Objective: To report a case of dystonia that adds to the growing body of literature regarding the genotypic variants associated with the ANO3 gene implicated in DYT24

Background: Autosomal dominant craniocervical dystonia caused by pathogenic variants in the ANO3 gene were linked to the dystonia locus DYT24 and first described in 2012. Since then multiple patients with different variants in the gene with age of onset varying from early childhood to late adulthood and a heterogenous phenotypic spectrum have been reported

Method: An 82 year old woman of German ancestry and limited family history presented with symptoms at the age of 40 involving clenching of left fist in addition to intermittent tremors in the left hand. She noticed flexion in the left upper extremity over the next decade and blinking more often with face pulling to the left. Over the last decade she walks with a limp with stiffening and dragging of her left foot. She also notices the right side of her body getting involved. These patterned movements are induced by action and tend to cause a sense of pain with sensitivity to touch particularly on the left side

Results:
Physical exam was pertinent for mild head shift to the left with laterocollis to the right, frequent eye blinks, jerky postural and terminal kinetic tremors, curling of toes of right foot and flexion at the wrists after repetitive movements.The patient grasped the pen tightly while writing and drawing jerky spirals with her left hand. Gait revealed dystonic hand postures during arm swing. MRI Brain was unremarkable. Genetic testing with sequence analysis and deletion/duplication testing of the genes in the Invitae Dystonia Comprehensive Panel revealed a heterozygous variant in ANO3 gene at exon 27 c.2812G>A (p.Val938Ile)

Conclusion: This case report expands the phenotypic spectrum of DYT24 associated with ANO3 gene mutations. It illustrates the clinical evolution from a focal dystonia to a nearly generalized dystonia over four decades of adult life and may suggest the natural history of disease progression that was seen in our elderly patient. Our patient had no symptomatic benefit from pharmacotherapy. Pallidal (GPi) deep brain stimulation (DBS) might be helpful in at least a subset of these patients and she is currently undergoing evaluation for DBS. Further cases are needed to evaluate the nature of DBS response particularly in late onset ANO3 dystonia patients

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-novel-ano3-variant-associated-with-generalized-dystonia-in-an-elderly-woman/