acids in blood) The dried blood spot can be used for multianalyte testing using Tandem Mass Spectrometry (MS/MS). This given an indication for a disorder. The same has to be further confirmed by enzyme assays, IEX-Ninhydrin, GC/MS or DNA Testing. Quantitative measurement of amino acids in plasma and urine IEX-Ninhydrin post-column derivitization liquid ion chromatography (detects abnormal amino acid patterns and quantitative analysis) Urine organic acid analysis by gas chromatography–mass spectrometry Plasma acylcarnitine analysis by mass spectrometry Urine purine and pyrimidine analysis by gas chromatography-mass spectrometry Specific diagnostic tests (or focused screening for a small set of disorders): Tissue biopsy: liver, muscle, brain, bone marrow Skin biopsy and fibroblast cultivation for specific enzyme testing Specific DNA testing A 2015 review reported that even with all these diagnostic tests, there are cases when "biochemical testing, gene sequencing, and enzymatic testing can neither confirm nor rule out an IEM, resulting in the need to rely on the patient's clinical course". A 2021 review showed that several neurometabolic disorders converge on common neurochemical mechanisms that interfere with biological mechanisms also considered central in ADHD pathophysiology and treatment. This highlights the importance of close collaboration between health services to avoid clinical overshadowing. Treatment In the middle of the 20th century the principal treatment for some of the amino acid disorders was restriction of dietary protein and all other care was simply management of complications. In the past twenty years, new medications, enzyme replacement, gene therapy, and organ transplantation have become available and beneficial for many previously untreatable disorders. Some of the more common or promising therapies are listed: Epidemiology In a study in British Columbia, the overall incidence of the inborn errors of metabolism were estimated to be 40 per 100,000 live births or 1 in 2,500 births, overall representing more than approximately 15% of single gene disorders in the population. While a Mexican study established an overall incidence of 3.4: 1000 live newborns and a carrier detection of 6.8:1000 NBS. References Further reading External links Portal of Chemistry (Italian) Medical genetics Metabolism