DRD2 and obesity due to melanocortin 4 receptor deficiency: Genetic distribution of selected obesity-related SNVs in the &lt;i&gt;FTO&lt;/i&gt;, &lt;i&gt;DRD2&lt;/i&gt;, &lt;i&gt;MC4R&lt;/i&gt;, &lt;i&gt;FABP2&lt;/i&gt;, &lt;i&gt;ADRB2&lt;/i&gt;, and &lt;i&gt;SH2B1&lt;/i&gt; genes in a Mexico city population.