Incidence and prevalence of Huntington disease (HD) in the Sultanate of Oman: the first Middle East post-<i>HTT</i>service-based study
Ferdinando Squitieri, Sabrina Maffi, Salma Al Harasi, Qasem Al Salmi, Barbara D’Alessio, Giovanni Capelli, Tommaso Mazza
Abstract
Huntington disease (HD) is a neurodegenerative, dominantly inherited disorder, which may result in a debilitating movements disorder and cognitive decline with progressive loss of independence. HD frequency in the Middle East has never been defined after the HTT gene discovery and cases of HD have been reported only sporadically.1 In July 2013, Italian League for Research on Huntington Disease Foundation was contacted by a family from Oman, who reported to be affected by HD since many generations. Indeed, that family may represent the largest HD cluster ever described in the Middle East, owing to a high number of intermarriages and subsequent increase in mutation heritability risk. Given the gaps in our knowledge about HD in the Middle East, we took the opportunity to study and determine the incidence and prevalence of HD in this region. We performed an observational, service based, study from August 2013 to March 2019 in the Muscat region, Sultanate of Oman. Prevalence was estimated on the number of affected and at-risk individuals, who were referred to the National Genetic Centre (NGC) of the Royal Hospital in Muscat, the main Ministry of Health Country health organisation. We are, therefore, confident to have an accurate representation of most HD cases and families who reside in this region. A priori risk, that is, the risk of disease associated with an individual at birth, was separated into groups: 50% risk (a first-degree relative is affected with or mutation-positive for HD), and >50% risk (an individual with both at-risk parents or one affected and one at-risk parent). All subjects were clinically evaluated by the Unified HD Rating Scale (UHDRS)2 and examined by the same neurologist (FS) with expertise in HD. Clinical characteristics, including age at onset, age at death and symptoms presentation, were recorded based on first relevant neurological and …