RESUMO
Elevated levels of lipoprotein(a) [Lp(a)] are associated with increased risk for coronary heart disease (CHD). However, racial differences in both Lp(a) levels and their associated CHD risk are observed, with African Americans having, on average, higher Lp(a) levels than US whites but not the expected increase in CHD risk. We determined Lp(a) levels and their correlates in a large cohort (n = 2379) of black and white girls, ages 9 to 10 years, at the baseline visit of a longitudinal study of obesity development, the National Heart, Lung, and Blood Institute Growth and Health Study. Lp(a) levels were available for 1269 girls. The median Lp(a) level in black girls was over 3-fold higher than that in white girls. Associations were examined between Lp(a) levels and low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, apolipoprotein B, triglycerides, adiposity, pubertal maturation stage, body fat patterning (triceps/truncal skinfold ratio), and dietary fat (Keys' score). In black girls multiple regression analysis identified LDL-C (P <.001) and adiposity (P =. 08) as predictors of Lp(a) levels. In white girls only LDL-C (P =. 02) was associated with Lp(a). In conclusion, the level of Lp(a) was significantly higher in black girls. Our study also revealed a racial difference in correlates of Lp(a), such as LDL-C and adiposity. Whether this racial difference is due to an underlying biologic difference or is merely a reflection of a greater statistical power to detect a relationship with the level, which was 2.5-fold higher in black girls than in white girls, needs further investigation.
Assuntos
População Negra , Lipoproteína(a)/sangue , População Branca , Análise de Variância , Antropometria , Criança , Comportamento Alimentar , Feminino , Humanos , Estudos Longitudinais , Análise de Regressão , Maturidade Sexual , Estatísticas não Paramétricas , Estados UnidosRESUMO
OBJECTIVE: In our general experience, about 2% of samples referred for fragile X testing showed positive results on Southern blot analysis. The aim of this project was to determine whether screening criteria could be developed to increase the proportion of positive test results without sacrificing sensitivity. STUDY DESIGN: We retrospectively analyzed nine clinical characteristics from patient records of 273 male and 62 female pediatric probands (average age, 5.7 years) referred for fragile X testing. The characteristics included mental retardation, family history of mental retardation, large or prominent ears, elongated face, attention deficit hyperactivity disorder, autistic-like behavior, simian crease, macroorchidism, and hyperextensible joints. These were scored as 2 if present, 1 If borderline present, and 0 if absent. RESULTS: Analysis of the nine characteristics identified three (simian crease, macroorchidism, and hyperextensible joints) with low frequency and statistical insignificance, which were therefore eliminated. With the use of the remaining six characteristics, If a score of 5 or more was used as the criterion for requesting fragle X testing, then close to 60% of those tests from our patient population could have been eliminated without missing any positive cases. The validity of our threshold score of 5 was subsequently confirmed among an additional six cases of fragile X syndrome. CONCLUSION: With our simplified six-item clinical checklist, 60% of testing could have been eliminated, thereby improving the cost-effectiveness of fragile X testing and increasing the proportion of cases with positive results by threefold.