Hyperargininemia: A Rare Diagnosis in Adulthood.

Area of Science:

• Biochemistry
• Genetics
• Neurology

Background:

• Hyperargininemia is a rare, autosomal recessive urea cycle disorder caused by arginase I deficiency.
• It typically leads to progressive neurological damage and is usually diagnosed before age 4.
• Neonatal screening via mass spectrometry has been available in Portugal since 2007.

Purpose of the Study:

• To present a case of late-diagnosed hyperargininemia in a 23-year-old woman.
• To emphasize the importance of recognizing clinical features for early diagnosis.
• To highlight the internist's role in diagnosing rare diseases.

Main Methods:

• Clinical case presentation.
• Neurological examination.
• Genetic analysis revealing a homozygous pathological variant in the ARG1 gene.
• Biochemical analysis showing elevated blood arginine levels.

Main Results:

• A 23-year-old woman with a history of rhabdomyolysis, learning difficulties, and falls was diagnosed with hyperargininemia.
• Genetic testing confirmed a homozygous ARG1 variant.
• Elevated arginine levels supported the diagnosis.

Conclusions:

• Hyperargininemia is the rarest urea cycle disorder, often diagnosed in early childhood.
• Delayed diagnosis can occur, underscoring the need for clinical vigilance.
• Early intervention is key to mitigating neurological progression.