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Ornithine transcarbamylase deficiency





Population genetics
Genetic disorders
Down syndrome (Trisomy 21)
Edwards syndrome (Trisomy 18)
Patau syndrome (Trisomy 13)
Fragile X syndrome
Huntington disease
Myotonic dystrophy
Friedreich ataxia
Turner syndrome
Klinefelter syndrome
Prader-Willi syndrome
Angelman syndrome
Beckwith-Wiedemann syndrome
Cri du chat syndrome
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Alagille syndrome (NORD)
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Tuberous sclerosis
von Hippel-Lindau disease
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Gaucher disease (NORD)
Glycogen storage disease type I
Glycogen storage disease type II (NORD)
Glycogen storage disease type III
Glycogen storage disease type IV
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Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)
Krabbe disease
Niemann-Pick disease types A and B (NORD)
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Primary ciliary dyskinesia
Phenylketonuria (NORD)
Sickle cell disease (NORD)
Tay-Sachs disease (NORD)
Wilson disease
Fragile X syndrome
Alport syndrome
X-linked agammaglobulinemia
Fabry disease (NORD)
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)
Lesch-Nyhan syndrome
Muscular dystrophy
Ornithine transcarbamylase deficiency
Wiskott-Aldrich syndrome
Mitochondrial myopathy
Autosomal trisomies: Pathology review
Muscular dystrophies and mitochondrial myopathies: Pathology review
Miscellaneous genetic disorders: Pathology review

Ornithine transcarbamylase deficiency


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High Yield Notes
7 pages

Ornithine transcarbamylase deficiency

9 flashcards

USMLE® Step 1 style questions USMLE

1 questions

A 2-week-old male infant comes to the emergency department because of unusual irritability and lethargy. Patient is admitted to the pediatric intensive care unit and minutes later develops metabolic encephalopathy. This progressed to a coma, followed by death, before any laboratory tests are completed. Infant was born at home via vaginal delivery at 39 weeks’ of gestation. His mother says that the symptoms  started since the infant was 4-days-old, but since he only seemed “tired,” she decided not to seek for medical attention. Further testing during autopsy shows hyperammonemia, low citrulline and increased orotic acid. Which of the following enzymes is most likely deficient in this patient?

External References
Ornithine transcarbamylase deficiency is the most common urea cycle disorder in humans. It is inherited in an X-linked manner. The defective enzyme, ornithine transcarbamylase, is the final enzyme in the proximal portion of the urea cycle, responsible for converting carbamoyl phosphate and ornithine into citrullaine. In severe cases, rapidly increasing ammonia concentrations cause ataxia, lethargy and death without rapid intervention. This deficiency is diagnosed through clinical findings and biochemical testing, confirmed with molecular genetics techniques. Treatment aims to avoid precipitating increased ammonia levels. The most common treatment combines a low protein diet with nitrogen scavenging agents. Liver transplant is considered curative for this disease.