Ornithine transcarbamylase deficiency also known as OTC deficiency is the most common urea cycle disorder in humans. Ornithine transcarbamylase, the defective enzyme in this disorder is the final enzyme in the proximal portion of the urea cycle, responsible for converting carbamoyl phosphate and ornithine into citrulline. OTC deficiency is inherited in an X-linked recessive manner, meaning males are more commonly affected than females. In severely affected individuals, ammonia concentrations increase rapidly causing ataxia, lethargy and death without rapid intervention. OTC deficiency is diagnosed using a combination of clinical findings and biochemical testing, while confirmation is often done using molecular genetics techniques. Once an individual has been diagnosed, the treatment goal is to avoid precipitating episodes that can cause an increased ammonia concentration. The most common treatment combines a low protein diet with nitrogen scavenging agents. Liver transplant is considered curative for this disease. Experimental trials of gene therapy using adenoviral vectors resulted in the death of one participant, Jesse Gelsinger, and have been discontinued. Signs and symptoms
As with several other metabolic conditions, OTC deficiency can have variable presentations, regarding age of onset and the severity of symptoms. This compounded when considering heterozygous females and the possibility of non-random X-inactivation. In the classic and most well-known presentation, a male infant appears well initially, but by the second day of life they are irritable, lethargic and stop feeding. A metabolic encephalopathy develops, and this can progress to coma and death without treatment.
For unilocular GOCs with minimal tissue deterioration, "enucleation, curettage, and marsupialization" is a suitable treatment plan. Notably, the performance of enucleation or curettage as the primary action is linked to an incomplete extraction of the GOC and is only recommended to the less invasive lesions. Multilocular GOCs require a more invasive procedure such as "peripheral ostectomy, marginal resection, or partial jaw resection". GOCs associated with a more severe structural damage are encouraged to undergo marsupialization as either an initial or supplementary surgery. The frequency of reappearance is likely due to the lingering cystic tissue structures that remain after the performance of curettage. The incorporation of a "dredging method i.e. repetition of enucleation and curettage" is also suggested until the remnants of the GOC diminishes for certain. The treatment ensures scar tissue is removed to promote the successful reconstruction of osseous material for jaw preservation. Alongside the main treatments, bone allograft application, cryosurgery, and apicoectomy are available but have not been consistently recommended. Though Carnoys solution, the chloroform-free version, is recommended with the treatment as it degenerates the majority of the damaged dental lamina. The most effective type of treatment remains unknown due to the lack of detailed data from reported cases. Post-treatment protocols
Follow-up appointments are necessary after the removal of the GOC as there is a high chance of remission, which may be exacerbated in cases dealing with "cortical plate perforation". The GOC has a significant remission rate of 21 to 55% that can potentially develop during the period of 0.5 to 7 years post-surgery.