1. 511P Blood biomarkers in a cohort of patients with CHRNE-associated congenital myasthenic syndrome.
- Author
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Della Marina, A., Koutsoulidou, A., Natera de Benito, D., Tykocinski, L., Tomazou, M., Georgiou, K., Kölbel, H., Nascimento, A., Ortez, C., Lochmüller, H., Phylactou, L., Ruck, T., Abicht, A., Schara-Schmidt, U., Kale, D., Hentschel, A., and Roos, A.
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CONGENITAL myasthenic syndromes , *METABOLOMIC fingerprinting , *LEUCOCYTES , *BLOOD proteins , *SECRETORY granules - Abstract
Pathogenic variants in CHRNE encoding the epsilon subunit of acetyl choline receptor (AChR) result in impaired neuromuscular transmission and congenital myasthenic syndromes (CMS). Clinical manifestations include facial, ocular and limb fatigability and weakness, whereby severity of symptoms may vary in patients harboring the same pathogenic variant. Although the underlying pathophysiology is well-known, blood biomarkers enabling a patient-stratification are lacking. Previous studies revealed CHRNE protein in white blood cells (WBC) rendering these cells suitable for the study of cellular and minimal-invasive marker proteins. This retrospective two center-study includes 19 patients carrying biallelic pathogenic variants in CHRNE identified by molecular genetic testing. The patients were clinically characterized according to clinical severity (grade 1-4). Biomarker discovery was carried out on blood samples: proteomic profiling was performed on WBC (n =12) and on extracellular vesicles (EVs) purified from serum samples (n =7) in addition to amino acid profiling (n = 9) and miRNA screening (n = 18) on sera. In 19 patients (mean age 14.8 years) from 13 families seven known pathogenic variants in CHRNE were identified in addition to one variant previously not reported (c.1032+2_1032+3delTAinsGT). Whereas 15 patients were classified as mildly affected (group A: grade 1 and 2), 4 patients were classified as moderate or severely affected (group B: grade 3 and 4). Proteomics unveiled a significant increase of 7 and a decrease of 36 proteins in WBC in comparison to normal, age matched controls. GO-term based in silico studies of these dysregulated proteins indicated affection of secretory granules and the extracellular space. When comparing proteomic signatures of CHRNE-patients with a mild (A) versus moderate to severe phenotypes (B), 2 proteins (SCAMP2 and SNX2) were significantly increased in second group (B). These two proteins are involved in vesical transport. Prompted by this finding, proteomic profiling of EVs was initiated revealing a significant dysregulation of 20 proteins (7 are increased and 13 decreased). Three of these proteins (TARSH, ATRN & PLEC) are known to be important for synaptogenesis and synaptic function. Metabolic profiling of sera showed a decrease of 7 amino acids/ amino acid metabolites (aspartic and glutamic acids, phosphoserine, amino adipate, citrulline, ornithine & 1-methyhistidine) in terms of a metabolic fingerprint in CHRNE-related CMS patients. Moreover, miRNA screening unveiled increase of miR−365b−3p and miR−483−3p and decrease of miR-4433b-3p when comparing sera of CHRNE patients versus healthy controls. Moreover, a comparison of CHRNE patients versus other CMS-subtypes showed increase of miR−205−5p, miR−10b−5p, and miR−483−5 and decrease of miR−1290. Our combined data introduce a panel of minimal-invasive biomarkers on protein, metabolic and miRNA level with some of those play different roles along the neuromuscular axis. In the latter regard, impaired EV homeostasis impacting on synaptic function seems to be a molecular disease driver and two proteins in WBC correlate with disease severity. Our miRNA profiles introduce four miRNAs which may open new avenues in CMS patient stratification. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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