Lecithin–cholesterol acyltransferase is an enzyme, in many animals including humans, that converts free cholesterol into cholesteryl ester, which is then sequestered into the core of a lipoprotein particle, eventually making the newly synthesized HDL spherical and forcing the reaction to become unidirectional since the particles are removed from the surface. The enzyme is bound to high-density lipoproteins (HDLs) (alpha-LCAT) and LDLs (beta-LCAT) in the blood plasma. LCAT deficiency can cause impaired vision due to cholesterol corneal opacities, anemia, and kidney damage. It belongs to the family of phospholipid:diacylglycerol acyltransferases.
N(4)-(beta-N-acetylglucosaminyl)-L-asparaginase is an enzyme that in humans is encoded by the AGA gene.
L-Arginine:glycine amidinotransferase is the enzyme that catalyses the transfer of an amidino group from L-arginine to glycine. The products are L-ornithine and glycocyamine, also known as guanidinoacetate, the immediate precursor of creatine. Creatine and its phosphorylated form play a central role in the energy metabolism of muscle and nerve tissues. Creatine is in highest concentrations in the skeletal muscle, heart, spermatozoa and photoreceptor cells. Creatine helps buffer the rapid changes in ADP/ATP ratio in muscle and nerve cells during active periods. Creatine is also synthesized in other tissues, such as pancreas, kidneys, and liver, where amidinotransferase is located in the cytoplasm, including the intermembrane space of the mitochondria, of the cells that make up those tissues.
Cathepsin A is an enzyme that is classified both as a cathepsin and a carboxypeptidase. In humans, it is encoded by the CTSA gene.
Cerebral creatine deficiencies are a small group of inherited disorders that result from defects in creatine biosynthesis and utilization. Commonly affected tissues include the brain and muscles. There are three distinct CCDs. The most common is creatine transporter defect (CTD), an X-linked disorder caused by pathogenic variants in SLC6A8. The main symptoms of CTD are intellectual disability and developmental delay, and these are caused by a lack of creatine in the brain, due to the defective transporter. There are also two enzymatic defects of creatine biosynthesis, arginine:glycine amidinotransferase deficiency, caused by variants in GATM and guanidinoacetate methyltransferase deficiency, caused by variants in GAMT. The single enzyme defects are both inherited in an autosomal recessive manner.
Sepiapterin reductase is an enzyme that in humans is encoded by the SPR gene.
Guanidinoacetate N-methyltransferase is an enzyme that catalyzes the chemical reaction and is encoded by gene GAMT located on chromosome 19p13.3.
Glycine decarboxylase also known as glycine cleavage system P protein or glycine dehydrogenase is an enzyme that in humans is encoded by the GLDC gene.
Argininosuccinate synthetase is an enzyme that in humans is encoded by the ASS1 gene.
Phosphorylase b kinase gamma catalytic chain, skeletal muscle isoform is an enzyme that in humans is encoded by the PHKG1 gene.
Creatine kinase S-type, mitochondrial is an enzyme that in humans is encoded by the CKMT2 gene.
Alpha-N-acetylgalactosaminidase is an enzyme that in humans is encoded by the NAGA gene.
Galactoside 2-alpha-L-fucosyltransferase 2 is an enzyme that in humans is encoded by the FUT2 gene. It affects the secretor status of ABO antigens.
Sodium- and chloride-dependent creatine transporter 1 is a protein that in humans is encoded by the SLC6A8 gene.
Lathosterol oxidase is a Δ7-sterol 5(6)-desaturase enzyme that in humans is encoded by the SC5D gene.
Molybdenum cofactor biosynthesis protein 1 is a protein that in humans and other animals, fungi, and cellular slime molds, is encoded by the MOCS1 gene.
Protein arginine N-methyltransferase 2 is an enzyme that in humans is encoded by the PRMT2 gene.
Peptidyl arginine deiminase, type I, also known as PADI1, is a protein which in humans is encoded by the PADI1 gene.
Glycine-N-acyltransferase, also known as GLYAT, is an enzyme which in humans is encoded by the GLYAT gene.
Arginine:glycine amidinotransferase deficiency or AGAT deficiency is an autosomal recessive cerebral creatine deficiency caused by a deficiency of the enzyme arginine:glycine amidinotransferase. This enzyme deficiency results in decreased creatine synthesis, and is caused by biallelic pathogenic variants in GATM. Individuals with AGAT deficiency are intellectually disabled and have muscle weakness. The symptoms of AGAT deficiency are caused by the lack of creatine in specific tissues, most notably muscle and brain. Oral creatine supplementation can be used to treat AGAT deficiency, with early intervention providing the best results. All creatine deficiencies are rare, and there have been fewer than 20 individuals reported in medical literature with AGAT deficiency. This disorder was first described in 2000.
