Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also result in a musty smell and lighter skin. A baby born to a mother who has poorly treated PKU may have heart problems, a small head, and low birth weight.
Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name biotin, borrowed from the German Biotin, derives from the Ancient Greek word βίοτος (bíotos; 'life') and the suffix "-in" (a suffix used in chemistry usually to indicate 'forming'). Biotin appears as a white, needle-like crystalline solid.
Galactosemia is a rare genetic metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly. Galactosemia follows an autosomal recessive mode of inheritance that confers a deficiency in an enzyme responsible for adequate galactose degradation.
Methylmalonic acidemias, also called methylmalonic acidurias, are a group of inherited metabolic disorders, that prevent the body from properly breaking down proteins and fats. This leads to a buildup of a toxic level of methylmalonic acid in body liquids and tissues. Due to the disturbed branched-chain amino acids (BCAA) metabolism, they are among the classical organic acidemias.
Glycogen storage disease type II(GSD-II), also called Pompe disease, and formerly known as GSD-IIa or Limb–girdle muscular dystrophy2V, is an autosomal recessive metabolic disorder which damages muscle and nerve cells throughout the body. It is caused by an accumulation of glycogen in the lysosome due to deficiency of the lysosomal acid alpha-glucosidase enzyme (GAA). The inability to breakdown glycogen within the lysosomes of cells leads to progressive muscle weakness throughout the body and affects various body tissues, particularly in the heart, skeletal muscles, liver and the nervous system.
Isovaleric acidemia is a rare autosomal recessive metabolic disorder which disrupts or prevents normal metabolism of the branched-chain amino acid leucine. It is a classical type of organic acidemia.
Maple syrup urine disease (MSUD) is a rare, inherited metabolic disorder that affects the body’s ability to metabolize amino acids due to a deficiency in the activity of the branched-chain alpha-ketoacid dehydrogenase (BCKAD) complex. It particularly affects the metabolism of amino acids- leucine, isoleucine, and valine. With MSUD, the body is not able to properly break down these amino acids, therefore leading to the amino acids to build up in urine and become toxic. The condition gets its name from the distinctive sweet odor of affected infants' urine and earwax due to the buildup of these amino acids.
Holocarboxylase synthetase deficiency is an inherited metabolic disorder in which the body is unable to use the vitamin biotin effectively. This disorder is classified as a multiple carboxylase deficiency, a group of disorders characterized by impaired activity of certain enzymes that depend on biotin. Symptoms are very similar to biotinidase deficiency and treatment – large doses of biotin – is also the same.
Tyrosinemia or tyrosinaemia is an error of metabolism, usually inborn, in which the body cannot effectively break down the amino acid tyrosine. Symptoms of untreated tyrosinemia include liver and kidney disturbances. Without treatment, tyrosinemia leads to liver failure. Today, tyrosinemia is increasingly detected on newborn screening tests before any symptoms appear. With early and lifelong management involving a low-protein diet, special protein formula, and sometimes medication, people with tyrosinemia develop normally, are healthy, and live normal lives.
Tetrahydrobiopterin deficiency (THBD, BH4D) is a rare metabolic disorder that increases the blood levels of phenylalanine. Phenylalanine is an amino acid obtained normally through the diet, but can be harmful if excess levels build up, causing intellectual disability and other serious health problems. In healthy individuals, it is metabolised (hydroxylated) into tyrosine, another amino acid, by phenylalanine hydroxylase. However, this enzyme requires tetrahydrobiopterin as a cofactor and thus its deficiency slows phenylalanine metabolism.
Holocarboxylase synthetase ), also known as protein—biotin ligase, is a family of enzymes. This enzyme is important for the effective use of biotin, a B vitamin found in foods such as liver, egg yolks, and milk. In many of the body's tissues, holocarboxylase synthetase activates other specific enzymes by attaching biotin to them. These carboxylases are involved in many critical cellular functions, including the production and breakdown of proteins, fats, and carbohydrates.
3-Methylcrotonyl-CoA carboxylase deficiency also known as 3-Methylcrotonylglycinuria is an inborn error of leucine metabolism and is inherited through an autosomal recessive fashion. 3-Methylcrotonyl-CoA carboxylase deficiency is caused by mutations in the MCCC1 gene, formerly known as MMCA, or the MCCC2 gene, formerly known as MCCB. MCCC1 encodes the a-subunits of 3-methylcrotonyl-CoA carboxylase while MCCC2 encodes the b-subunits. The clinical presentation of 3-Methylcrotonyl-CoA carboxylase deficiency is varied, even within members of the same family.
Pyruvate carboxylase deficiency is an inherited disorder that causes lactic acid to accumulate in the blood. High levels of these substances can damage the body's organs and tissues, particularly in the nervous system. Pyruvate carboxylase deficiency is a rare condition, with an estimated incidence of 1 in 250,000 births worldwide. Type A of the disease appears to be much more common in some Algonkian Indian tribes in eastern Canada, while the type B disease is more present in European populations.
Methylcrotonyl CoA carboxylase is a biotin-requiring enzyme located in the mitochondria. MCC uses bicarbonate as a carboxyl group source to catalyze the carboxylation of a carbon adjacent to a carbonyl group performing the fourth step in processing leucine, an essential amino acid.
Biotinidase, also known as biotinase, is an enzyme that in humans is encoded by the BTD gene.
ACADSB is a human gene that encodes short/branched chain specific acyl-CoA dehydrogenase (SBCAD), an enzyme in the acyl CoA dehydrogenase family.
Galactose-1-phosphate uridylyltransferase deficiency(classic galactosemia) is the most common type of galactosemia, an inborn error of galactose metabolism, caused by a deficiency of the enzyme galactose-1-phosphate uridylyltransferase. It is an autosomal recessive metabolic disorder that can cause liver disease and death if untreated. Treatment of galactosemia is most successful if initiated early and includes dietary restriction of lactose intake. Because early intervention is key, galactosemia is included in newborn screening programs in many areas. On initial screening, which often involves measuring the concentration of galactose in blood, classic galactosemia may be indistinguishable from other inborn errors of galactose metabolism, including galactokinase deficiency and galactose epimerase deficiency. Further analysis of metabolites and enzyme activities are needed to identify the specific metabolic error.
Biotin deficiency is a nutritional disorder which can become serious, even fatal, if allowed to progress untreated. It can occur in people of any age, ancestry, or of either sex. Biotin is part of the B vitamin family. Biotin deficiency rarely occurs among healthy people because the daily requirement of biotin is low, many foods provide adequate amounts of it, intestinal bacteria synthesize small amounts of it, and the body effectively scavenges and recycles it in the kidneys during production of urine.
Multiple carboxylase deficiency is a form of metabolic disorder involving failures of carboxylation enzymes.
Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare disease that affects the nervous system, particularly the basal ganglia in the brain. It is a treatable neurometabolic disorder with autosomal recessive inheritance. First described in 1998 and then genetically distinguished in 2005, the disease is characterized by progressive brain damage that, if left untreated, can lead to coma and/or death. Commonly observed in individuals with BTBGD is recurring subacute encephalopathy along with confusion, seizures, and disordered movement (hypokinesia).
