Background In this study we describe the clinical, and investigations profile of 7 cases of autosomal-recessive spastic-ataxia of Charlevoix-Saguenay (ARSACS).
Methods We performed retrospective chart review of genetically proven cases of ARSACS from our database. Additionally, we reviewed literature for reported cases of ARSACS from India.
Result All seven patients had onset within the first-decade. As per the available data, all had walking difficulty (7/7), spastic-ataxia (7/7), classical neuroimaging findings (7/7), sensory-motor demyelinating polyneuropathy (6/6), abnormal evoked-potentials (5/5) and thickened retinal nerve fiber layer (3/3). Exome sequencing revealed 8 pathogenic/likely-pathogenic unique variants (6 novel) in SACS gene. Additional 21 cases (18 families) of ARSACS that could be identified from India had similar clinical and investigational findings. The most common c.8793delA variant may have a founder effect.
Conclusion Our series adds to the previously reported cases of ARSACS from India and expands the genetic spectrum by adding 6 novel variants.
Objective aaMutations in the KMT2B gene have been identified in patients previously diagnosed with idiopathic dystonia. Literature on KMT2B-related dystonia is sparse in the Indian and Asian populations.
Methods aaWe report seven patients with KMT2B-related dystonia studied prospectively from May 2021 to September 2022. Patients underwent deep clinical phenotyping and genetic testing by whole-exome sequencing (WES). A systematic literature search was performed to identify the spectrum of previously published KMT2B-related disorders in the Asian subcontinent.
Results aaThe seven identified patients with KMT2B-related dystonia had a median age at onset of four years. The majority experienced onset in the lower limbs (n = 5, 71.4%), with generalization at a median duration of 2 years. All patients except one had complex phenotypes manifesting as facial dysmorphism (n = 4), microcephaly (n = 3), developmental delay (n = 3), and short stature (n = 1). Magnetic resonance imaging (MRI) abnormalities were present in four cases. WES revealed novel mutations in the KMT2B gene in all patients except one. Compared to the largest cohort of patients with KMT2B-related disorders, the Asian cohort, comprising 42 patients, had a lower prevalence of female patients, facial dysmorphism, microcephaly, intellectual disability, and MRI abnormalities. Protein-truncating variants were more prevalent than missense variants. While microcephaly and short stature were more common in patients with missense mutations, facial dysmorphism was more common in patients with truncating variants. Deep brain stimulation, performed in 17 patients, had satisfactory outcomes.
Conclusion aaThis is the largest series of patients with KMT2B-related disorders from India, further expanding the clinico-genotypic spectrum. The extended Asian cohort emphasizes the unique attributes of this part of the world.
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Clinical and genetic profile of patients with dystonia: An experience from a tertiary neurology center from India Debjyoti Dhar, Vikram V. Holla, Riyanka Kumari, Ravi Yadav, Nitish Kamble, Babylakshmi Muthusamy, Pramod Kumar Pal Parkinsonism & Related Disorders.2024; 120: 105986. CrossRef