Objective: This audit reviewed Huntington’s Disease (HD) diagnostic and predictive testing in New Zealand’s lower North Island. Key objectives included evaluating the frequency of pre-test genetic counseling and identifying the specialties of requesting practitioners. Additionally, the audit assessed post-result counselling referrals for positive cases, follow-up testing for negative cases, and potential ethnic variations in testing patterns.

Background: There have not been any audits of HD predictive and diagnostic testing in Aotearoa, New Zealand published in the literature. This audit aimed to review whether HD testing in New Zealand was in line with Australasian and international guidance.

Method: All HD genetic testing requests for the region from January 2018 to November 2022 were obtained through the genetics laboratory. Demographic information was obtained through the National Health Index (NHI) database.

Results: Predictive Testing: All but one test was requested by the genetics service and preceded by genetic counseling.

Diagnostic Testing: 80% of diagnostic requests originated from neurologists; five came from non-neurology services, and three had unavailable requester details. Of the eight positive diagnostic cases, five were referred to genetics, while three lacked referral records and required further investigation.

Ethnicity & Demographics: 87% of positive cases identified as NZ European, 3% as Māori/NZ European, and 2% as Asian. While Māori comprise approximately 18% of the lower North Island population, they represented 15% of negative test results. This study was not statistically powered to analyze ethnic disparities.

Conclusion: Overall, HD genetic testing practices in the lower North Island were consistent with Australasian and international guidelines. All predictive tests were requested through the genetic service, apart from one case where the details are unclear. Most positive diagnostic tests were referred to the genetics service. We reviewed the context of three cases not referred after positive diagnostic tests, and concluded it was appropriate not to have referred them. A HD testing guideline would likely be beneficial, particularly to assist non- neurology physicians in rural regions.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/huntingtons-disease-genetic-testing-practices-in-the-lower-north-island-of-new-zealand/