Congenital myasthenic syndromes: achievements and limitations of phenotype-guided gene-after-gene sequencing in diagnostic practice: a study of 680 patients.
Congenital myasthenic syndromes (CMSs) are clinically and genetically heterogeneous disorders characterized by a neuromuscular transmission defect. Even though CMSs are genetic disorders, they are highly treatable, and the appropriate drug treatment depends on the underlying genetic defect. This highlights the importance of genetic testing in CMS. In recent years, the molecular basis of CMS has constantly broadened and disease-associated mutations have been identified in 14 genes encoding proteins of the neuromuscular junction. In the dawn of novel sequencing strategies, we report on our 14-year experience in traditional Sanger-based mutation screening of a large cohort of 680 independent patients with suspected CMS. In total, we identified disease-causing mutations in 299 patients (44%) of patients in various known CMS genes, confirming the high degree of genetic heterogeneity associated with the disease. Apart from four known founder mutations, and a few additional recurrent mutations, the majority of variants are private, found in single families. The impact of previously reported genotype-phenotype correlations on efficiency of genetic testing was analyzed in our population. Taking our experiment into account, we present our algorithm for genetic testing in CMS.
Friedrich-Baur-Institut, Ludwig Maximilians University, Munich, Germany. angela.abicht@med.unimuenchen.de
Angela
A
Abicht
Marina
M
Dusl
Constanze
C
Gallenmüller
Velina
V
Guergueltcheva
Ulrike
U
Schara
Adele
A
Della Marina
Eva
E
Wibbeler
Sybille
S
Almaras
Violeta
V
Mihaylova
Maja
M
von der Hagen
Angela
A
Huebner
Amina
A
Chaouch
Juliane S
JS
Müller
Hanns
H
Lochmüller
D015331:Cohort Studies; D005260:Female; D056726:Genetic Association Studies; D018740:Genetic Heterogeneity; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D009154:Mutation; D020294:Myasthenic Syndromes, Congenital / Q000175:diagnosis* / Q000235:genetics*; D011950:Receptors, Cholinergic / Q000235:genetics / Q000378:metabolism
D011950:Receptors, Cholinergic