Molecular diagnosis of Huntington's disease in Trinidadian families via triplet repeat primed PCR, fragment analysis, and nanopore sequencing

Background Huntington's disease (HD) is a neurodegenerative disorder caused by CAG expansions in the Huntingtin ( HTT ) gene. Due to its non-specific and variable phenotype, diagnosis requires clinical assessments and genetic testing. In the Caribbean, the genetic etiology of HD is underexplored due to the unavailability of genetic testing. Objective We investigated whether 32 participants from four multigenerational families from Trinidad and Tobago (T&T) presenting with Huntington-like symptoms carried HTT CAG expansions, and whether CAG length was related to decreasing age of onset with each generation. Methods Participants were genotyped using triplet repeat primed PCR followed by previously-established fragment analysis and a nanopore sequencing based method with a custom bioinformatics workflow. Results All symptomatic participants carried HTT CAG expansions (42–57 CAGs), confirming HD. Among participants aged 20–65 years (n = 24), clinical and genetic diagnoses were concordant for 22 participants (13 symptomatic with 42–57 CAGs, and nine asymptomatic with 13–27 CAGs). Two asymptomatic participants aged 22 and 43 years carried 46–47 and 37–39 CAGs, respectively. Among eight participants