SLC16A2 and Global developmental delay: We postulate that the homogeneous inactivation of MCT8 in male individuals and female individuals with almost complete skewing (eg, due to balanced X-autosomal translocations generally leading to inactivation of the “normal” X-chromosome (29), such as in P4 and P5) may lead to severe global developmental delay, concealing the effect of MCT8 inactivation on more complex brain functions such as behavior and emotion regulation.