GCH1 mutation and clinical study of Chinese patients with dopa‐responsive dystonia

Dopa‐responsive dystonia (DRD) is typically caused by heterozygous mutations in GTP cyclohydrolase 1 gene (GCH1). Our aim was to investigate the clinical and genetic features of Chinese DRD patients. We analyzed a cohort of Chinese DRD patients' clinical data. Mutation of the GCH1 gene was screened by direct sequencing. Additionally, multiplex ligation‐dependent probe amplification (MLPA) assay targeting the GCH1 and the TH gene to evaluate large exon deletion or duplicate mutation of the genes were performed in point mutation‐negative patients. Ten sporadic DRD patients and two pedigrees including six patients were included in the study. The onset age ranged from 3 to 15 years old. All patients initially presented with walking problems due to lower limb dystonia. The delay between onset and diagnosis ranged from 1 to 42 years old. The symptoms were completely or near‐completely abolished with low dose levodopa treatment (dosages ranged from 25 mg to 400 mg/day). Direct sequencing in 14 patients found two known mutations (Gly203Arg in exon 5 in four unrelated patients and Met102Lys in exon 1 in one patient) and one new mutation (Thr186Ile mutation in exon 5 in two unrelated pedigrees). A heterozygous exon 2 deletion in the GCH1 gene was found in one of three point mutation‐negative patients by MLPA analysis. Our clinical findings in DRD patients were consistent with other studies. GCH1 gene mutations were quite common in Chinese patients. MPLA should be performed in routine deletion analysis of GCH1 in point mutation‐negative DRD patients. © 2010 Movement Disorder Society     

A new mutation of GCH1 in triplets family with dopa‐responsive dystonia

Background: Dopa‐responsive dystonia (DRD) is associated with mutations of the GCH1. We first report four female siblings with DRD from one family, including three monozygotic triplets patients clinically and genetically. Methods: We performed GCH1 analysis by direct sequencing of PCR product amplified with primers designed to cover the entire exons of GCH1 in those four patients and their mother. Results: In all four patients with DRD, a new frameshift mutation (c.729delG; p.A190fsX191) was identified in the exon 5 of GCH1. Conclusions: The frameshift mutation results in truncated GCH1 protein which is suspected to result in loss of function of the catalytic GTP‐cyclohydrol domain.     

A novel missense mutation of the GTP cyclohydrolase I gene in a Korean family with hereditary progressive dystonia/dopa-responsive dystonia

Hereditary progressive dystonia with marked diurnal fluctuation/dopa-responsive dystonia (HPD/DRD) shows the considerable heterogeneity of clinical phenotypic expression and a dramatic sustained response to levodopa. The autosomal dominant HPD/DRD is caused by mutations in the gene coding GTP cyclohydrolase I (GCH I), the enzyme that catalyzes the first step in the biosynthesis of tetrahydrobiopterin. Previous studies suggested that normal [18F]Dopa positron emission tomography or [123I]beta-CIT single-photon emission computed tomography (SPECT) imaging, indicating intact structural integrity of nigrostriatal neurons, may be useful for differentiating HPD/DRD from clinically similar conditions such as juvenile Parkinson's disease with dystonia that have a considerably poorer prognosis. We here report a Korean family affected with HPD/DRD due to a novel missense mutation of the GCH I gene (T-->G mutation in exon 2), Met 137 Arg, which may change the conformation of the binding site of GCH I. The clinical features are considerably variable within the family. We documented normal striatal uptake of [123I]IPT, a dopamine transporter ligand with fast washout kinetics, in our patients by using SPECT. This method can be helpful in diagnosing HPD/DRD in uncertain cases.     

多巴反应性肌张力障碍患者的GCH1基因突变检测

目的分析多巴反应性肌张力障碍(dopa responsive dystonia,DRD)患者的GCH1基因突变。方法我们抽取21例来自医院门诊及住院的散发型多巴反应性肌张力障碍患者的肘静脉血,并提取外周血全基因组DNA。Primer3设计GCH1基因6个外显子的引物,PCR扩增GCH1基因的外显子及周边部分内含子序列,并对PCR产物进行测序。测序结果与正常序列进行比对,发现碱基变异后进行序列分析以确定是否多态。结果成功扩增21位DRD患者GCH1基因的6个外显子。经过分析,GCH1基因外显子序列未发现基因突变。仅在4个患者的1号外显子发现1个单核苷酸多态(SNP)c.68CT,该SNP没有产生氨基酸的改变。结论本地区多巴反应性肌张力障碍患者未发现GCH1基因突变,DRD患者可能存在其他致病基因。GCH1基因突变检测目前仍不能作为早期诊断的依据。     

Phenocopies in a large GCH1 mutation positive family with dopa responsive dystonia: confusing the picture?

BACKGROUND: Dopa responsive dystonia (DRD) is a disorder characterised by childhood onset dystonia but a wide range of clinical presentations has now been described. OBJECTIVE: To study a large Canadian family with presumed DRD. METHODS: The clinical features of the family were collected before molecular genetic mutational analysis. RESULTS: All nine individuals in whom a clinical diagnosis of DRD was definite or probable were heterozygous for a GCH1 gene deletion. However, eight of nine possibly clinically affected members did not carry the GCH1 mutation. CONCLUSIONS: Great care must be taken in diagnosing DRD even in families with the classic phenotype, because of potential phenocopies of the disease.     

Utility of MLPA in deletion analysis of <Emphasis Type="Italic">GCH1</Emphasis> in dopa-responsive dystonia

We applied multiple ligation-dependent probe amplification (MLPA) to patients from three families with characteristic dopa-responsive dystonia (DRD) but no base change in the gene GCH1. We found a complete deletion of GCH1 in affected members of family 1, and partial deletions in affected individuals of family 2 (exons 4-6) and of family 3 (exons 2-6). The findings were confirmed by quantitative real-time PCR. Our investigations demonstrate the utility of MLPA for routine deletion analysis of GCH1 in DRD patients with no sequence changes in this gene.     

Novel GCH1 mutation in a Brazilian family with dopa‐responsive dystonia

Dopa responsive Dystonia (DRD) was first described in 1971 and typically begins at childhood with gait dysfunction caused by foot dystonia progressing to affect other extremities. There is marked diurnal fluctuation and sustained improvement of symptoms with low dose levodopa therapy. Heterozygous mutation of the gene GCH1 has been shown to cause DRD. We studied GCH1 in nine patients with DRD from six families of Federal University of Minas Gerais Movement Disorders Clinic. We identified three mutations; two affected siblings carried a novel T209P mutation and two siblings from another family were compound heterozygous carriers of Met211Val and Lys224Arg mutations. To our knowledge this is the first report of GCH1 mutations underlying DRD in patients from Brazil. © 2007 Movement Disorder Society     

Dopa-responsive dystonia and Tourette syndrome in a large Danish family

BACKGROUND: Guanosine triphosphate cyclohydrolase I (GTPCH) catalyzes the first step in the synthesis of tetrahydrobiopterin (BH4). Autosomal dominantly inherited defects in the GTPCH gene (GCH1) cause a form of dystonia that is responsive to treatment with levodopa (dopa-responsive dystonia [DRD]). OBJECTIVE: To investigate molecular and clinical aspects of DRD in a large Danish family. METHODS: For analysis of the GCH1 gene, a mutation-scanning method based on denaturing gradient gel electrophoresis (DGGE) was used. A novel mutation, X251R, was identified in the GCH1 gene of 2 distantly related Danish patients with DRD, one of whom also had Tourette syndrome (TS). Thirty-five additional family members were investigated for this mutation, and 16 of them underwent clinical neurological examination. RESULTS: A total of 18 patients were heterozygous for the X251R allele, 16 of whom had neurological complaints spanning from very mild parkinsonism to severe invalidism due to dystonia. Of 13 symptomatic heterozygotes who had been neurologically examined, 10 had signs of dystonia or parkinsonism. Sixteen of the heterozygotes were treated with levodopa, and 13 reported a treatment benefit. Three of the symptomatic heterozygotes had signs of TS. CONCLUSIONS: This study confirms the large variability in DRD symptoms and emphasizes the usefulness of molecular analysis for diagnosis and treatment of DRD. The presence of TS is suggested to be coincidental, though the development of TS-like symptoms due to mutations in GCH1 cannot be excluded.     

Novel GCH-1 mutations and unusual long-lasting dyskinesias in Korean families with dopa-responsive dystonia

ObjectiveTo describe the long-term follow-up data of Korean patients with GTP cyclohydrolase (GTPCH) I deficient dopa-responsive dystonia (DRD) with novel mutations and unusual long-lasting dyskinesias.MethodsClinical features and genetic testing results of GCH1 from 19 patients that included 4 families who have been followed-up for up to 25 years were analyzed.ResultsGCH1 mutations were confirmed in all our symptomatic subjects including 3 novel point mutations. All the subjects except for one family had typical manifestations of autosomal dominant GTPCH-I deficient DRD including early childhood onset dystonia predominantly in the legs, marked diurnal variation, intact cognition, no other systemic symptoms, and excellent sustained response to levodopa. The one family who was the exception had two gene positive members of DRD and one with dopa-unresponsive cervical dystonia with negative GCH1 mutation. One family and a sporadic case had been reported as gene negative in a previous study, but they typically had preserved dopamine transporter binding and low neopterin levels in cerebrospinal fluids; thus, GCH-1 mutation had been highly suspected, which was now confirmed by repeating the genetic testing this time. An early childhood-onset patient developed choreiform dyskinesias right after administration of levodopa. The dyskinesia had lasted for more than 4 years regardless of the levodopa dosages and then subsided while maintaining levodopa.ConclusionThis report emphasizes the usefulness of the neopterin level in cerebrospinal fluids and dopamine transporter imaging in the differential diagnosis of DRD syndromes and a possible mechanism of levodopa-induced-dyskinesia in early childhood onset case.     

A novel missense mutation in GTP cyclohydrolase I (GCH1) gene causes dopa‐responsive dystonia in Chinese Han population

Background: Dopa‐responsive dystonia has been shown to be caused by a number of different mutations in the GCH1 gene. Up to now, only several genetic studies of Chinese patients with Dopa‐responsive dystonia (DRD) have been reported. Methods: We performed a genetic analysis by amplifying the entire coding region of GCH1 gene and direct sequencing in four DRD families from mainland China. Results: A novel missense mutation, Gly155Ser, has been identified in a sporadic case from a consanguineous marriage family. Furthermore, two known mutations, Met137Arg and Gly203Arg, have also been detected in the other families. Conclusions: A novel missense mutation in the GCH1 gene can be associated with DRD. Our findings further expanded the mutational spectrum of GCH1 gene associated with DRD.     

Dopa-responsive dystonia due to a large deletion in the GTP cyclohydrolase I gene

Although it is assumed that most patients with autosomal dominant dopa-responsive dystonia (DRD) have a GTP cyclohydrolase I dysfunction, conventional genomic DNA sequencing of the gene (GCH1) coding for this enzyme fails to reveal any mutations in about 40% of DRD patients, which makes molecular genetic diagnosis difficult. We found a large heterozygous GCH1 deletion, which cannot be detected by the usual genomic DNA sequence analysis, in a three-generation DRD family and conclude that a large genomic deletion in GCH1 may account for some "mutation-negative" patients with dominantly inherited DRD.     

Utility of MLPA in deletion analysis of GCH1 in dopa-responsive dystonia

We applied multiple ligation-dependent probe amplification (MLPA) to patients from three families with characteristic dopa-responsive dystonia (DRD) but no base change in the gene GCH1. We found a complete deletion of GCH1 in affected members of family 1, and partial deletions in affected individuals of family 2 (exons 4–6) and of family 3 (exons 2–6). The findings were confirmed by quantitative real-time PCR. Our investigations demonstrate the utility of MLPA for routine deletion analysis of GCH1 in DRD patients with no sequence changes in this gene.An erratum to this article can be found at     

Dopa-responsive dystonia: clinical, genetic, and biochemical studies]

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.     

Four novel mutations in the GCH1 gene of Chinese patients with dopa‐responsive dystonia

Mutation detection in the guanosine triphosphate cyclohydrolase I gene (GCH1) was performed from 4 female patients with dopa‐responsive dystonia (DRD). DNA sequencing revealed the presence of four novel mutations including c.2T>C(M1T), c.239G>A(S80N), c.245T>C(L82P), and IVS5+3 del AAGT. These four mutations were not found in 100 genetically unrelated healthy controls with the same ethnic background band. In all 3 childhood‐onset patients, DRD started in the legs, and missense mutations were located in the coding region of GCH1. Deletion mutation in the fifth exon–intron boundary of GCH1 was detected in the adult‐onset patient. Although the data presented here do not provide sufficient evidence to establish a genotype–phenotype correlation of DRD, it is important to know the clinic features and genetic defects of DRD patients, which will help prenatal diagnosis, early diagnosis, evaluate the prognosis, and facilitate causal therapy with levodopa. © 2010 Movement Disorder Society     

Novel non‐sense GCH1 mutation in a South African family diagnosed with dopa‐responsive dystonia

Background: Dopa‐responsive dystonia (DRD), a movement disorder characterized by onset in early childhood and a dramatic response to low doses of levodopa, has been shown to be caused by a number of different mutations in the GCH1 gene. Methods: We identified a South African family which presented with DRD in three family members. Polymerase chain reaction (PCR) primers were designed to span all six exons of GCH1 and the PCR products were screened for pathogenic mutations using direct sequencing. Results: A novel non‐sense mutation (c.233delT; p.I78fsX79) was identified in the DRD patients, which would produce a markedly truncated protein of only 78 amino acids. This mutation was also present in a number of asymptomatic family members. Conclusions: A novel non‐sense mutation in the GCH1 gene can be associated with DRD and reduced penetrance in South African patients.     

A novel tyrosine hydroxylase variant in a group of Chinese patients with dopa-responsive dystonia

Dopa-responsive dystonia (DRD) comprises a heterogeneous group of movement disorders. A limited number of studies of Chinese patients with DRD have been reported. In the present study, we investigated the clinical and genetic features of 12 Chinese DRD families. Point mutation analysis of the GTP-cyclohydrolase I (GCH1), tyrosine hydroxylase (TH) and sepiapterin reductase (SPR) genes was conducted by direct sequencing. In addition, multiplex ligation-dependent probe amplification targeting GCH1 and TH was performed in “mutation-free” patients. Three reported mutations (IVS2-2A>G, c.293C>T, c.550C>T) were detected in GCH1, whereas two compound heterozygous variants were identified in TH, one of which was novel (c.1083C>A). Furthermore, this novel variant was not detected in any of the 250 ethnicity-matched, healthy controls. No exon deletions or duplicate mutations in the two genes were found in patients with DRD. No mutation in SPR was found. In addition, one patient with the IVS2-2A>G mutation in GCH1 showed signs of Parkinsonism. In conclusion, we here identified a novel heterozygous variant in TH (c.1083C>A). It is important to perform routine screening of GCH1 and TH for patients with DRD. While for patients with Parkinsonism, GCH1 mutation analysis should be performed after screening of genes like PARKIN, PARK7 (DJ-1) and PINK1.     

Dopa-responsive dystonia]

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.     

Dopa-responsive dystonia: A clinical and molecular genetic study

We have studied the GTP-cyclohydrolase 1 (GCH-1) gene in 30 patients with the diagnosis of clinically definite (n = 20) or possible (n = 10) dopa-responsive dystonia (DRD) as well as in a child with atypical phenylketonuria due to complete GCH-1 deficiency. A large number of new heterozygote mutations (seven point mutations, two splice site mutations and one deletion) as well as a new homozygote mutations in the child with atypical phenylketonuria were detecte. In addition, two previously described mutations wer found in two other cases. We further extended our investigation of GCH-1 to the 5′ and 3′ regulatory regions and report the first detection of point mutations in the 5′ untranslated region. Demethylation of CpG islands does not appear to be an important causative factor for the GCH-1 mutations in DRD. In addition, we have extended the clinical phenotype of genetically proven DRD to focal dystonia, dystonia with relapsing and remitting course, and DRD with onset in the first week of life. None of our DRD patients without a mutation in GCH-1 had the 3-bp deletion recently detected in DYT1, the causative gene for idiopathic torsion dystonia with linkage to 9q34.     

Striatal biopterin and tyrosine hydroxylase protein reduction in dopa-responsive dystonia.

OBJECTIVE: To determine the mechanism leading to striatal dopamine (DA) loss in dopa-responsive dystonia (DRD). BACKGROUND: Although mutations in the gene GCH1, coding for the tetrahydrobiopterin (BH4) biosynthetic enzyme guanosine triphosphate-cyclohydrolase I, have been identified in some patients with DRD, the actual status of brain BH4 (the cofactor for tyrosine hydroxylase [TH]) is unknown. METHODS: The authors sequenced GCH1 and measured levels of total biopterin (BP) and total neopterin (NP), TH, and dopa decarboxylase (DDC) proteins, and the DA and vesicular monoamine transporters (DAT, VMAT2) in autopsied brain of two patients with typical DRD. RESULTS: Patient 1 had two GCH1 mutations but Patient 2 had no mutation in the coding region of this gene. Striatal BP levels were markedly reduced (<20% of control subjects) in both patients and were also low in two conditions characterized by degeneration of nigrostriatal DA neurons (PD and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treated primate), whereas brain NP concentrations were selectively decreased (<45%) in the DRD patients. In the putamen, both DRD patients had severely reduced (<3%) TH protein levels but had normal concentrations of DDC protein, DAT, and VMAT2. CONCLUSIONS: The data suggest that 1) brain BH4 is decreased substantially in dopa-responsive dystonia, 2) dopa-responsive dystonia can be distinguished from degenerative nigrostriatal dopamine deficiency disorders by the presence of reduced brain neopterin, and 3) the striatal dopamine reduction in dopa-responsive dystonia is caused by decreased TH activity due to low cofactor concentration and to actual loss of TH protein. This reduction of TH protein, which might be explained by reduced enzyme stability/expression consequent to congenital BH4 deficiency, can be expected to limit the efficacy of acute BH4 administration on dopamine biosynthesis in dopa-responsive dystonia.     

A case of late-onset Segawa syndrome (autosomal dominant dopa-responsive dystonia) with a novel mutation of the GTP-cyclohydrase I (GCH1) gene

We report a case of a 46-year-old Japanese woman with hereditary progressive dystonia with marked diurnal fluctuations and dopa-responsive dystonia (HPD/DRD). She developed difficulty in walking at the age of 44 years due to bradykinesia as well as hand tremors, muscle rigidity, increased tendon reflexes and mild dystonia in the lower extremities, all of which responded remarkably to low doses of levodopa (150 mg/day). Biopterin and neopterin concentrations in the cerebrospinal fluid (CSF) were decreased. Analysis of the guanosine 5′-triphosphate cyclohydrolase I (GCH1) gene revealed a novel mutation (W53X) in one allele. The GCH1 activity that was expressed in mononuclear blood cells was almost half the normal value (usually 2–20% of the normal value (39.0 ± 9.2 pmol/ml) in patients with HPD/DRD). The relatively conserved GCH1 activity that is expressed in stimulated peripheral blood mononuclear cells may be related to the late clinical symptoms in this patient.