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

A 4-year-old patient is described with hyperphenylalaninemia, severe retardation in development, severe muscular hypotonia of the trunk and hypertonia of the extremities, convulsions, and frequent episodes of hyperthermia without infections. Urinary excretion of neopterin, biopterin, pterin, isoxanthopterin, dopamine, and serotonin was very low, although the relative proportions of pterins were normal. In lumbar cerebrospinal fluid, homovanillic acid, 5-hydroxyindoleacetic acid, neopterin and biopterin were low. Oral administration of L-erythro tetrahydrobiopterin normalized the elevated serum phenylalanine within 4 h, serum tyrosine was increased briefly and serum alanine and glutamic acid for a longer time. Urinary dopamine and serotonin excretion were also increased. Administration of an equivalent dose of D-erythro tetrahydroneopterin was ineffective and demonstrated that this compound is not a cofactor in vivo and cannot be transformed into an active cofactor. GTP cyclohydrolase I activity was not detectable in liver biopsies from the patient. The presence of an endogenous inhibitor in the patient's liver was excluded. This is the first case of a new variant of hyperphenylalaninemia in which the formation of dihydroneopterin triphosphate and its pterin metabolites in liver is markedly diminished. Normal activities of xanthine oxidase and sulfite oxidase were apparent since uric acid levels were normal and no increase in hypoxanthine, xanthine, and S-sulfocysteine concentrations could be observed in urine. It is concluded that the molybdenum cofactor of these enzymes may not be derived from dihydroneopterin triphosphate in man. Also, since no gross abnormalities in the patient's immune system could be found, it seems unlikely that dihydroneopterin triphosphate metabolites, such as neopterin, participate actively in immunological processes, as postulated by others. See Note added in proof.
 ...
PMID:GTP cyclohydrolase I deficiency, a new enzyme defect causing hyperphenylalaninemia with neopterin, biopterin, dopamine, and serotonin deficiencies and muscular hypotonia. 673 69

Aromatic L-amino acid decarboxylase deficiency is an inborn error of metabolism that leads to combined serotonin and catecholamine deficiency, first described by Hyland et al in 1990. The clinical features, biochemical findings, and treatment of the second family with this condition are reported. Our male patient presented with developmental delay, extreme hypotonia, oculogyric crises, and irritability. The diagnosis of this inborn error of biogenic amine metabolism was accomplished by determining low concentrations of homovanillic, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenyl-ethyleneglycol in cerebrospinal fluid with normal biopterin metabolism and increased L-dopa, in plasma, cerebrospinal fluid, and urine. Greatly reduced activity of aromatic L-amino acid decarboxylase in plasma confirmed this diagnosis. Combined treatment with pyridoxine, tranylcypromine, and bromocriptine produced some clinical improvement.
 ...
PMID:Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a second family. 930 16

Tetrahydrobiopterin (BH4) deficiencies are a heterogeneous group of disorders caused by a defect in two of the three enzymes involved in its biosynthesis or in the two recycling enzymes. Except for the deficiency of dehydratase, an enzyme catalyzing a reaction in the recycling pathway, all other variants of BH4 deficiency are characterized by developmental delay, progressive neurological deterioration, hypokinesis, drooling, swallowing difficulty, truncal hypotonia, increased limb tone, myoclonus and brisk deep tendon reflexes. A deficiency of guanosine triphosphate cyclohydrolase I (GTPCH), the first enzyme in the biosynthetic pathway of BH4, is described in a 14-month-old male infant with hyperphenylalaninemia, developmental delay, hypertonia of the extremities, seizures, feeding difficulties, and vomiting. Urinary pteridine screening revealed very low levels of neopterin and biopterin which was highly suggestive of GTPCH deficiency. Low cerebrospinal fluid concentrations of 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid concentrations, together with no detectable neopterin and decreased concentrations of biopterin and folate, agreed with the diagnosis of GTPCH deficiency. Subsequently measured neopterin and biopterin synthesis in cytokine-stimulated skin fibroblasts confirmed GTPCH deficiency, albeit indirectly. The patient showed marked improvement on a low-protein low-phenylalanine diet with neurotransmitter precursor administration. The favorable outcome in this patient clearly shows that not only newborns with elevated phenylalanine levels but also older children with neurological signs and symptoms should be screened for a BH4 deficiency in order to have maximum benefit of the treatment.
 ...
PMID:Guanosine triphosphate cyclohydrolase I deficiency: a rare cause of hyperphenylalaninemia. 1077 Jun 63

The diagnosis of a 14-year-old girl with a new homoallelic mutation in the sepiapterin reductase (SR) gene is reported. Initially she presented at the age of 2 with hypotonia and mild cognitive developmental delay, and was diagnosed as having mild methylmalonic aciduria, which was recently identified as methylmalonylCoA racemase deficiency, a new defect in valine-isoleucine metabolism. After a 12-year progression of her neurologic condition, which had made her wheelchair-bound at the age of 6, dystonia with diurnal variation had become apparent. At the age of 14 this finding led to rapid diagnosis of SR deficiency. The diagnostic approach with CSF neurotransmitter and pterins analysis and combined phenylalanine/BH(4) loading test, and finally measurement of sepiapterin in CSF is illustrative for the diagnosis of SR deficiency. As in all other patients with this new defect, very low levels of homovanillic acid and 5-hydroxyindoleacetic acid and high levels of biopterin and sepiapterin in the CSF are the diagnostic hallmark. The girl improved dramatically on treatment with L-DOPA and 5-hydroxytryptophan. The initial diagnosis of methylmalonic aciduria may afterwards be considered to have not significantly contributed to her clinical condition and only has led to a long delay of the clinically relevant diagnosis of SR deficiency. Although the clinical condition of this recently recognized autosomal recessive defect in pterin metabolism is complex and many symptoms can occur in variable severity and time of onset, dystonia with diurnal variation is a characteristic finding, as shown in nearly all patients described so far. The rapid and favourable response on treatment with L-DOPA warrants the classification of SR deficiency as another autosomal recessive type of DOPA-responsive dystonia (DRD). This classification is important to improve the awareness of clinicians that more than one metabolic defect can underlie the phenotype of a DOPA-responsive dystonic disorder and that dystonia should always trigger a rapid diagnosis of the underlying neurotransmitter synthesis defect, in view of the excellent treatability of a DRD.
 ...
PMID:Sepiapterin reductase deficiency an autosomal recessive DOPA-responsive dystonia. 1665 Jul 84

Autosomal recessive guanosine triphosphate cyclohydrolase (GTPCH) type I deficiency is characterized by complex neurological dysfunction. Patients are usually diagnosed with hyperphenylalaninemia in newborn screening. We describe two unrelated patients without hyperphenylalaninemia who presented during early infancy with severe motor retardation, hypokinesia, and truncal hypotonia. CSF homovanillic acid and 5-hydroxyindoleacetic acid as well as tetrahydrobiopterin and neopterin were decreased. Diagnosis of recessive GTPCH deficiency was confirmed biochemically, and a novel homozygous mutation was identified in one patient and a compound-heterozygous mutation of GCH1 in the other. Treatment with Levodopa/Carbidopa resulted in striking clinical improvement, with age-appropriate development at follow-up at 6 years. Autosomal recessive GTPCH deficiency should be considered in infants with severe truncal hypotonia even if hyperphenylalaninemia or classical extrapyramidal symptoms are missing. Neurotransmitter analysis followed by enzyme or mutation analysis can confirm the diagnosis, and Levodopa treatment should be started at high-doses.
 ...
PMID:Clinical and biochemical characterization of patients with early infantile onset of autosomal recessive GTP cyclohydrolase I deficiency without hyperphenylalaninemia. 2081 8

Two male siblings from a consanguineous union presented in early infancy with marked truncal hypotonia, a general paucity of movement, extrapyramidal signs and cognitive delay. By mid-childhood they had made little developmental progress and remained severely hypotonic and bradykinetic. They developed epilepsy and had problems with autonomic dysfunction and oculogyric crises. They had a number of orthopaedic problems secondary to their hypotonia. Cerebrospinal fluid (CSF) neurotransmitters were initially normal, apart from mildly elevated 5-hydroxyindolacetic acid, and the children did not respond favourably to a trial of levodopa-carbidopa. The youngest died from respiratory complications at 10 years of age. Repeat CSF neurotransmitters in the older sibling at eight years of age showed slightly low homovanillic acid and 5-hydroxyindoleacetic acid levels. Whole-exome sequencing revealed a novel mutation homozygous in both children in the monoamine transporter gene SLC18A2 (p.Pro237His), resulting in brain dopamine-serotonin vesicular transport disease. This is the second family to be described with a mutation in this gene. Treatment with the dopamine agonist pramipexole in the surviving child resulted in mild improvements in alertness, communication, and eye movements. This case supports the identification of the causal mutation in the original case, expands the clinical phenotype of brain dopamine-serotonin vesicular transport disease and confirms that pramipexole treatment may lead to symptomatic improvement in affected individuals.
 ...
PMID:Brain dopamine-serotonin vesicular transport disease presenting as a severe infantile hypotonic parkinsonian disorder. 2649 64

We describe neurotransmitter abnormalities in two patients with drug-resistant epilepsy resulting from deleterious de novo mutations in sodium channel genes. Whole exome sequencing identified a de novo SCN2A splice-site mutation (c.2379+1G>A, p.Glu717Gly.fs*30) resulting in deletion of exon 14, in a 10-year old male with early onset global developmental delay, intermittent ataxia, autism, hypotonia, epileptic encephalopathy and cerebral/cerebellar atrophy. In the cerebrospinal fluid both homovanillic acid and 5-hydroxyindoleacetic acid were significantly decreased; extensive biochemical and genetic investigations ruled out primary neurotransmitter deficiencies and other known inborn errors of metabolism. In an 8-year old female with an early onset intractable epileptic encephalopathy, developmental regression, and progressive cerebellar atrophy, a previously unreported de novo missense mutation was identified in SCN8A (c.5615G>A; p.Arg1872Gln), affecting a highly conserved residue located in the C-terminal of the Nav1.6 protein. Aside from decreased homovanillic acid and 5-hydroxyindoleacetic acid, 5-methyltetrahydrofolate was also found to be low. We hypothesize that these channelopathies cause abnormal synaptic mono-amine metabolite secretion/uptake via impaired vesicular release and imbalance in electrochemical ion gradients, which in turn aggravate the seizures. Treatment with oral 5-hydroxytryptophan, l-Dopa/Carbidopa, and a dopa agonist resulted in mild improvement of seizure control in the male case, most likely via dopamine and serotonin receptor activated signal transduction and modulation of glutamatergic, GABA-ergic and glycinergic neurotransmission. Neurotransmitter analysis in other sodium channelopathy patients will help validate our findings, potentially yielding novel treatment opportunities.
...
PMID:Secondary neurotransmitter deficiencies in epilepsy caused by voltage-gated sodium channelopathies: A potential treatment target? 2918 79

Hereditary dopamine transporter deficiency syndrome (DTDS) is a neurotransmitter disorder caused by a defect in the neuronal uptake of dopamine. To date, 20 patients are reported in the literature, and we present 2 additional patients with DTDS harboring novel homozygous SLC6A3 gene mutations. Patient A is an 8-month-old male with neonatal-onset hypotonia, who developed orolingual dyskinetic movements and oculogyric crises after 4 months of age, with evolution to status dystonicus episodes. Patient B is a 4-year-old male who also had hypotonia since birth, with additional severe limb contractions and oculogyric crises after the age of 3 months, with a misdiagnosis of epileptic encephalopathy. Both patients had consanguineous parents and similar cerebrospinal fluid (CSF) neurotransmitter profiles with elevated homovanillic acid and increased the ratio of homovanillic acid to 5-hydroxyindoleacetic acid. Diagnostic delay is 4 months, and 3 years 9 months, respectively. Treatment response to levodopa is poor. Early infantile-onset progressive dystonia with oculogyric crises, hypotonia, developmental delay, and CSF neurotransmitter profile led to a diagnosis of DTDS in these two patients. Management of hyperkinetic movement disorder, status dystonicus, and feeding difficulties are challenging. Detailed phenotyping of individual patients along with treatment response should provide insight into dopamine homeostasis.
 ...
PMID:Hereditary Dopamine Transporter Deficiency Syndrome: Challenges in Diagnosis and Treatment. 2769 Mar 68