Phenotypical variability and atypical presentations in a French cohort of Andersen-Tawil syndrome.
Eur J Neurol
; 29(8): 2398-2411, 2022 08.
Article
em En
| MEDLINE
| ID: mdl-35460302
ABSTRACT
BACKGROUND AND PURPOSE:
Andersen-Tawil syndrome (ATS) is a skeletal muscle channelopathy caused by KCNJ2 mutations, characterized by a clinical triad of periodic paralysis, cardiac arrhythmias and dysmorphism. The muscle phenotype, particularly the atypical forms with prominent permanent weakness or predominantly painful symptoms, remains incompletely characterized.METHODS:
A retrospective clinical, histological, electroneuromyography (ENMG) and genetic analysis of molecularly confirmed ATS patients, diagnosed and followed up at neuromuscular reference centers in France, was conducted.RESULTS:
Thirty-five patients from 27 unrelated families carrying 17 different missense KCNJ2 mutations (four novel mutations) and a heterozygous KCNJ2 duplication are reported. The typical triad was observed in 42.9% of patients. Cardiac abnormalities were observed in 65.7% 56.5% asymptomatic and 39.1% requiring antiarrhythmic drugs. 71.4% of patients exhibited dysmorphic features. Muscle symptoms were reported in 85.7%, amongst whom 13.3% had no cardiopathy and 33.3% no dysmorphic features. Periodic paralysis was present in 80% and was significantly more frequent in men. Common triggers were exercise, immobility and carbohydrate-rich diet. Ictal serum potassium concentrations were low in 53.6%. Of the 35 patients, 45.7% had permanent weakness affecting proximal muscles, which was mild and stable or slowly progressive over several decades. Four patients presented with exercise-induced pain and myalgia attacks. Diagnostic delay was 14.4 ± 9.5 years. ENMG long-exercise test performed in 25 patients (71.4%) showed in all a decremental response up to 40%. Muscle biopsy performed in 12 patients revealed tubular aggregates in six patients (associated in two of them with vacuolar lesions), dystrophic features in one patient and non-specific myopathic features in one patient; it was normal in four patients.DISCUSSION:
Recognition of atypical features (exercise-induced pain or myalgia and permanent weakness) along with any of the elements of the triad should arouse suspicion. The ENMG long-exercise test has a high diagnostic yield and should be performed. Early diagnosis is of utmost importance to improve disease prognosis.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Síndrome de Andersen
Tipo de estudo:
Diagnostic_studies
/
Observational_studies
/
Prognostic_studies
/
Risk_factors_studies
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Screening_studies
Limite:
Humans
Idioma:
En
Revista:
Eur J Neurol
Assunto da revista:
NEUROLOGIA
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
França