Last Updated: July 13, 2026 Introduction to Argininosuccinate Synthetase Deficiency Arginosuccinate synthetase (also identified as argininosuccinate synthase) deficiency (ASD) is an autosomal recessive disorder of the urea cycle that also affects the synthesis of...
Last Updated: July 13, 2026 Introduction to OTC Deficiency Deficiencies in each of the enzymes of the urea cycle have been identified. Collectively, these enzyme deficiencies lead to a family of disorders referred to as the urea cycle disorders (UCD). The most...
Last Updated: July 13, 2026 Introduction to CPS1 Deficiency Carbamoyl phosphate synthetase 1 deficiency (CPSD) is an autosomal recessive disorder that, as the name implies, is due to pathogenic variants in the gene (CPS1) encoding the urea cycle enzyme, carbamoyl...
Last Updated: July 13, 2026 Introduction to the Urea Cycle Disorders (UCD) A complete lack of any one of the enzymes of the urea cycle is associated with an significant increase in the likelihood for death shortly after birth. Nonetheless, deficiencies in each of the...
Last Updated: July 13, 2026 Introduction to Phenylketonuria: PKU Phenylketonuria (PKU) is an autosomal recessive disorder associated with hyperphenylalaninemia that results from defects in the metabolism of phenylalanine. PKU represents the most severe form of the...
Last updated: July 13, 2026 Introduction to Maple Syrup Urine Disease: MSUD Maple syrup urine disease (MSUD), also called branched-chain aminoaciduria, is so called because the urine of affected individuals smells like maple syrup or burnt sugar. The cause of the odor...
Last Updated: July 13, 2026 Introduction of Homocyst(e)inemia/Homocyst(e)inuria Homocysteinemias (homocystinemias) represent a family of autosomal recessive disorders resulting from defects in several of the genes involved in the conversion of methionine to cysteine....
Last Updated: July 13, 2026 Introduction to Hartnup Disorder Hartnup disorder is an autosomal recessive disorder that was first described in 1956 in the Hartnup family in London. The originally characterized patients exhibited a renal aminoaciduria of neutral amino...
Last Updated: July 13, 2026 Introduction to Cystinuria As the name implies, cystinuria is a disorder associated with excess cystine in the urine. Cystine is the oxidized disulfide homodimer of two cysteines. Type I cystinuria is an autosomal recessive disorder that...
Last Updated: July 13, 2026 Introduction to Alkaptonuria Alkaptonuria is a rare autosomal recessive inherited disorder caused by defects in the gene encoding an enzyme, homogentisic acid oxidase, involved in the catabolism of phenylalanine and tyrosine. As a...