[Sib-sib correlations of cardiovascular risk factors: the Cuenca study]

To analyze the sib-sib correlation of the cardiovascular risk factors.

A cross-sectional study was made in 115 sibling pairs. Sociodemographic variables, weight, height, body mass index, systolic blood pressure, diastolic blood pressure and fasting plasma total cholesterol, LDL-C, HDL-C, apo A-I, apo B and Lp(a) concentrations. Partial correlation coefficients adjusted for age and body mass index for plasmatic lipid and lipoprotein levels in sibling pairs showed positive values range from 0.27 for triglyceride to 0.53 for apo B/apo A-I ratio (p < 0.005). Likewise, the intraclass correlation coefficients ranged from 0.20 to 0.48. Both coefficient were higher in brother-brother pairs than in sister-sister pairs. The Quetelet index coefficients were slightly lower than lipid coefficients, and showed similar values among the different kinds of sibling pairs. Blood pressure coefficients were low (p > 0.05).

An association for lipid and lipoprotein plasma concentrations has been evidenced in sibling pairs. This association is stronger in brother-brother pairs than in sister-sister pairs. This fact could indicate a sex linked heredability of lipid and lipoprotein levels. A weaker association for body mass index has been observed. Sib-sib aggregation of blood pressure levels is not significant.