251. Recessive VAMP1 mutations associated with severe congenital myasthenic syndromes - A recognizable clinical phenotype.
- Author
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Polavarapu K, Vengalil S, Preethish-Kumar V, Arunachal G, Nashi S, Mohan D, Chawla T, Bardhan M, Nandeesh B, Gupta P, Gowda VK, Lochmüller H, and Nalini A
- Subjects
- Adolescent, Child, Child, Preschool, Consanguinity, Female, Homozygote, Humans, India, Infant, Mutation, Myasthenic Syndromes, Congenital diagnosis, Pedigree, Phenotype, Myasthenic Syndromes, Congenital genetics, Vesicle-Associated Membrane Protein 1 genetics
- Abstract
Three unrelated girls, all born to consanguineous parents had respiratory distress, severe hypotonia at birth along with prominent fatigable muscle weakness and characteristic myopathic facies. In addition, patient 1 had fatigable ptosis, ophthalmoparesis and profound bulbar weakness and required nasogastric feeding from birth. A feeding gastrostomy was inserted at 9 months of age. She continued to have severe bulbar and limb weakness with dropped head at 5 years of age. Patient 2 and 3 did not have ocular signs at the time of initial presentation during infancy and at 2 years of age respectively. None of the patients attained independent walking. Patient 3, currently aged 16 years continues to be wheelchair bound and has only mild non-progressive bulbar weakness with normal cognitive development. Muscle biopsy in patient 1 and 3 showed predominant myopathic features admixed with small sized (atrophic/hypoplastic) fibres. Next generation sequencing confirmed the presence of a homozygous loss of function VAMP1 mutations in all three patients: A single nucleotide deletion resulting in frameshift: c.66delT (p.Gly23AlafsTer6) in patient 1 and nonsense mutations c.202C>T (pArg68Ter) and c.97C>T (p.Arg33Ter) in patient 2 and 3 respectively. Minimal but definite improvement in muscle power with pyridostigmine was reported in patients 1 and 2. This is the first report of VAMP1 mutations causing CMS from the Indian subcontinent, describing a clinically recognizable severe form of VAMP1-related CMS and highlighting the need for a strong index of suspicion for early genetic diagnosis of potentially treatable CMS phenotypes., Competing Interests: Declaration of competing interest None., (Copyright © 2021 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2021
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