Cystic Fibrosis, Modifier of, 1, also known as meconium ileus in cystic fibrosis, susceptibility to, is related to craniofacial microsomia 1 and cystic fibrosis. An important gene associated with Cystic Fibrosis, Modifier of, 1 is CFM1 (Cystic Fibrosis Modifier 1). Related phenotype is meconium ileus.