ABSTRACT
RESUMEN Las distonías que responden a levodopa (DRD, siglas en inglés) abarcan un grupo de distonías primarias, causadas por deficiencias enzimáticas en la vía metabólica de las aminas y, por definición, comparten como característica principal su respuesta favorable y sostenida a levodopa. Existen hasta seis genes asociados a DRD, siendo el gen GCH1 el más frecuentemente involucrado. La presentación típica de esta entidad se caracteriza por su aparición en la niñez, distonía de inicio en miembros inferiores con fluctuación diurna, leve parkinsonismo y respuesta clara a dosis bajas de levodopa. Se incluye una búsqueda sistemática de la literatura con casos de DRD publicados en Latinoamérica.
SUMMARY Dopa-responsive dystonia (DRD) encompasses a heterogenous group of primary dystonias, caused by enzymatic deficiencies across the amines pathway and, by definition, show as their main characteristic a favorable and sustained response to levodopa. There are up to 6 genes associated with DRD, including pathogenic variants of the GCH1 gene as the most frequently involved. The typical presentation of DRD is characterized by start in childhood, lower limb-onset dystonia with daytime fluctuation, mild parkinsonism, and a sustained response to low doses of levodopa. A systematic literature search on DRD reported cases in Latin America is presented.
ABSTRACT
Objective:To explore the clinical characteristics of children with tyrosine hydroxylase deficiency (THD) in order to recognize this disease early as to optimize the treatment to improve the prognosis.Methods:A retrospective analysis was done on the clinical data of nine children with THD who were diagnosed at the Children′s Hospital of Fudan University from May 2018 to May 2020, including name, gender, age, age of onset, age of presentation, age of diagnosis, clinical manifestations, head imaging, tyrosine hydroxylase gene mutation, treatment, follow-up, and other results, which were classified according to Willemsen′s method, and the clinical characteristics were summarized and a literature review was carried out.Results:There were five males and four females with the age at onset ranged from newborn to two years and six months (median three months). The duration of diagnosis ranged from four months to five years and seven months (median nine months). The presenting symptom was motor retardation in seven cases. Clinical symptoms included hypokinesia in eight cases, limb dystonia in five cases, truncal hypotonia in four cases, dysphagia/dysarthria in four cases, oculogyric crises in four cases, tremor in three cases, rigidity in three cases, mask faces in three cases, bilateral ptosis in two cases, hypersalivation/sweating in two cases, diurnal fluctuation in two cases, myoclonic jerks in one case, and status dystonicus in one case. Cranial magnetic resonance imaging was normal in seven cases and non-specific in two cases (backward myelination in one case and bilateral ventricle enlargement and decreased white matter in another one). Eight tyrosine hydroxylase gene variants were found, including four missense variants, two frameshift variants, one shear variants and one nonsense variant, as well as three novel variants [c.1505_1518dup (p.R507Afs *23), c.1128_1138del (p.Q377Gfs *12), c.1058A>G(p.H353R)]. All patients were treated with levodopa and benserazide hydrochloride tables. The initial and maintenance doses of type A were 1.7-8.3 mg·kg -1·d -1 and 4.5-20.0 mg·kg -1·d -1, respectively. The initial and maintenance doses of type B were 1.7-12.5 mg·kg -1·d -1 and 4.6-12.0 mg·kg -1·d -1, respectively. In type A, four patients had dyskinesis which was relieved by decreasing the dose or maintaining the same dose of levodopa. One case of type B had dyskinesis which was self-resolving. Conclusions:Although the clinical manifestations of this disease are varied, the initial symptoms in children with onset within the first year of life are mostly hypokinesia, truncal hypotonia, and dystonia in limbs. It is recommended that children with THD, regardless of clinical type, should start at the minimum dose for easy segmentation in the range of 1.0-5.0 mg·kg -1·d -1, and the maintenance dose can be adjusted according to the individual response of the child. The incidence of dyskinesia of this disease is not low, but most can be treated by decreasing the initial dose and delaying the dosage rate.
ABSTRACT
Objective To explore the clinical characteristics,gene mutations,diagnosis and treatment of chil-dren with dopa-responsive dystonia due to tyrosine hydroxylase(TH)deficiency.Methods Five patients(3 boys and 2 girls)with dopa-responsive dystonia due to TH deficiency were diagnosed and followed up from January 2002 to October 2017.The clinical manifestations,laboratory findings,treatment and TH gene mutations associated with TH defi-ciency were analyzed.Results Five patients came from different families.They had the onset at the age of 8 months to 20 months with dystonia,paroxysmal muscular hypertonia and normal intelligence or mild mental retardation.All of them had been misdiagnosed as cerebral palsy.Two cases with floppy limbs presented with fatigue and tremor.One case with floppy limbs presented with seizures. Complex heterozygous mutations were found in TH gene of all patients,which helped to confirm the diagnosis.Eight mutations were identified in TH gene.Six of them were reported.Two novel muta-tions,c.1077C>A(p.C359X)and c.1228C>T(p.R410C)were detected.After the treatment by levodopa[2.2-5.4 mg/(kg·d)],significant improvement was observed.Three patients recovered their intellectual and motor activi-ties.Two patients were dramatically improved but with slightly uncoordinated movements.Conclusion The patients of dopa-responsive dystonia due to TH deficiency usually have the onset around one year of age with almost normal inte-lligence,motor retardation and dystonia.The patients are likely misdiagnosed as cerebral palsy.The treatment with levo-dopa can dramatically improve the symptoms.The etiological diagnosis is very important.