Differential fertility associated with common apolipoprotein E alleles in postreproductive aged subjects.

Objective: To investigate the possible impact of apolipoprotein E (APOE) polymorphisin on reproductive efficiency. Design: Population study. Setting: University Departments and a Laboratory of National Research Council. Patient(s): One hundred sixty healthy unrelated subjects of postreproductive age. Intervention(s): Peripheral blood collection and questionnaire administration. Main Outcome Measure(s): Apolipoprotem E genotypes were detected after PCR amplification and CfoI digestion; plasma total cholesterol was assayed. Result(s): The mean number of children of e *2 allele carriers (2.4) was lower than that of e *3/e *3 and e *4/e *3 subjects (3.9). The trend was similar (2.8 vs. 4.8) when the number of pregnancies was considered. Moreover, there was a clear inverse relationship between number of children and e*2-carrying genotype proportions (chi(2) for trend = 6.3). Conversely, the e*3/e*3 genotype was associated with the highest number of children and pregnancies (3.9 and 4.9, respectively), and the e*4/e*3 genotype, with intermediate values (3.7 and 4.4). Carriers of e*2 allele also showed the lowest levels of total cholesterol. Conclusion(s): The e*2 allele seems to be associated with the lowest reproductive efficiency and the e*3 allele, with the highest. The different total cholesterol levels associated with APOE genotypes could have an effect on steroidogenesis and determine as a consequence the observed differential fertility.