SLC35D3 is expressed primarily in striatal neurons that project to the substantia nigra and the globus pallidus externa in the brain (Lobo et al., 2006), and mice with a recessive mutation in the SLC35D3 gene have decreased motor activity, impaired energy expenditure, and develop obesity (Zhang et al., 2014). This evidence concerns the gene SLC35D3 and obesity due to melanocortin 4 receptor deficiency.