Influence of age, sex and ethnicity on platelet count in five Italian geographic isolates: mild thrombocytopenia may be physiological.

Two population-based studies recently identified a high prevalence of unexplained thrombocytopenia, especially in men and older people (Biino et al, 2011; Santimone et al, 2011). Moreover, these studies reported a wide variability in the prevalence of thrombocytopenia in different villages. Further investigation concluded that the development of thrombocytopenia derived from the interaction of three factors: genetic factors, which set the 'basic' platelet count, gender-related factors, which result in lower platelet count in men and age-related factors, which are responsible for a progressive decrease in the platelet count over a life-time (Biino et al, 2011). To further assess this topic, we evaluated the determinants of the platelet count in 7266 inhabitants of five geographic isolates located in different Italian regions: Cilento National Park, in south Italy (n = 1837) (Siervo et al, 2010), upper Borbera valley, in the northwest of Italy (n = 1551) (Traglia et al, 2009), Carlantino village, in the south-eastern part of Puglia region (n = 1265) (Tepper et al, 2008), Genetic Park of Friuli Venezia Giulia (FVG), in north-eastern Italy (n = 1516) (Girotto et al, 2011), and South Tyrol, the northern-most Italian region (n = 1097) (Pattaro et al, 2007). All these populations are characterized by an old settlement, a small number of founders, high endogamy rates, slow or null population expansion and negligible immigration. All enrolled subjects (age range 1-103 years) provided socio-demographic and genealogical data, as well as a detailed medical history, and underwent physical examination and blood sampling in local consulting rooms. Study protocols were approved by the ethical committees of the different institutions, and all participants in the study gave their informed consent.