NTRK2 and obesity due to melanocortin 4 receptor deficiency: The neurotrophic tyrosine kinase receptor type 2 (NTRK2) gene was screened in a boy with early onset obesity, hyperphagia developmental delay, impairments in short-term memory and impaired nociception, revealing a missense mutation in NTRK2 (Yeo et al., 2004).