Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nonketotic hyperglycinemia (NKH) is an autosomal recessive hereditary disease caused by a defect in the glycine cleavage system and is classified into typical and atypical NKH. Atypical NKH has complex manifestations and is difficult to diagnose in clinical practice. This article reports a family of NKH. The parents had normal phenotypes, and the older brother and the younger sister developed this disease in the neonatal period. The older brother manifested as intractable epilepsy, severe spastic diplegia, intellectual disability, an increased level of glycine in blood and cerebrospinal fluid, an increased glycine/creatinine ratio in urine, and an increased ratio of glycine concentration in cerebrospinal fluid and blood. The younger sister manifested as delayed language development, ataxia, chorea, mental and behavior disorders induced by pyrexia, hypotonia, an increased level of glycine in cerebrospinal fluid, and an increased ratio of glycine concentration in cerebrospinal fluid and blood. High-throughput sequencing found a maternal missense mutation, c.3006C>G (p.C1002W), and a paternal nonsense mutation, c.1256C>G (p.S419X), in the GLDC gene in both patients. These two mutations were thought to be pathogenic mutations by a biological software. H293T cells transfected with these two mutants of the GLDC gene had a down-regulated activity of glycine decarboxylase. NKH has various phenotypes, and high-throughput sequencing helps to make a confirmed diagnosis. Atypical NKH is associated with the downregulated activity of glycine decarboxylase caused by gene mutations.
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PMID:[Clinical and genetic analyses of a family with atypical nonketotic hyperglycinemia caused by compound heterozygous mutations in the GLDC gene]. 2904 6

Nonketotic hyperglycinemia (NKH) is a devastating inborn error of glycine metabolism caused by deficient activity of the glycine cleavage enzyme. Classically, patients present with lethargy, hypotonia, myoclonic jerks, transient respiratory depression in the first week of life and often progress to death. Surviving infants have profound psychomotor retardation, refractory epilepsy and poor quality of life. Currently, no effective therapeutic avenues exist for severe NKH. Ketogenic diet (KD) has been trialled only in a small group of patients with neonatal NKH and early myoclonic encephalopathy, in whom significant improvements in seizure control were reported. We describe an infant with classical neonatal NKH who presented on the third day of life with hypotonia, poor feeding, respiratory insufficiency resulting in ventilatory support and seizures with burst-suppression pattern on electroencephalogram (EEG). KD initiated at age 6 months for intractable seizures, lead to a dramatic decrease in seizure frequency, EEG improvements, normalisation of plasma glycine levels, reduced spasticity and improved quality of life. KD may be a valuable treatment modality for refractory seizure control in classical NKH.
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PMID:Ketogenic diet, a potentially valuable therapeutic option for the management of refractory epilepsy in classical neonatal nonketotic hyperglycinemia: a case report. 3010 80

Nonketotic hyperglycinemia (NKH) or glycine encephalopathy is an autosomal recessive disorder of glycine metabolism resulting in an excessive accumulation of glycine in all body tissues, including the central nervous system. It is caused by a biochemical defect in the glycine cleavage system and considered as a rare disorder with an estimated prevalence of 1:60,000. The neonatal form presents in the first few days of life with progressive encephalopathy, hypotonia, myoclonic jerks, hiccups, seizures, rapid progression to coma and often death due to central apnea. Surviving infants often have severe developmental delay and refractory seizures. Atypical forms of NKH present with heterogeneous and nonspecific disease course. Classical glycine encephalopathy usually carries a very poor prognosis. We describe two neonates who presented with neonatal encephalopathy, apnea, and progressive lethargy. Increased CSF glycine level along with an elevated CSF to plasma glycine ratio was suggestive of classic NKH. Burst suppression EEG and agenesis of the corpus callosum were supportive findings. Evolution of the EEG patterns and course of the disease are discussed in detail. Transient phases of clinical stabilization and normalized plasma biochemical results may not necessarily reflect the actual encephalopathic process. Serial EEGs are helpful to assess the efficacy of treatment and to modify the therapeutic approach.
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PMID:Nonketotic Hyperglycinemia: Two Case Reports and Review. 3143 33


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