It encompasses many genes involved in neuronal function (CEP43, NOX3, PDE10A, RNASET2, SERAC1, TULP4) and genetic disorders [ARID1B, Coffin-Siris syndrome 1 (www.orpha.net; ORPHA:1465) or microdeletion syndrome 6q25.2-q25.3; (ORPHA:251056) (Nagamani et al., 2009); SERAC1 deficiency and MEGDEL syndrome (ORPHA:352328); recessive mutations of GTF2H5 and trichothiodystrophy (ORPHA:33364); RSPH3 involved in primary ciliary dyskinesia (ORPHA:244); and PDE10A linked to infantile movement disorders (ORPHA:494541 and ORPHA:494526)]. The gene discussed is PDE10A; the disease is hyperinsulinemic hypoglycemia, familial, 4.