Proof-of-principle has also been provided by studies using patient-derived iPSCs from a patient with SP-B deficiency; transduction with a lentiviral vector expressing SP-B and subsequent differentiation of the iPSCs into organoids resulted in functional mature lamellar bodies and secretion of SP-B into the supernatant128. This evidence concerns the gene SFTPB and hyperinsulinemic hypoglycemia, familial, 4.