Age and gender effects on 15 platelet phenotypes in a Spanish population.

INTRODUCTION: Several studies have analysed the platelet parameters in human blood, nevertheless there are no extensive analyses on the less common platelet phenotypes. The main objective of our study is to evaluate the age and gender effects on 15 platelet phenotypes. METHODS: We studied 804 individuals, ranging in age from 2 to 93 years, included in the Genetic Analysis of Idiopathic Thrombophilia 2 (GAIT 2) Project. The 15 platelet phenotypes analysed were the platelets counts, platelet volumes, plateletcrits, immature platelet fraction (IPF) and platelet function assay (PFA). A regression-based method was used to evaluate the age and gender effects on these phenotypes. RESULTS: Our results were consistent with the previously reported results regarding platelet counts and plateletcrit (PCT). They showed a decrease with increasing age. The mean platelet volume (MPV), platelet distribution width (PDW) and platelet-large cell ratio (P-LCR) increased with age, but did not present any gender effect. All the IPF phenotypes increased with age, whereas the PFA phenotypes did not show any relation to age or gender. DISCUSSION: To sum up, our study provides a comprehensive analysis of the age and gender effects on the platelet phenotypes in a family-base sample. Our results suggest more reasonable age stratification into two distinct groups: childhood, ranging from 2 to 12 years, and the mature group, from 13 to 93 years. Moreover, the PFA phenotypes were maintained constant while the platelet counts, the MPV and IPF levels vary with age.

Genetic determinants of platelet large-cell ratio, immature platelet fraction, and other platelet-related phenotypes.

INTRODUCTION: Platelets play a significant role in arterial thrombosis and are involved also in venous thrombosis. The genetic determinants of several platelet-related phenotypes have been studied previously. However, to the best of our knowledge, the genetic determinants of other platelet phenotypes have not been reported such as platelet-large-cell ratio (P-LCR) index, immature platelet fraction (IPF) parameters and overall platelet function measured through the PFA-100 system. MATERIALS AND METHODS: As part of the GAIT-2 (Genetic Analysis of Idiopathic Thrombophilia 2) Project, 935 individuals from 35 large Spanish families, ascertained through a proband with thrombophilia, were studied. Using variance component methods, implemented in the SOLAR package, the heritability of the following sets of platelet-related phenotypes was determined: platelet count and indices, IPF, and platelet function. RESULTS AND CONCLUSIONS: High heritabilities of the platelet count and index phenotypes (from 0.41 to 0.64) were found, especially for those related to platelet volume. The heritabilities of the IPF phenotypes, as a measure of platelet turnover, were the highest (from 0.65 to 0.69). The heritabilities of the platelet function phenotypes were high also (0.45 and 0.62). The covariate age influenced all of the platelet phenotypes. Smoking influenced the platelet indices related to platelet volume and all the IPF phenotypes. Venous thrombosis showed a heritability of 0.67. We did not find a genetic correlation between any of the platelet-related phenotypes and venous thrombosis. The high heritabilities found for all of the platelet phenotypes provid promising data for the identification of new genes that underly these phenotypes.