An unusual presentation of congenital myasthenic syndrome

Clinicians in Hong Kong report an unusual case of congenital myasthenic syndrome (CMS) that initially suggested an eating disorder:

• the patient was 42 years old at the time of diagnosis with CMS (slow-channel type),
• the clinical picture included very significant progressive weight loss (down to 34 kg with a body mass index of 13.8) and had been attributed to anorexia nervosa for over ten years,
• yet there was no voluntary fasting, no desired weight loss, nor amenorrhoea to support this diagnosis,
• the findings from the clinical history (fatigue dating back to the age of ten) combined with those from the EMGTracé rendant compte de l’activité électrique produite par la contraction musculaire, enregistré à l’aide d’une aiguille fine implantée dans le muscle. Il permet de savoir si le problème musculaire est dû à une atteinte des muscles ou à une atteinte des nerfs. (presence of a repetitive CMAP response) and genetic testing (positive family history, pathogenic variant in the CHRNA1 gene) enabled the diagnosis to be corrected and appropriate treatment with fluoxetine to be initiated.

Slow-Channel Congenital Myasthenic Syndrome due to a CHRNA1 Variant Masquerading as Atypical Anorexia Nervosa: A Case Report. Yeung TMH, Gao Y, So CF, Ling TK, Lam CW. Cureus. 2025 Nov