La Paraparesi spastica ereditaria in Sardegna: epidemiologia e studi di caratterizzazione genotipo-fenotipo

Objective:The hereditary spastic paraplegias (HSP) constitute a clinically and genetically heterogeneous group of rare neurodegenerative disorders characterized by spastic gait with weakness in the legs and additional signs in "complicated" forms. This study aims to explore the epidemiological, clinical, and genetic variability of HSPs among Sardinians, a population of peculiar ethnicity.Methods:A population-based prevalence study was performed in north-western Sardinia between January 2000 and December 2010. Multiple sources were used for case ascertainment. Familial and sporadic cases were diagnosed according to generally accepted criteria, and clinical diagnoses were validated by expert neurological examination, clinical data and pedigree information were recorded and blood samples drawn for genetic testing.Results:On 31 December 2010, the total crude prevalence was 19.9 per 100,000 (95% CI: 18.4- 21.4). AD-HSP contributed to most of the burden with a prevalence of 17.5 per 100,000, with 76 % of the prevalent cases presenting the same largeSPASTdeletion, encompassing the 3'-UTR. Indeed, in some island inner areas, the geographic isolation favoured the spread of a SPG4 kindred from few founders. Most of patients presented a mild disability as well as the members of another SPG4 family in southern Sardinia, with a small gene deletion encompassing the 5'-UTR. A 17-year-old boy from the center of the island, presented the clinical features of Infantile Ascending Hereditary Spastic Paraplegia (IAHSP), and carried a novel mutation in theASL2.Conclusions:The prevalence of HSP among Sardinians is high compared with other Western European populations and the specific socio-demographic characteristics of Sardinians may account for this finding. The study of the genes flankingSPG4as disease modifying factors is worthwhile.