The high prevalence of hereditary spastic paraplegia in Sardinia, insular Italy

The few epidemiological studies conducted to date on the heterogeneous group of hereditary spastic paraplegias (HSPs) indicate a prevalence of 1.27-12.1 per 100,000. This study aims to explore the epidemiological, clinical, and genetic variability of HSPs among Sardinians, a population of peculiar ethnicity.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.Sixty-seven HSP patients were included in the study: 59 belonged to 11 families with autosomal dominant transmission (AD-HSP), three cases were from two unrelated autosomal recessive families, and the remaining five cases were apparently sporadic. On 31 December 2010, the total crude prevalence was 19.9 per 100,000 (95 % CI 18.4-21.4), while the crude prevalence of AD-HSP was 17.5 (24.4 M, 15.7 F; M:F ratio 1.55). The mean age at examination was 48.4 years, and the mean age at onset of HSP was 36.6 years. A molecular diagnosis was obtained in 82.1 % of the cases (52 cases with mutations in SPAST/SPG4, two in SPG7, and one in SPG11).The prevalence of HSP among Sardinians is high compared with other Western European populations. The multiple search strategy used in this study and the specific socio-demographic characteristics of Sardinians may account for this finding.