AI Summary
A 56-year-old woman has experienced a progressive gait imbalance for the past 10 years, along with other movement disorders. She has been diagnosed with an autosomal-dominant spinocerebellar ataxia 48 caused by a mutation in the STUB1 gene. This case represents a unique manifestation of the disease.
A 56-year-old woman noticed progressive gait imbalance 10 years ago. Two years later she developed upper limb dysmetria and action tremor, followed by progressive dysarthria. Since the age of 50 years, she has also had an incapacitating jaw-opening oromandibular dystonia (Video 1). These movements are extremely limiting and have led to difficulty eating and noticeable weight loss. Her medical history is significant for a mood disturbance, and her maternal grandmother had an undiagnosed gait disorder. The brain MRI showed cerebellar atrophy (Figure). Whole-exome sequencing found a heterozygotic pathogenic variant NM_005861.4: c.672dup: p.(Arg225Alafs*14) in the STUB1 gene, compatible with an autosomal-dominant spinocerebellar ataxia 48.1 Other movement disorders have been described as associated with STUB1 mutations, such as chorea, tremor, generalized dystonia, myoclonus, and ataxia.2 However, this case represents a very unusual manifestation, expanding the current phenotype spectrum of STUB1-related ataxias.