1/6. Human glycine decarboxylase gene (GLDC) and its highly conserved processed pseudogene (psiGLDC): their structure and expression, and the identification of a large deletion in a family with nonketotic hyperglycinemia.Mutations in the glycine decarboxylase gene (GLDC) cause nonketotic hyperglycinemia (NKH), an in-born error of metabolism characterized by severe neurological disturbance. We have determined the structure of GLDC and of its pseudogene (psiGLDC) and studied their expression for a molecular analysis of NKH. The GLDC gene spans at least 135 kb and consists of 25 exons. All donor and acceptor sites adhere to the canonical GT-AG rule, except for the donor site of intron 21, where a variant form GC is used instead of GT. The transcription initiation site has been assigned to a residue 163 bp upstream from the translation initiation triplet by primer extension analysis. The psiGLDC gene has no intron and shares 97.5% homology with the coding region of functional GLDC, suggesting that psiGLDC is a processed pseudogene that arose from the GLDC transcript about 4-8 million years ago. rna blotting analysis has revealed that GLDC is expressed in human liver, kidney, brain, and placenta. We have also examined a patient with NKH with no detectable GLDC mRNA in his lymphoblasts. exons 1-3 of the functional GLDC gene from this patient are not amplified by polymerase chain reaction (PCR), whereas those from control subjects are. These results suggest a large homozygous deletion (at least 30 kb) in the patient. Furthermore, we have devised a semi-quantitative PCR to estimate the number of GLDC alleles by using psiGLDC as an internal control and have confirmed the homozygosity and heterozygosity of the deletion in the patient and his parents, respectively. Structural information of GLDC and psiGLDC should facilitate the molecular analysis of NKH.- - - - - - - - - - ranking = 1keywords = metabolism, error (Clic here for more details about this article) |
2/6. acrodermatitis enteropathica-like eruption in an infant with nonketotic hyperglycinemia.acrodermatitis enteropathica is a rare inherited disorder characterized by zinc deficiency and a triad of dermatitis, diarrhea, and alopecia. It is an autosomal recessive condition thought to be due to the inability to absorb zinc from the gastrointestinal tract. Acquired zinc deficiency due to a variety of etiologies may produce a similar clinical picture. These causes include inadequate supply, malabsorption, and low zinc stores. In addition to zinc, deficiencies of other nutrients such as branched chain amino acids have induced an acrodermatitis enteropathica-like eruption. We describe a case of a 26-month-old boy with a rare inborn error of metabolism known as nonketotic hyperglycinemia who developed an acrodermatitis enteropathica-like eruption. In addition to zinc deficiency, the patient was deficient in branched chain amino acids due to a low protein diet instituted to reduce his elevated glycine levels. The rash did not respond to zinc replacement alone, and therefore is most likely a combination of amino acid and zinc deficiency. acrodermatitis enteropathica-like eruptions have been described in other conditions that cause decreased serum amino acids, such as maple syrup urine disease and organic acidurias. This is the first case describing an association between acrodermatitis enteropathica and nonketotic hyperglycinemia.- - - - - - - - - - ranking = 11.720547674636keywords = inborn error, metabolism, error (Clic here for more details about this article) |
3/6. In vivo 1H magnetic resonance spectroscopic measurement of brain glycine levels in nonketotic hyperglycinemia.Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder of glycine metabolism. Defective glycine cleavage causes elevated concentrations of glycine in plasma, urine, and cerebrospinal fluid. A longitudinal study using magnetic resonance imaging (MRI) and single-voxel 1H magnetic resonance spectroscopy (MRS) was performed on an infant with the typical clinical picture of NKH. He was examined twice during the course of treatment with sodium benzoate and dextromethorphan. At the age of 10 months, MRI showed normal brain structure, while MRS detected a prominent glycine peak in the brain. Repeat MRS at the age of 13 months showed a small increase in glycine peak and a prominent glutamate/glutamine peak not previously detected. The MRS measurements were consistent with the slight increase in blood glycine level and the elevation in glutamine level, indicating that 1HMRS can be a valuable tool in the diagnosis and monitoring of treatment effects in patients with NKH.- - - - - - - - - - ranking = 0.84510727119301keywords = metabolism (Clic here for more details about this article) |
4/6. Detection of mutations in the glycine decarboxylase gene in patients with nonketotic hyperglycinaemia.Nonketotic hyperglycinaemia (NKH) is an autosomal recessive disorder of glycine metabolism caused by a deficiency in the mitochondrial glycine cleavage enzyme. The majority of cases are caused by mutations in the P-protein, one of the four components of the glycine cleavage enzyme, also known as glycine decarboxylase (GLDC). Previous studies searching for causative mutations in NKH patients have only looked for a limited number of specific mutations or only screened part of the gene, and in many cases either no mutation or only one mutation was found, which is of limited use for prenatal diagnosis. In this study, we describe the screening of the entire GLDC gene in 3 NKH families by D-HPLC analysis of all 25 exons, identifying two point mutations and two large deletions (exon 8 and exons 2-15) using a combination of D-HPLC analysis, long range PCR, Southern blot and sequencing. For complete prenatal testing both mutations need to be identified, and we suggest that screening of the entire gene as well as deletional analysis should be considered in those subjects where only one mutation has been identified.- - - - - - - - - - ranking = 0.84510727119301keywords = metabolism (Clic here for more details about this article) |
5/6. Four cases of neonatal non-ketotic hyperglycinaemia.Non-ketotic hyperglycinaemia is an autosomal recessive disorder of glycine metabolism caused by a defect in the glycine cleavage system. Affected neonates present with lethargy, feeding difficulty, hypotonia, apnoea, poorly controlled convulsions and coma. Four cases are reported, three of whom died in the neonatal period. The fourth case was treated with dextromethorphan and sodium benzoate. He survived with neurodevelopmental delay but is now almost seizure-free.- - - - - - - - - - ranking = 0.84510727119301keywords = metabolism (Clic here for more details about this article) |
6/6. Valproate-induced chorea and encephalopathy in atypical nonketotic hyperglycinemia.Nonketotic hyperglycinemia is a disorder of amino acid metabolism in which a defect in the glycine cleavage system leads to an accumulation of glycine in the brain and other body compartments. In the classical form it presents as neonatal apnea, intractable seizures, and hypotonia, followed by significant psychomotor retardation. An important subset of children with nonketotic hyperglycinemia are atypical variants who present in a heterogeneous manner. This report describes a patient with mild language delay and mental retardation, who was found to have nonketotic hyperglycinemia following her presentation with acute encephalopathy and chorea shortly after initiation of valproate therapy.- - - - - - - - - - ranking = 0.84510727119301keywords = metabolism (Clic here for more details about this article) |