Nitisinone inhibits the conversion of 4-OH phenylpyruvate to homogentisic acid by 4-Hydroxyphenylpyruvate dioxygenase, the second step in tyrosine degradation. By inhibiting this enzyme, the accumulation of the fumarylacetoacetate is prevented. Previously, liver transplantation was the primary treatment option and is still used in patients in whom nitisinone fails.Clinical treatment of HT1 relies on medications and strict regulation of diet. Nitisinone and dietary restrictions that decrease the amount of tyrosine and phenylalaine absorbed from the GI tract during protein digestion are used in combination as therapeutic measures that control the disease state if they are continued indefinitely. If not, there is a lack of control over the disease, resulting in continued liver and kidney damage, contributing to organ failure and death. In this case, a liver transplant may be required. Levels of SA are monitored throughout treatment in order to assess treatment effectiveness. Diet
The prescribed diet for treatment of HT1 is low in protein. Patients received amino acid supplements lacking tyrosine and phenylalanine in order to acquire sufficient protein. It is recommended that tyrosine levels remain below 500 μmol/L. Phenylalnine is the precursor to tyrosine. The ideology behind maintaining low tyrosine levels is two-fold. Firstly, it prevents the toxic metabolic intermediates from accumulating as a result of the dysfunctional tyrosine metabolic pathway. Prior to the introduction of nitisinone, this was the main treatment measure. Secondly, the mechanism of action of nitisinone is prevention of any tyrosine metabolism, thus it is important to prevent tyrosine from accumulating.
Types
Notable cases
Jyoti Amge - Indian actress, worlds shortest woman since her 18th birthday on 16 December 2011
Caroline Crachami – known as the "Sicilian Fairy", displayed in the Hunterian Museum in Scotland
Chandra Bahadur Dangi – smallest man of all time
Nelson de la Rosa – actor linked to the USA baseball team Boston Red Sox
Aditya Dev – worlds smallest bodybuilder
Bridgette Jordan and Brad Jordan – siblings
Khagendra Thapa Magar – worlds shortest man from his 18th birthday on 14 October 2010 to 13 June 2011
Gul Mohammed – former smallest man of all time
He Pingping – worlds shortest ambulatory man until his death in 2010
Weng Weng – Filipino actor and martial artist
Lucía Zárate – Mexican entertainer and first person identified to have MOPD II

See also
Gigantism
Dwarfism
Psychogenic dwarfism
List of people with dwarfism


== References ==