Urea cycle disorders (UCDs) are genetic conditions resulting from deficiencies in one of the enzymes involved in the urea cycle.
These disorders lead to the accumulation of ammonia and other toxic substances in the blood, causing serious health issues.
Here’s a brief overview of the main disorders:
1) Carbamoyl Phosphate Synthetase I Deficiency (CPS I Deficiency)
Inheritance: Autosomal recessive
Symptoms: Hyperammonemia, lethargy, vomiting, seizures, and developmental delay.
Management: Low-protein diet, medications to remove ammonia, and liver transplantation in severe cases.
2) Ornithine Transcarbamylase Deficiency (OTC Deficiency)
Inheritance: X-linked recessive
Symptoms: Hyperammonemia, vomiting, lethargy, seizures, and cognitive impairment.
Management: Similar to CPS I deficiency; includes ammonia scavengers and dietary management.
3) Argininosuccinate Synthetase Deficiency (Citrullinemia Type I)
Inheritance: Autosomal recessive
Symptoms: Hyperammonemia, lethargy, poor feeding, vomiting, and developmental delay.
Management: Protein restriction, arginine supplementation, and ammonia-lowering medications.
4) Argininosuccinate Lyase Deficiency (Argininosuccinic Aciduria)
Inheritance: Autosomal recessive
Symptoms: Hyperammonemia, hepatomegaly, developmental delay, and brittle hair.
Management: Low-protein diet, arginine supplementation, and ammonia scavengers.
5) Arginase Deficiency (Argininemia)
Inheritance: Autosomal recessive
Symptoms: Hyperammonemia, spasticity, growth delay, and seizures.
Management: Protein restriction and medications to lower ammonia levels.
Clinical Implications
Early Diagnosis: Newborn screening and genetic testing are essential for early diagnosis and treatment.
Dietary Management: Protein-restricted diets and supplementation with specific amino acids can help manage symptoms.
Medications: Ammonia scavengers and other medications can help reduce ammonia levels.
Liver Transplant: In severe cases, liver transplantation may be necessary.