Finally, we evaluated the proximal limb cluster 6 and found a clear anti-correlation between Hoxd13 and Hoxa11. Of note, the expression of Shox2 was not decreased in inv2 cells from cluster 6, showing that the mesomelic phenotype was not induced by a secondary effect through this proximal limb gene, which in human is the causative agent of other types of limb reductions associated with short-stature syndromes48–50. The gene discussed is SHOX2; the disease is short stature due to GHSR deficiency.