Clinical Features and Laboratory Diagnosis of Aminoacidopathies: A Narrative Review

Context:

There are severe and rare groups of genetic disorders due to defects in metabolic pathways, and they are generally called inborn errors of metabolism. Amino acids, as the building blocks of proteins, have many important structural and functional roles in the human body. The deficiencies of functional enzymes cause defects in metabolic pathways and lead to aminoacidopathies. The diagnosis of aminoacidopathies is challenging for most physicians, as they can present with multiple overlapping symptoms.

Evidence Acquisition: 

PubMed, Cochrane, Embase, and CINAHL were searched with MeSH terms: ‘inborn errors of metabolism’ OR ‘Metabolism, Inborn Errors’ (MeSH) AND ‘Humans’ (MeSH) AND ’Amino Acids/therapeutic use’[MeSH] AND ‘Newborn, Child’ (MeSH) OR ‘child’ OR ‘newborn’ AND "Neonatal Screening"[MeSH].

This study summarized some important issues, including clinical and laboratory diagnoses of phenylketonuria, tyrosinemia, methionine, homocysteine and cysteine, sulfite oxidase deficiency, molybdenum cofactor deficiency, tryptophan, glycine, hyperoxaluria, creatine deficiency disorders, serine, proline, glutamine, and urea cycle defect.

The prognosis of many metabolic disorders has improved due to recent advances in diagnosis and treatment. The biochemical knowledge of clinicians should be improved to comprehend metabolic disorders. As the diagnostic methods are based on organic acids in urine and acylcarnitine profile, it is necessary to enhance biochemistry knowledge to understand the logic.