Background: In adults, a low density lipoprotein cholesterol (LDL-C)/apolipoprotein B-100 (ApoB) ratio is an indicator of ApoB-enriched small dense LDL, which is associated with premature coronary artery disease (CAD). Since this LDL subclass may be inherited, we investigated whether a low LDL-C/ApoB ratio was associated with a positive family history of premature CAD in young children.
Methods: Subjects were 66 children aged 7 to 11 years who were recruited through a school-based family history survey, flyers, and hospital newspaper advertisements. They were divided according to family history and assessed for fatness, blood pressure, lipids, lipoproteins, and apoproteins.
Results: Family history interacted with gender such that girls with a positive family history had a lower LDL-C/ApoB ratio than girls with a negative family history, while the opposite was true in boys; ie, family history-positive boys had a higher ratio than family history-negative boys. The association of a low ratio with a positive family history was seen most clearly in white girls. Family history-positive whites had higher ApoB than family history-negative whites, whereas the pattern was reversed in the blacks. The LDL-C/ApoB ratio and ApoB were not related to other CAD risk factors such as fatness, blood pressure, or other lipids and lipoproteins.
Conclusion: In young children, a low LDL-C/ApoB ratio and high ApoB levels were associated with a positive family history of CAD only in the white girls, suggesting that this group is at increased risk of genetically mediated CAD.