Direct sequence analysis of genomic DNA from blood can be used to perform a mutation analysis for the TALDO1 gene responsible for the Transaldolase enzyme.

Autozygome analysis and biochemical evaluations of urinary sugars and polyols can be used to diagnose Transaldolase Deficiency. Two specific methods for measuring the urinary sugars and polyols are liquid chromatographytandem mass spectrometry and gas chromatography with flame ionization detection.

Current research suggests that nearly 8% of the population has at least partial DPD deficiency. A diagnostics determination test for DPD deficiency is available and it is expected that with a potential 500,000 people in North America using 5-FU this form of testing will increase. The whole genetic events affecting the DPYD gene and possibly impacting on its function are far from being elucidated, and epigenetic regulations could probably play a major role in DPD deficiency. It seems that the actual incidence of DPD deficiency remains to be understood because it could depend on the very technique used to detect it. Screening for genetic polymorphisms affecting the "DPYD" gene usually identify less than 5% of patients bearing critical mutations, whereas functional studies suggest that up to 20% of patients could actually show various levels of DPD deficiency.

Women could be more at risk than men. It is more common among African-Americans than it is among Caucasians.

A small number of genetic variants have been repeatedly associated with DPD deficiency, such as IVS14+1G>A mutation in intron 14 coupled with exon 14 deletion (a.k.a. DPYD*2A), 496A>G in exon 6; 2846A>T in exon 22 and T1679G (a.k.a. DPYD*13) in exon 13. However, testing patients for these allelic variants usually show high specificity (i.e., bearing the mutation means that severe toxicity will occur indeed)but very low sentivity (i.e., not bearing the mutation does not mean that there is no risk for severe toxicities). Alternatively, phenotyping DPD using ex-vivo enzymatic assay or surrogate testing (i.e., monitoring physiological dihydrouracil to uracil ratio in plasma) has been presented as a possible upfront strategy to detect DPD deficiency. 5-FU test dose (i.e., preliminary administration of a small dose of 5-FU with pharmacokinetics evaluation) has been proposed as another possible alternative strategy to secure the use of fluoropyrimidine drugs.

The diagnosis is based on clinical features, with a concomitant decreased blood adenosine deaminase level supporting the diagnosis.

Infant mortality is high for patients diagnosed with early onset; mortality can occur within less than 2 months, while children diagnosed with late-onset syndrome seem to have higher rates of survival. Patients suffering from a complete lesion of mut0 have not only the poorest outcome of those suffering from methylaonyl-CoA mutase deficiency, but also of all individuals suffering from any form of methylmalonic acidemia.

Treatment of THB deficiencies consists of THB supplementation (2–20 mg/kg per day) or diet to control blood phenylalanine concentration and replacement therapy with neurotransmitters precursors (L-DOPA and 5-HTP) and supplements of folinic acid in DHPR deficiency.

Tetrahydrobiopterin is available as a tablet for oral administration in the form of "tetrahydrobiopterin dihydrochloride" (BH4*2HCL). BH4*2HCL is FDA approved under the trade name Kuvan. The typical cost of treating a patient with Kuvan is $100,000 per year. BioMarin holds the patent for Kuvan until at least 2024, but Par Pharmaceutical has a right to produce a generic version by 2020. BH4*2HCL is indicated at least in tetrahydrobiopterin deficiency caused by GTPCH deficiency or PTPS deficiency.

As one of the urea cycle disorders, citrullinemia type I needs to be distinguished from the others: carbamyl phosphate synthetase deficiency, argininosuccinic acid lyase deficiency, ornithine transcarbamylase deficiency, arginase deficiency, and N-Acetylglutamate synthase deficiency. Other diseases that may appear similar to CTLN1 include the organic acidemias and citrullinemia type II. To diagnose CTLN1, a blood test for citrulline and ammonia levels can indicate the correct diagnosis; high levels of both are indicative of this disorder. Newborns are routinely screened for CTLN1 at birth. A genetic test is the only definitive way to diagnose it.

In most regions, galactosemia is diagnosed as a result of newborn screening, most commonly by determining the concentration of galactose in a dried blood spot. Some regions will perform a second-tier test of GALT enzyme activity on samples with elevated galactose, while others perform both GALT and galactose measurements. While awaiting confirmatory testing for classic galactosemia, the infant is typically fed a soy-based formula, as human and cow milk contains galactose as a component of lactose. Confirmatory testing would include measurement of enzyme activity in red blood cells, determination of Gal-1-P levels in the blood, and mutation testing. The differential diagnosis for elevated galactose concentrations in blood on a newborn screening result can include other disorders of galactose metabolism, including galactokinase deficiency and galactose epimerase deficiency. Enzyme assays are commonly done using fluorometric detection or older radioactively labeled substrates.

Diagnostic measures can include the following.

Before birth:

- Abnormally low levels of UDP-N-acetylglucoseamine-1-phosphodiesterase enzyme activity in amniotic fluid cells or chronic villi

In infants:

- Elevated plasma lysosomal enzyme concentration

- Decreased concentration of lysosomal enzymes in cultured fibroblasts

- Presence of inclusion bodies and peripheral blood lymphocytes

- Low levels of UDP-N-acetylglucoseamine-1-phosphotransferase enzyme activity as measured in white blood cells

This condition is very rare; approximately 600 cases have been reported worldwide. In most parts of the world, only 1% to 2% of all infants with high phenylalanine levels have this disorder. In Taiwan, about 30% of newborns with elevated levels of phenylalanine have a deficiency of THB.

Several tests can be done to discover the dysfunction of methylmalonyl-CoA mutase. Ammonia test, blood count, CT scan, MRI scan, electrolyte levels, genetic testing, methylmalonic acid blood test, and blood plasma amino acid tests all can be conducted to determine deficiency.

There is no treatment for complete lesion of the mut0 gene, though several treatments can help those with slight genetic dysfunction. Liver and kidney transplants, and a low-protein diet all help regulate the effects of the diseases.

The term homocystinuria describes an increased excretion of the thiol amino acid homocysteine in urine (and incidentally, also an increased concentration in plasma). The source of this increase may be one of many metabolic factors, only one of which is CBS deficiency. Others include the re-methylation defects (cobalamin defects, methionine sythase deficiency, MTHFR) and vitamin deficiencies (cobalamin (vitamin B12) deficiency, folate (vitamin B9) deficiency, riboflavin deficiency (vitamin B2), pyridoxal phosphate deficiency (vitamin B6)). In light of this information, a combined approach to laboratory diagnosis is required to reach a differential diagnosis.

CBS deficiency may be diagnosed by routine metabolic biochemistry. In the first instance, plasma or urine amino acid analysis will frequently show an elevation of methionine and the presence of homocysteine. Many neonatal screening programs include methionine as a metabolite. The disorder may be distinguished from the re-methylation defects (e.g., MTHFR, methionine synthase deficiency and the cobalamin defects) in lieu of the elevated methionine concentration. Additionally, organic acid analysis or quantitative determination of methylmalonic acid should help to exclude cobalamin (vitamin B12) defects and vitamin B12 deficiency giving a differential diagnosis.

The laboratory analysis of homocysteine itself is complicated because most homocysteine (possibly above 85%) is bound to other thiol amino acids and proteins in the form of disulphides (e.g., cysteine in cystine-homocysteine, homocysteine in homocysteine-homocysteine) via disulfide bonds. Since as an equilibrium process the proportion of free homocystene is variable a true value of total homocysteine (free + bound) is useful for confirming diagnosis and particularly for monitoring of treatment efficacy. To this end it is prudent to perform total homocyst(e)ine analysis in which all disulphide bonds are subject to reduction prior to analysis, traditionally by HPLC after derivatisation with a fluorescent agent, thus giving a true reflection of the quantity of homocysteine in a plasma sample.

Although there is currently no cure, treatment includes injections of structurally similar compound, N-Carbamoyl-L-glutamate, an analogue of N-Acetyl Glutamate. This analogue likewise activates CPS1. This treatment mitigates the intensity of the disorder.

If symptoms are detected early enough and the patient is injected with this compound, levels of severe mental retardation can be slightly lessened, but brain damage is irreversible.

Early symptoms include lethargy, vomiting, and deep coma.

Diagnosis of Fatty-acid metabolism disorder requires extensive lab testing.

Normally, in cases of hypoglycaemia, triglycerides and fatty acids are metabolised to provide glucose/energy. However, in this process, ketones are also produced and ketotic hypoglycaemia is expected. However, in cases where fatty acid metabolism is impaired, a non-ketotic hypoglycaemia may be the result, due to a break in the metabolic pathways for fatty-acid metabolism.

A triplex tetra-primer ARMS-PCR method was developed for the simultaneous detection of C677T and A1298C polymorphisms with the A66G MTRR polymorphism in a single PCR reaction.

On September 1990, the first gene therapy to combat this disease was performed by Dr. William French Anderson on a four-year-old girl, Ashanti DeSilva, at the National Institutes of Health, Bethesda, Maryland, U.S.A.

In April 2016 the Committee for Medicinal Products for Human Use of the European Medicines Agency endorsed and recommended for approval a stem cell gene therapy called Strimvelis, for children with ADA-SCID for whom no matching bone marrow donor is available.

1) Detection of orotic acid in urine

2) Deficiency of Enzymes orotate phosphoribosyl transferase and OMP decarboxylase

Low-protein food is recommended for this disorder, which requires food products low in particular types of amino acids (e.g., methionine).

A cure does not exist for I-Cell disease/Mucolipidosis II disease. Treatment is limited to controlling or reducing the symptoms that are associated with this disorder. Nutritional supplements, particularly iron and vitamin B12, are often recommended for individuals with I-Cell disease. Physical therapy to improve motor delays and speech therapy to improve language acquisition are treatment options. Surgery can remove the thin layer of corneal clouding to temporarily improve the complication. It is possible that bone marrow transplant may be helpful in delaying or correcting the neurological deterioration that occurs with I-Cell disease.. Even though there is no existing treatment, the Yash Gandhi Foundation is a 501(c)(3) non-profit organization focused on funding research for I-Cell disease

There is no treatment for MKD. But, the inflammation and the other effects can be reduced to a certain extent.

- IL-1 targeting drugs can be used to reduce the effects of the disorder. Anakinra is antagonist to IL-1 receptors. Anakinra binds the IL-1 receptor, preventing the actions of both IL-1α and IL-1β, and it has been proved to reduce the clinical and biochemical inflammation in MKD. It can effectively decreases the frequency as well as the severity of inflammatory attacks when used on a daily basis. Disadvantages with the usage of this drug are occurrence of painful injection site reaction and as the drug is discontinued in the near future the febrile attacks start. (Examined in a 12-year-old patient).

- Canakinumab is a long acting monoclonal antibody which is directed against IL-1β has shown to be effective in reducing both frequency and severity in patients suffering from mild and severe MKD in case reports and observational case series. It reduces the physiological effects but the biochemical parameter still remain elevated (Galeotti et al. demonstrated that it is more effective than anakinra –considered 6 patients suffering from MKD).

- Anti-TNF therapy might be effective in MKD, but the effect is mostly partial and therapy failure and clinical deterioration have been described frequently in patients on infliximab or etanercept. A beneficial effect of human monoclonal anti-TNFα antibody adalimumab was seen in a small number of MKD patients.

- Most MKD patients are benefited by anti-IL-1 therapy. However, anti-IL-1-resistant disease may also occur. Example. tocilizumab (a humanized monoclonal antibody against the interleukin-6 (IL-6) receptor). This drug is used when the patients are unresponsive towards Anakinra. (Shendi et al. treated a young woman in whom anakinra was ineffective with tocilizumab). It was found that it was effective in reducing the biochemical and clinical inflammation [30].Stoffels et al. observed reduction of frequency and severity of the inflammatory attacks, although after several months of treatment one of these two patients persistently showed mild inflammatory symptoms in the absence of biochemical inflammatory markers.

- A beneficial effect of hematopoietic stem cell transplantation can be used in severe mevalonate kinase deficiency conditions (Improvement of cerebral myelinisation on MRI after allogenic stem cell transplantation was observed in one girl). But, liver transplantation did not influence febrile attacks in this patient.

The main treatments for CTLN1 include a low-protein, high-calorie diet with amino acid supplements, particularly arginine. The Ucyclyd protocol, using buphenyl and ammonul, is used for treatment as well. Hyperammonemia is treated with hemodialysis; intravenous arginine, sodium benzoate, and sodium phenylacetate. In some cases, liver transplantation may be a viable treatment. L-carnitine is used in some treatment protocols.

6-Pyruvoyltetrahydropterin synthase deficiency is an autosomal recessive disorder that causes malignant hyperphenylalaninemia due to tetrahydrobiopterin deficiency.

It belongs to the rare diseases. It is a recessive disorder that is accompanied by hyperphenylalaninemia. Commonly reported symptoms are initial truncal hypotonia, subsequent appendicular hypertonia, bradykinesia, cogwheel rigidity, generalized dystonia, and marked diurnal fluctuation. Other reported clinical features include difficulty in swallowing, oculogyric crises, somnolence, irritability, hyperthermia, and seizures. Chorea, athetosis, hypersalivation, rash with eczema, and sudden death have also been reported. Patients with mild phenotypes may deteriorate if given folate antagonists such as methotrexate, which can interfere with a salvage pathway through which dihydrobiopterin is converted into tetrahydrobiopterin via dihydrofolate reductase. Treatment options include substitution with neurotransmitter precursors (levodopa, 5-hydroxytryptophan), monoamine oxidase inhibitors, and tetrahydrobiopterin. Response to treatment is variable and the long-term and functional outcome is unknown. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases their impact on the quality of life of patients, and for evaluating diagnostic and therapeutic strategies a patient registry was established by the noncommercial International Working Group on Neurotransmitter Related Disorders (iNTD).

Carnitor - an L-carnitine supplement that has shown to improve the body's metabolism in individuals with low L-carnitine levels. It is only useful for Specific fatty-acid metabolism disease.

Treatments for Glycerol Kinase Deficiency are targeted to treat the symptoms because there are no permanent treatments for this disease. The main way to treat these symptoms is by using corticosteroids, glucose infusion, or mineralocorticoids. Corticosteroids are steroid hormones that are naturally produced in the adrenal glands. These hormones regulate stress responses, carbohydrate metabolism, blood electrolyte levels, as well as other uses. The mineralocorticoids, such as aldosterone control many electrolyte levels and allow the kidneys to retain sodium. Glucose infusion is coupled with insulin infusion to monitor blood glucose levels and keep them stable.

Due to the multitude of varying symptoms of this disease, there is no specific treatment that will cure this disease altogether. The symptoms can be treated with many different treatments and combinations of medicines to try to find the correct combination to offset the specific symptoms. Everyone with Glycerol Kinase Deficiency has varying degrees of symptoms and thereby requires different medicines to be used in combination to treat the symptoms; however, this disease is not curable and the symptoms can only be managed, not treated fully.