Relationship between apo(a) length polymorphism and lipoprotein(a) concentration in healthy Ivorian subjects with single or double apo(a) isoforms.

OBJECTIVES: To determine the relationship between apo(a) size and Lp(a) concentration in healthy Ivorian subjects. METHODS: Serum Lp(a) was measured by immunonephelometry and electroimmunodiffusion, and apo(a) size determined by immunoblotting. RESULTS: Both assay methods provided comparable information. Lp(a) concentrations showed a non-Gaussian distribution and skewed towards higher values. Apo(a) isoform size distribution exhibited three frequency peaks at 18, 22 and 25 kringles. Single and double apo(a) isoforms were detected in 36% and 64% of subjects, respectively. Lp(a) values were higher in subjects with double isoforms, the major isoform being of lower size. An inverse correlation between apo(a) size and Lp(a) concentration was found, apo(a) size accounting for more than 30% of Lp(a) concentration in "single-band" group, whereas being weaker in "double-band" group. Low size isoforms were associated with higher Lp(a) concentrations, high size isoforms with higher variability. CONCLUSIONS: Lp(a) concentrations were inversely correlated to apo(a) size. This study has shown the relationship between apo(a) size and Lp(a), the influence of apo(a) size varying according to the phenotype. Apo(a) "double isoform" phenotype confers elevated levels to Lp(a) in healthy Ivorian subject.

A different approach to analyzing age-related HbA1c values in non-diabetic subjects.

Using appropriate statistical tests and taking into account the analytical performance of hemoglobin A1c (HbA1c) measurements, is it useful to establish HbA1c age-related values in non-diabetic subjects? Non-diabetic subjects (n=135, 72 women and 63 men) from the neuromuscular department of the Pitié-Salpétrière Hospital (Paris) were involved in our study. Subjects were divided into two groups related to age: 51 patients under 50 years old and 84 subjects aged 50 years or more. Fasting plasma glucose and HbA1c measurements were respectively performed by enzymatic assay using the hexokinase method and high-performance liquid chromatography based on the ion exchange methodology with high precision. We first checked the normality of HbA1c distribution using the Kolmogorov-Smirnov test. Then we compared mean HbA1c in the two age subgroups using the Student's t test. Mean HbA1c was significantly (p<0.0001) higher in the subgroup aged 50 years or more (mean HbA1c=5.2%) than in younger subjects (mean HbA1c=5.0%). Then plots were drawn to check the relationship between HbA1c and age. Under the hypothesis of linearity, determination coefficients (R2) were calculated. However, considering their low values, this hypothesis must be rejected and other factors than age must be retained to explain HbA1c variability.