Speech difficulties included dysarthria (all HMD genes), language delay (infantile‐onset DDC‐, ATP1A3‐, FOXG1‐, GNAO1‐, PDE10A‐, SLC6A3‐, and TH‐related HMDs), bradylalia (neurotransmitters defects), and dysphonia (KMT2B). This evidence concerns the gene ATP1A3 and Delayed speech and language development.