Homozygous variants in the genes coding for MED11 (OMIM 620327), MED17 (OMIM 613668), MED20 (OMIM 612915) and MED27 (OMIM 619286), located in the head region of the complex, were associated with global developmental delay (GDD), microcephaly, spasticity, dystonia, epilepsy and variably cataracts, accompanied by cerebellar and in part pontine atrophy [2–6]. This evidence concerns the gene MED20 and microcephaly.