Genetic mutations of the TBX19 causing isolated CAI are rare but a number of genes encoding transcription factors involved in hypothalamic-pituitary gland development, as well as other genes including POMC and PC1, are associated with ACTH deficiency.
Among 22 independent patients from the GENHYPOPIT network who had ACTH deficiency and no identified mutation of TPIT, three of them (13.6%) displayed common variable immunodeficiency (CVID), characterized by defective Ig production.