OBJECTIVE To analyze the clinical and genetic characteristics of a patient with congenital isolated adrenocorticotropic hormone deficiency (IAD). METHODS Clinical characteristics of the patient was reviewed. Genomic DNA of the child was subjected to whole exome sequencing. RESULTS Genetic testing has confirmed the diagnosis of congenital IAD by identification of compound heterozygous variants of the TBX19 gene, which included a pathogenic nonsense c.535C>T (p.R179X) variant inherited from his father and a novel missense c.298C>T (p.R100C) variant inherited from his mother. CONCLUSIONS Congenital IAD due to variants of the TBX19 gene is a rare autosomal recessive disease. It is characterized by low plasma adrenocorticotropic hormone and cortisol levels but normal levels of other pituitary hormones. Delayed diagnosis may lead to severe early-onset adrenal failure and wrong treatment which may result in neonatal mortality. Hydrocortisone replacement is effective. Detection of pathogenic variant of TBX19 gene is the key to diagnosis.