Adrenocorticotropic hormone (ACTH) hypersecretion by corticotroph adenomas of the pituitary result in excess cortisol secretion, or Cushing disease. The clinical features of Cushing disease include central obesity, moon facies, 'buffalo hump,' diabetes, hypertension, fatigue, easy bruising, depression, and reproductive disorders. Cushing disease is associated with increased morbidity and mortality, mainly due to cardiovascular or cerebrovascular disease and infections (summary by Perez-Rivas et al., 2015). Mutations in the USP8 gene, leading to an upregulated epidermal growth factor receptor (EGFR; 131550) pathway, have been identified in about 36 to 62% of corticotroph adenomas (summary by Mete and Lopes, 2017).

Congenital secretory chloride diarrhea is an autosomal recessive form of severe chronic diarrhea characterized by excretion of large amounts of watery stool containing high levels of chloride, resulting in dehydration, hypokalemia, and metabolic alkalosis. The electrolyte disorder resembles the renal disorder Bartter syndrome (see 607364), except that chloride diarrhea is not associated with calcium level abnormalities (summary by Choi et al., 2009). Genetic Heterogeneity of Diarrhea Other forms of diarrhea include DIAR2 (251850), caused by mutation in the MYO5B gene (606540) on 18q21; DIAR3 (270420), caused by mutation in the SPINT2 gene (605124) on 19q13; DIAR4 (610370), caused by mutation in the NEUROG3 gene (604882) on 10q21; DIAR5 (613217), caused by mutation in the EPCAM gene (185535) on 2p21; DIAR6 (614616), caused by mutation in the GUCY2C gene (601330) on 12p12; DIAR7 (615863) caused by mutation in the DGAT1 gene (604900) on 8q24; DIAR8 (616868), caused by mutation in the SLC9A3 gene (182307) on 5p15; DIAR9 (618168), caused by mutation in the WNT2B gene (601968) on 1p13; DIAR10 (618183), caused by mutation in the PLVAP gene (607647) on 19p13; DIAR11 (618662), caused by deletion of the intestine critical region (ICR) on chromosome 16p13, resulting in loss of expression of the flanking gene PERCC1 (618656); DIAR12 (619445), caused by mutation in the STX3 gene (600876) on 11q12; and DIAR13 (620357), caused by mutation in the ACSL5 gene (605677) on chromosome 10q25.

N-acetylglutamate synthase deficiency (NAGSD) is an autosomal recessive disorder of the urea cycle. The clinical and biochemical features of the disorder are indistinguishable from carbamoyl phosphate synthase I deficiency (237300), since the CPS1 enzyme (608307) has an absolute requirement for NAGS (Caldovic et al., 2007).