene discussed is NTRK2; the disease is motor neuron disorder.