This failure of ornithine transport causes an interruption of the urea cycle and the accumulation of ammonia, resulting in the signs and symptoms of ornithine translocase deficiency.This disorder is inherited in an autosomal recessive pattern, which means the defective gene is located on an autosome, and two copies of the gene - one from each parent - are required to be born with the disorder. The parents of an individual with an autosomal recessive disorder each carry one copy of the altered gene but do not show signs and symptoms of the disorder. Diagnosis
Clinical findings in HHH syndrome are non-specific. If the disorder is suspected, laboratory testing can provide diagnostic information. Plasma amino acid analysis will show elevated ornithine levels, and urine amino acids will detect homocitrulline. Orotic acid may also be elevated. Ammonia levels can be variably elevated. If these findings are present, molecular testing may provide additional confirmatory information. Treatment
Treatments include discontinuation of protein intake, intravenous infusion of glucose and, as needed, infusion of supplemental arginine and the ammonia removal drugs, sodium phenylacetate and sodium benzoate. See also
Ornithine transcarbamylase deficiency
Inborn errors of metabolism
Ornithine aminotransferase deficiency (gyrate atrophy of the choroid and retina)

References
Charles Scriver, Beaudet, A.L., Valle, D., Sly, W.S., Vogelstein, B., Childs, B., Kinzler, K.W. (accessed 2007). New York: McGraw-Hill. Summaries of 255 chapters, full text through many universities. There is also the OMMBID blog. Further reading
Ornithine translocase deficiency at NLM Genetics Home Reference


== External links ==
Tiopronin, sold under the brand name Thiola, is a medication used to control the rate of cystine precipitation and excretion in the disease cystinuria. Due to the rarity of the disorder, tiopronin falls under the classification of an orphan drug. It is somewhat similar to penicillamine in both chemistry and pharmacology.A generic version of tiopronin is available in the United States as of April 2021. Uses
Tiopronin is used primarily for cystinuria and is well known in the cystinuric community. Depending on the severity of a persons cystinuria, tiopronin may be taken for life, possibly starting in early childhood. The drug works by reacting with urinary cysteine to form a more soluble, disulfide linked, tiopronin-cysteine complex. Side effects
Tiopronin may present a variety of side effects, which are broadly similar to those of D-penicillamine and other compounds containing active sulfhydryl groups. Its pharmacokinetics have been studied. Society and culture
In the U.S., the drug was marketed by Mission Pharmacal at $1.50 per pill, but in 2014 the rights were bought by Retrophin, owned by Martin Shkreli, and the price increased to $30 per pill for a 100 mg capsule.In 2016 Imprimis Pharmaceuticals introduced a lower cost version marketed as a compounded drug. Research
It may also be used for Wilsons disease (an overload of copper in the body), and has also been investigated for the treatment of arthritis, though tiopronin is not an anti-inflammatory.Tiopronin is also sometimes used as a stabilizing agent for metal nanoparticles. The thiol group binds to the nanoparticles, preventing coagulation. References
External links
"Tiopronin". Drug Information Portal.