5α-Reductase 2 deficiency (5αR2D) is an autosomal recessive condition caused by a mutation in SRD5A2, a gene encoding the enzyme 5α-reductase type 2 (5αR2). The condition is rare, affects only genetic males, and has a broad spectrum.
Alkaptonuria is a rare inherited genetic disease which is caused by a mutation in the HGD gene for the enzyme homogentisate 1,2-dioxygenase ; if a person inherits an abnormal copy from both parents, the body accumulates an intermediate substance called homogentisic acid in the blood and tissues. Homogentisic acid and its oxidized form alkapton are excreted in the urine, giving it an unusually dark color. The accumulating homogentisic acid causes damage to cartilage and heart valves, as well as precipitating as kidney stones and stones in other organs. Symptoms usually develop in people over 30 years old, although the dark discoloration of the urine is present from birth.
Xylitol is a chemical compound with the formula C
5H
12O
5, or HO(CH2)(CHOH)3(CH2)OH; specifically, one particular stereoisomer with that structural formula. It is a colorless or white crystalline solid that is freely soluble in water. It is classified as a polyalcohol and a sugar alcohol, specifically an alditol. The name derives from Ancient Greek: ξύλον, xyl[on] 'wood', with the suffix -itol used to denote it being a sugar alcohol.
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.
Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances (substrates) into others (products). In most of the disorders, problems arise due to accumulation of substances which are toxic or interfere with normal function, or due to the effects of reduced ability to synthesize essential compounds. Inborn errors of metabolism are often referred to as congenital metabolic diseases or inherited metabolic disorders. Another term used to describe these disorders is "enzymopathies". This term was created following the study of biodynamic enzymology, a science based on the study of the enzymes and their products. Finally, inborn errors of metabolism were studied for the first time by British physician Archibald Garrod (1857–1936), in 1908. He is known for work that prefigured the "one gene–one enzyme" hypothesis, based on his studies on the nature and inheritance of alkaptonuria. His seminal text, Inborn Errors of Metabolism, was published in 1923.
Xylulose is a ketopentose, a monosaccharide containing five carbon atoms, and including a ketone functional group. It has the chemical formula C5H10O5. In nature, it occurs in both the L- and D-enantiomers. 1-Deoxyxylulose is a precursor to terpenes via the DOXP pathway.
Sir Archibald Edward Garrod was an English physician who pioneered the field of inborn errors of metabolism. He also discovered alkaptonuria, understanding its inheritance. He served as Regius Professor of Medicine at the University of Oxford from 1920 to 1927.
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.
Ribose 5-phosphate (R5P) is both a product and an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the production of ribulose 5-phosphate. Depending on the body's state, ribulose 5-phosphate can reversibly isomerize to ribose 5-phosphate. Ribulose 5-phosphate can alternatively undergo a series of isomerizations as well as transaldolations and transketolations that result in the production of other pentose phosphates as well as fructose 6-phosphate and glyceraldehyde 3-phosphate.
Dicarbonyl/L-xylulose reductase, also known as carbonyl reductase II, is an enzyme that in human is encoded by the DCXR gene located on chromosome 17.
Fructokinase, also known as D-fructokinase or D-fructose (D-mannose) kinase, is an enzyme of the liver, intestine, and kidney cortex. Fructokinase is in a family of enzymes called transferases, meaning that this enzyme transfers functional groups; it is also considered a phosphotransferase since it specifically transfers a phosphate group. Fructokinase specifically catalyzes the transfer of a phosphate group from adenosine triphosphate to fructose as the initial step in its utilization. The main role of fructokinase is in carbohydrate metabolism, more specifically, sucrose and fructose metabolism. The reaction equation is as follows:
Essential fructosuria, caused by a deficiency of the enzyme hepatic fructokinase, is a clinically benign condition characterized by the incomplete metabolism of fructose in the liver, leading to its excretion in urine. Fructokinase is the first enzyme involved in the degradation of fructose to fructose-1-phosphate in the liver.
D-Xylose is a five-carbon aldose that can be catabolized or metabolized into useful products by a variety of organisms.
In enzymology, a D-xylulose reductase (EC 1.1.1.9) is an enzyme that is classified as an Oxidoreductase (EC 1) specifically acting on the CH-OH group of donors (EC 1.1.1) that uses NAD+ or NADP+ as an acceptor (EC 1.1.1.9). This enzyme participates in pentose and glucuronate interconversions; a set of metabolic pathways that involve converting pentose sugars and glucuronate into other compounds.
Ribose-5-phosphate isomerase (Rpi) encoded by the RPIA gene is an enzyme that catalyzes the conversion between ribose-5-phosphate (R5P) and ribulose-5-phosphate (Ru5P). It is a member of a larger class of isomerases which catalyze the interconversion of chemical isomers. It plays a vital role in biochemical metabolism in both the pentose phosphate pathway and the Calvin cycle. The systematic name of this enzyme class is D-ribose-5-phosphate aldose-ketose-isomerase.
Inborn errors of carbohydrate metabolism are inborn error of metabolism that affect the catabolism and anabolism of carbohydrates.
Transaldolase deficiency is a disease characterised by abnormally low levels of the transaldolase enzyme. It is a metabolic enzyme involved in the pentose phosphate pathway. It is caused by mutation in the transaldolase gene (TALDO1). It was first described by Verhoeven et al. in 2001.
Ribose-5-phosphate isomerase deficiency (RPID) is a rare human disorder caused by mutations in ribose-5-phosphate isomerase, an enzyme of the pentose phosphate pathway. With only four known cases – all diagnosed between 1984 and 2019 – RPI deficiency is the second rarest disease, with Fields condition being the rarest, affecting two known individuals, Catherine and Kirstie Fields.
D-Glyceric Acidemia is an inherited disease, in the category of inborn errors of metabolism. It is caused by a mutation in the gene GLYCTK, which encodes for the enzyme glycerate kinase.
Creatine transporter deficiency (CTD) is an inborn error of creatine metabolism in which creatine is not properly transported to the brain and muscles due to defective creatine transporters. CTD is an X-linked disorder caused by mutation in SLC6A8. SLC6A8 is located at Xq28. Hemizygous males with CTD express speech and behavior abnormalities, intellectual disabilities, development delay, seizures, and autistic behavior. Heterozygous females with CTD generally express fewer, less severe symptoms. CTD is one of three different types of cerebral creatine deficiency (CCD). The other two types of CCD are guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency. Clinical presentation of CTD is similar to that of GAMT and AGAT deficiency. CTD was first identified in 2001 with the presence of a hemizygous nonsense change in SLC6A8 in a male patient.
