Objective: To report the case of a patient from Iraq with a Huntington disease-like phenotype who was found to have a heterozygous trinucleotide repeat expansion in the JPH3 gene

Background: Huntington-like disease type 2 is caused by a CTG trinucleotide repeat expansion in the JPH3 gene. It classically affects people of Sub-Saharan African ancestry, but it has also been reported in Central and South America, likely due to an African founder mutation[1]. To our knowledge, it has not been reported in a patient from the Middle East. This female patient from Iraq developed abnormal choreiform movements in the eyes, face, and hands at age 40. Cognition started to decline at age 47, with increased forgetfulness and reliance on family for cooking and housework. Affective changes included anxiety and obsessive thoughts and behaviors regarding toileting and washing herself. Additional nonmotor symptoms included dysphagia, constipation, insomnia, and hypophonia. These symptoms have been gradually progressive. Family history is significant for a mother, two maternal uncles, and three sisters with similar movements, mood, and cognitive changes. All had symptom onset in their mid-30s to 40s. At the most recent clinical evaluation at age 54, she had limited range of ocular pursuit bilaterally, inability to suppress head movements with saccade initiation bilaterally, limited verbal output with mild dysarthria, motor impersistence, bradykinesia, moderate generalized chorea, and wide-based gait.

Method: The following genetic testing was ordered: Huntington’s disease trinucleotide repeat expansion analysis, spinocerebellar ataxia type 17 repeat expansion analysis, dentatorubral pallidoluysian atrophy repeat expansion analysis, C9orf72 repeat expansion analysis, whole exome sequencing, sequence analysis and deletion testing of the mitochondrial genome, ataxia repeat expansion analysis, JPH3 repeat expansion analysis.

Results: All genetic testing was negative except for JPH3 repeat expansion analysis, which revealed an allele with 49 CTG repeats. This confirmed the diagnosis of Huntington-like disease type 2.

Conclusion: This patient from Iraq with no known African ancestry has Huntington-like disease type 2. This case highlights the importance of considering genetic testing for JPH3 repeat expansions in patients with a Huntington disease-like phenotype and Iraqi ancestry. Genetic testing of her affected living family members is in progress.

References: [1] Walker RH, Gatto EM, Bustamante ML, et al (2018) Huntington’s disease-like disorders in Latin America and the Caribbean. Parkinsonism & Related Disorders 53:10–20. https://doi.org/10.1016/j.parkreldis.2018.05.021

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MDS Abstracts - https://www.mdsabstracts.org/abstract/huntington-like-disease-type-2-caused-by-a-jph3-repeat-expansion-in-a-patient-from-iraq/