title: Analysis of 12,517 inhabitants of a Sardinian geographic isolate reveals that predispositions to thrombocytopenia and thrombocytosis are inherited traits.
abstract: BACKGROUND
  Thrombocytopenia is a common finding in several diseases but almost nothing is known about the prevalence of thrombocytopenia in the general population. We examined the prevalence of thrombocytopenia and determinants of platelet count in a healthy population with a wide age range.
  
  
  METHODS
  We performed a cross-sectional study on 12,517 inhabitants of ten villages (80% of residents) in a secluded area of Sardinia (Ogliastra). Participants underwent a complete blood count evaluation and a structured questionnaire, used to collect epidemiological data.
  
  
  RESULTS
  We observed a platelet count lower than 150 × 10⁹/L in 3.2% (2.8%-3.6%) of females and 4.8% (4.3%-5.4%) of males, with a value of 3.9% (3.6%-4.3%) in the entire population. Thrombocytopenia was mild (platelet count: 100 × 10⁹/L-150 × 10⁹/L), asymptomatic and not associated with other cytopenias or overt disorders in most cases. Its standardized prevalence was quite different in different villages, with values ranging from 1.5% to 6.8%, and was negatively correlated with the prevalence of a mild form of thrombocytosis, which ranged from 0.9% to 4.5%. Analysis of platelet counts across classes of age revealed that platelet number decreased progressively with aging. As a consequence, thrombocytopenia was nearly absent in young people and its prevalence increased regularly during lifetime. The opposite occurred for thrombocytosis.
  
  
  CONCLUSIONS
  Given the high genetic differentiation among Ogliastra villages with "high" and "low" platelet counts and the substantial heritability of this quantitative trait (54%), we concluded that the propensity to present mild and transient thrombocytosis in youth and to acquire mild thrombocytopenia during aging are new genetic traits.
authors.affiliation: Institute of Molecular Genetics, CNR, Pavia, Italy. biino@igm.cnr.it
authors.forename: Ginevra
authors.initials: G
authors.lastname: Biino
authors.forename: Carlo L
authors.initials: CL
authors.lastname: Balduini
authors.forename: Laura
authors.initials: L
authors.lastname: Casula
authors.forename: Piergiorgio
authors.initials: P
authors.lastname: Cavallo
authors.forename: Simona
authors.initials: S
authors.lastname: Vaccargiu
authors.forename: Debora
authors.initials: D
authors.lastname: Parracciani
authors.forename: Donatella
authors.initials: D
authors.lastname: Serra
authors.forename: Laura
authors.initials: L
authors.lastname: Portas
authors.forename: Federico
authors.initials: F
authors.lastname: Murgia
authors.forename: Mario
authors.initials: M
authors.lastname: Pirastu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D015995:Prevalence; D011379:Prognosis; D012307:Risk Factors; D013921:Thrombocytopenia / Q000453:epidemiology / Q000235:genetics*; D013922:Thrombocytosis / Q000453:epidemiology / Q000235:genetics*; D055815:Young Adult
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