Research Article: A Pediatric Case of COLQ-Related Congenital Myasthenic Syndrome with Marked Fatigue
Abstract:
Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous inherited disorder that is treatable. Although the disease usually develops at birth or during infancy, some patients develop the disease in the second to third decades of life. Collagen-like tail subunit of asymmetric acetylcholinesterase (COLQ)-related CMS is CMS with mutations in the COLQ, which results in end-plate acetylcholinesterase deficiency. Diagnostic delay is common in patients with later-onset CMS due to slow progression and fluctuating symptoms. Understanding CMS with atypical and unusual presentations is important to treat this condition effectively. Here, we report a case of COLQ-related CMS. A 10-year-old girl presented with only marked fatigue, which was provoked by exercise but improved after 30–60 min of rest. While motor nerve conduction velocity was normal, a compound muscle action potential (CMAP) with four peaks was recorded. Repetitive stimulation of the accessory nerve exhibited a decrease in CMAP amplitude. Genetic tests revealed compound heterozygous mutations in COLQ (c.1196-1_1197delinsTG and c.1354C>T). Treatment with salbutamol improved fatigue but not the electrophysiological markers. Thus, significant fatigue is a hallmark of COLQ-related CMS; early diagnosis is essential for ensuring appropriate treatment.
Introduction:
Congenital myasthenic syndromes (CMS) are rare genetic disorders comprising a subset of neuromuscular disorders in which genetic defects result in the dysfunction of proteins comprising the neuromuscular junction (NMJ) [1]. Collectively, these proteins participate in the structure, function, and repair of the NMJ [1]. As a clinically and genetically heterogeneous set of diseases [1], the clinical spectrum of CMS is highly variable, ranging from minor symptoms to progressive disabling weakness [2]. In some subtypes…
Read more