The urea cycle disorders (UCDs) comprise diseases presenting with hyperammonemia that arise in either the neonatal period or later. Congenital defects of the enzymes or transporters of the urea cycle cause the disease. This cycle utilizes five enzymes, carbamoylphosphate synthetase 1 and ornithine transcarbamylase are present in the mitochondrial matrix, whereas the others (argininosuccinate synthetase, argininosuccinate lyase and arginase 1) are present in the cytoplasm. In addition, N-acetylglutamate synthase and at least two transporter proteins are essential to urea cycle function. Severity and age of onset depend on residual enzyme or transporter function and are related to the respective gene mutations. UCDs symptoms correlate to the ammonia level in the body.

Inborn errors of primary bile acid synthesis are rare inherited autosomal recessive disorders. The most frequent defects are the 3β-Δ5-hydroxy-C27-steroid oxidoreductase (3β-HSD) deficiency which is due to mutations in HSD3B7; and to a lesser extent the Δ4–3-oxosteroid-5β-reductase (Δ4–3-oxo-R) deficiency due to mutations in AKR1D1. These defects in enzymes lead to an inadequate synthesis of primary BA that are critical for bile formation and to the production and the accumulation of atypical and hepatotoxic BA intermediates. These deficiencies are most commonly manifest in neonates or infants as cholestasis and can progress to early cirrhosis and liver failure unless treated.

Peyronie’s Disease (PD) is a superficial fibrosing disorder of the penis resulting in plaque formation and penile deformity. Once considered rare, PD has more recently been found in up to 13% of men, and can negatively affect sexual and psychosocial function of both patients and their partners. While the etiology of PD is unclear, it is thought to result from an inciting traumatic event followed by aberrant fibrosis or dysregulated wound healing. PD is often associated with erectile dysfunction (ED), as well as several other comorbidities. Treatment modalities for PD are diverse and include oral, topical, intralesional, and surgical therapies.

Cushing syndrome is a clinical syndrome caused by the chronic oversecreation of glucocorticoid by adrenal cortex due to multiple reasons. Direct symptons are shown clinically, among which moon-shaped face, central obesity, acne, purple striae, hypertension are the most typical ones. More than half of the patients with Cushing’s syndrome suffer from major depression, atypical depression and other types of mental and psychological disorder.

Erythropoietic protoporphyria (EPP) is caused by a mutation of ferrochelatase resulting in the accumulation of protoporphyrins in red blood cells that causes acute, painful, non-blistering photosensitivity and potential liver disease. It typically presents in early childhood with immediate pain and crying upon exposure to bright sunlight.

EPP is a lifelong disease, and repeated phototoxic reactions eventually lead to thickening of the skin and wax-like scarring on the face. In a small number of patients, the accumulation of protoporphyrins in the liver leads to cirrhosis and liver failure. Onset in adulthood is rare, but an acquired form has been identified, in which clones of cells with mutated ferrochelatase expand in the setting of the myelodysplastic or myeloproliferative syndrome.