Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0013421 (dystonia)
8,418 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors present four cases from two unrelated families with young-onset predominant cervical dystonia with a dramatic sustained response to levodopa. Onset age was 12 years (range 9 to 15). Additional symptoms included postural hand tremor and laryngeal dystonia. Genetic testing for GTP cyclohydrolase I, tyrosine hydroxylase, and sepiapterin reductase was negative. These cases may represent new forms of dopa-responsive dystonia. Levodopa is advisable in all patients with young-onset cervical dystonia.
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PMID:Familial dopa-responsive cervical dystonia. 1650 23

Dopa-responsive dystonia (DRD) is a clinical syndrome characterized by childhood-onset dystonia and a dramatic and sustained response to low doses of levodopa. There are at least three causative genes for DRD: (1) the GCH1 gene on chromosome 14q22.1-q22.2, which encodes GTP cyclohydrolase I (GTPCH), the first enzyme in the biosynthetic pathway for tetrahydrobiopterin (BH4; the essential cofactor for tyrosine hydroxylase [THI]), (2) the TH gene on 11 p15.5, coding for the enzyme TH that catalyzes the rate-limiting step in the catecholamine biosynthesis, and (3) an as yet undefined gene on 14q13 (DYT14). In reports on DRD, in which conventional genomic DNA sequencing of GCH1 was conducted in a relatively large number of pedigrees, mutations in the coding region (including the splice sites) of this gene were found in approximately 60% (range: 49-79%) of DRD families. In our series, after conducting additional GCH1 testing (Southern blotting, cDNA sequencing, etc.) and TH analysis, 86% of families with DRD or dystonia with motor delay (an intermediate phenotype between GTPCH-deficient DRD [mild] and GTPCH-deficient hyperphenylalaninemia [severe]) had identifiable GCH1 or (rarely) TH mutations. Up to the present, only one pedigree with autosomal dominant DRD linked to the DYT14 locus has been reported. Neuropathological findings (no Lewy bodies and a normal population of cells with reduced melanin in the substantia nigra) in DRD patients with GTPCH dysfunction were similar to those in a patient with DYT14 dystonia. There have been no reports of autopsied patients with TH-deficient DRD. Neurochemical data suggest that striatal dopamine reduction in GTPCH-deficient DRD is caused not only by decreased TH activity resulting from a low cofactor (BH4) level but also by actual loss of TH protein without nerve terminal loss. This TH protein reduction in the striatum, especially in the putamen, may be due to a diminished regulatory effect of BH4 on stability (rather than expression) of TH molecules or to a dysfunction of TH protein transport from the substantia nigra to the striatum. The extent of striatal TH protein loss may be critical in determining DRD symptomatology and could contribute to gender-related incomplete penetrance of GCH1 mutations in GTPCH-deficient DRD families. Notwithstanding the discovery of the three causative loci for DRD, a therapeutic trial with low doses of levodopa is still the most practical approach to the diagnosis of this treatable disorder. The trial should be considered in all children with dystonic and/or parkinsonian symptoms or with unexplained gait disorders. Analyses of total biopterin and neopterin as well as neurotransmitter metabolites in CSF appear to be useful for the diagnosis of GTPCH-deficient DRD (the major form of DRD) and of TH-deficient DRD (the mild form of TH deficiency). Findings of the precise mechanism of striatal TH protein loss in GTPCH-deficient DRD, the actual status of dopaminergic systems in TH-deficient DRD, and the novel causative gene on the DYT14 locus will better define the pathogenesis of DRD.
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PMID:[Dopa-responsive dystonia: clinical, genetic, and biochemical studies]. 1654 91

Tetrahydrobiopterin (BH(4)) deficiencies are a highly heterogeneous group of disorders with several hundred patients, and so far a total of 193 different mutant alleles or molecular lesions identified in the GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS), sepiapterin reductase (SR), carbinolamine-4a-dehydratase (PCD), or dihydropteridine reductase (DHPR) genes. The spectrum of mutations causing a reduction in one of the three biosynthetic (GTPCH, PTPS, and SR) or the two regenerating enzymes (PCD and DHPR) is tabulated and reviewed. Furthermore, current genomic variations or SNPs are also compiled. Mutations in GCH1 are scattered over the entire gene, and only 5 out of 104 mutant alleles, present in a homozygous state, are reported to cause the autosomal recessive form of inheritable hyperphenylalaninemia (HPA) associated with monoamine neurotransmitter deficiency. Almost all other 99 different mutant alleles in GCH1 are observed together with a wild-type allele and cause Dopa-responsive dystonia (DRD, Segawa disease) in a dominant fashion with reduced penetrance. Compound heterozygous or homozygous mutations are spread over the entire genes for PTS with 44 mutant alleles, for PCBD with nine mutant alleles, and for QDPR with 29 mutant alleles. These mutations cause an autosomal recessive inherited form of HPA, mostly accompanied by a deficiency of the neurotransmitters dopamine and serotonin. Lack of sepiapterin reductase activity, an autosomal recessive variant of BH(4) deficiency presenting without HPA, was diagnosed in patients with seven different mutant alleles in the SPR gene in exons 2 or 3 or in intron 2. Details on all mutations presented here are constantly updated in the BIOMDB database (www.bh4.org).
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PMID:Mutations in the BH4-metabolizing genes GTP cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase, sepiapterin reductase, carbinolamine-4a-dehydratase, and dihydropteridine reductase. 1691 93

Dopa-responsive dystonia (DRD) is a clinical syndrome characterized by childhood-onset dystonia and a dramatic and sustained response to relatively low doses of levodopa. There are at least three causative genes for DRD: 1) the GCH1 gene on chromosome 14q22.1-q22.2, coding for the enzyme GTP cyclohydrolase I (GTPCH) that catalyzes the rate-limiting step in the tetrahydrobiopterin (BH4; the cofactor for tyrosine hydroxylase [TH]) biosynthesis, 2) the TH gene on 11p15.5, and 3) an as yet undefined gene on 14q13 (DYT14). In our series, 86% of families with DRD or dystonia with motor delay (an intermediate phenotype between GTPCH-deficient DRD [mild] and GTPCH-deficient hyperphenylalaninemia [severe]) had identifiable GCH1 or (rarely) TH mutations. Neurochemical data suggest that striatal dopamine reduction in GTPCH-deficient DRD (the major form of DRD) is caused not only by decreased TH activity resulting from a low cofactor level but also by actual loss of TH protein without nerve terminal loss. This TH protein reduction in the striatum (especially in the putamen) may be due to a diminished regulatory effect of BH4 on stability of TH molecules or to a dysfunction of TH protein transport from the substantia nigra to the striatum.
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PMID:[Dopa-responsive dystonia]. 1743 76

Segawa disease was first reported in 1971 as 'Hereditary progressive basal ganglia disease with marked diurnal fluctuation'. In 1976, after experience of a 51 year old patient with 43 years non-treatment periods, I confirmed this disease as dystonia. Polysomnographies revealed selective involvement of the dopamine (DA) neuron without involvement of the D2 receptors. These were confirmed by PET studies performed early 90's. The clinical course of this adult patient was correlated to the age variation of the activities of tyrosine hydroxylase (TH) in the striatum and suggested non-progressive decrease of TH at the terminal of the nigrostriatal DA neuron. Histochemical studies confirmed selective involvement of the D1-direct pathways without any pathological changes. In 1990, Fujita and Shintaku suggested the deficiency of the GTP cyclohydrolase I (GCH-I) as the cause of this disease. In 1993, Ichinose and his colleagues clarified the gene of GCH-I as the causative gene. After the discovery of the gene, it is realized that Segawa disease has two clinical types, postural dystonia and action dystonia. The latter with involvement of the DA neuron innervating to the subthalamic nucleus with D1 receptor has focal or segmental dystonia or adult onset cases and provides phenotypical variation.
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PMID:[Japanese originality, clinical symptoms to the causative gene 1 Segawa disease]. 1821 Jul 86

The first report of Segawa disease was a report of two girls, cousin each other, with dystonic posture, under the title of "Hereditary progressive basal ganglia disorder" in 1971. After accumulation of cases with an adult case, I confirmed this disease does not transform to Parkinson's disease in adulthood and published with a nomenclature of "Hereditary progressive dystonia with marked diurnal fluctuation" in 1976. Polysomnographical examination for evaluating the sleep effects and correlation of the natural course to the age variation of the tyrosine hydroxylase activities in the striatum, these speculated this is a particular disorder caused by non-progressive decrement of the tyrosine hydroxylase at the terminal of the nigrostriatal dopamine neuron. This was supported by PET studies in early 1990's. Evaluation of pteridine metabolites in cerebrospinal fluid revealed partial decrement of the GTP cyclohydrolase I as the cause of this disease and induced the discovery of the causative gene. After the discovery of the gene, an autopsied case with dopa-responsive dystonia was confirmed as Segawa disease and the neuropathological and histochemical findings confirmed the hypothesis. Furthermore, these showed rather selective involvement the D1-direct pathways in the disease. However, it was also clarified existence of two types, one, classic type, postural dystonia and the other action dystonia with vigorous dystonic movements besides dystonic posture, which, is postulated to be caused by the dopamine neuron innervating to the subthalamic nucleus with D1 neuron. Existence of these two phenotypes also provides phenotypical variation of Segawa disease.
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PMID:[Segawa disease]. 1823 27

We describe a unique presentation of autosomal recessive (AR) GTP cyclohydrolase I (GTPCH) deficiency, with severe CNS involvement but without hyperphenylalaninemia. A male infant presented with progressive spasticity, dystonia and oculogyric episodes. Blood phenylalanine levels were persistently normal: whereas an oral phenylalanine loading test revealed impaired phenylalanine clearance. CSF neopterin and tetrahydrobiopterin (BH(4)) were low, homovanillic acid marginally low and 5-hydroxyindoleacetic acid normal. Fibroblasts showed decreased GTPCH enzyme activity. A homozygous novel mutation of GCH1, p.V206A, was identified. On treatment (BH(4), L-Dopa/Carbidopa and 5-hydroxytryptophan), motor development improved. Mutational analysis provided neonatal diagnosis of a younger brother who, after 18 months on treatment, shows normal development. AR GTPCH I deficiency can present without hyperphenylalaninemia and with normal or subtle CSF neurotransmitter profiles. Testing for GTPCH deficiency should be considered for patients with unexplained neurological symptoms and extrapyramidal movement disorder.
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PMID:Autosomal recessive GTP cyclohydrolase I deficiency without hyperphenylalaninemia: evidence of a phenotypic continuum between dominant and recessive forms. 1827 79

Tetrahydrobiopterin (BH4) deficiencies are disorders affecting phenylalanine metabolism in the liver and neurotransmitter biosynthesis in the brain. BH4 is the essential cofactor in the enzymatic hydroxylation of 3 aromatic amino acids (phenylalanine, tyrosine, and tryptophan). BH4 is synthesized from guanosine triphosphate (GTP), catalyzed by GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydropterin synthase, and sepiapterin reductase (SR), and in aromatic amino acids, the hydoxylating system is regenerated by pterin-4a-carbinolamine dehydrolase and dihydropteridine reductase (DHPR). BH4 deficiency has been diagnosed in patients with hyperphenylalaninemia (HPA) by neonatal mass-screening based on BH4 oral-loading tests, analysis of urinary or serum pteridines, and measurement of DHPR activity in blood using a Guthrie card. BH4 deficiency without treatment causes combined symptoms of HPA and neurotransmitter (dopamine, norepinephrine, epinephrine, and serotonin) deficiency, such as red hair, psychomotor retardation, and progressive neurological deterioration. However, autosomal dominant GTPCH deficiency and autosomal recessive SR deficiency leads to BH4 and neurotransmitter deficiency without HPA and may not be detected by neonatal screening for phenylketonuria. The former is Segawa's disease, which is characterized by dopa-responsive dystonia with marked diurnal fluctuation and is caused by a defect of GTPCH, and the latter is SR deficiency, which is characterized by progressive psychomotor retardation, dystonia, and severe dopamine and serotonin deficiencies. Biochemical diagnosis is performed by the measurement of neopterin and biopterin levels, since both are low in Segawa disease, and the biopterin level is high in SR deficiency in cerebrospinal fluid. We must consider metabolic disorders of biopterin in child neurologic diseases with dystonia.
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PMID:[Biopterin and child neurologic disease]. 1917 9

Autosomal dominant GTP cyclohydrolase I (AD GCH 1) deficiency (Segawa disease) is an autosomal dominant dopa responsive dystonia caused by heterozygous mutation of the GCH 1 gene located on 14q22.1-q22.2. Although a number of mutations have been reported, the change remains highly stable within families, and causes a decrease in the tyrosine hydroxylase protein at the nigrostriatal (NS)-dopamine (DA) neuron terminal. In addition, decreased tetrahydrobiopterin levels early in the development affect DA receptors age-dependently, and produce a spectrum of specific symptoms attributed to neuronal changes traced to processes in the development of the NS-DA neuron, related striatal projection neurons, and the output projection of the basal ganglia.
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PMID:Autosomal dominant GTP cyclohydrolase I (AD GCH 1) deficiency (Segawa disease, dystonia 5; DYT 5). 1929 34

In a recent GCH1 mutation screen, an 18-bp deletion was identified within the proximal promoter in two patients with early-onset Parkinson's disease. The mutation removes cAMP response element critical for adequate GTP cyclohydrolase I activity in selected cell types, including dopaminergic neurons, but its biological significance was unclear as it was also detected in one control individual. We present an 11-year-old boy with infantile-onset severe dystonic encephalopathy without hyperphenylalaninemia whom we found compound heterozygous for the same promoter GCH1 deletion and another common missense mutation associated with classical dopa-responsive dystonia. Extensive diagnostic work up excluded other causes of dystonia, and comprehensive mutation scan did not reveal any additional GCH1 sequence variations, supporting the association between the promoter deletion and disease phenotype.
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PMID:Severe dystonic encephalopathy without hyperphenylalaninemia associated with an 18-bp deletion within the proximal GCH1 promoter. 2084 87


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