Octogenarian Kindred: hyper-alpha-lipoproteinemia

Plasma C-reactive protein in subjects with hypo/hyperalphalipoproteinemias

Hypoalphalipoproteinemia (Hypo-A), a lipid disorder characterized by low high-density lipoprotein (HDL)-cholesterol (HDL-C) levels, is frequently associated with an increased risk of suffering future coronary heart disease (CHD). Conversely, hyperalphalipoproteinemia (Hyper-A) is a characterized by high HDL-C concentrations and is possibly associated with longevity and protection against CHD. Whether plasma C-reactive protein (CRP) level, an emerging marker of CHD risk, may be influenced by either extremely low or high HDL-C concentrations is yet to be determined. Plasma levels of lipids and CRP have been measured in 52 middle-aged men and women, clinically free of CHD, including 20 subjects with Hypo-A, 12 with Hyper-A, and 20 healthy normolipemic age-matched controls. CRP levels were the highest in Hypo-A [0.22 mg/dL (interquartile range, 0.15 to 0.44)], the lowest in Hyper-A [0.03 mg/dL (0.02 to 0.07)], and intermediate in the control group [0.10 mg/dL (0.05 to 0.20)]. Differences in plasma CRP concentrations were significant between Hypo-A and the other 2 groups, as well as between Hyper-A and controls. Plasma CRP levels showed a particularly strong correlation with plasma HDL-C concentrations (r = -.66, P <.001). In multivariate models, HDL-C represented the only significant predictor of circulating levels of CRP. In conclusion, in subjects with Hypo-A or Hyper-A, HDL-C levels may account for plasma CRP variations independent of other potential cardiovascular risk factors.

Lipoproteins in the elderly

Changes in lipid metabolism with age result in lower total serum cholesterol and low-density lipoprotein concentrations. There is no evidence that longevity and lipid profiles are influenced by genetic make-up. It is difficult to establish an optimum total serum cholesterol in the elderly but values established in younger subjects give a guide. High-density lipoprotein may be even more protective in the elderly and could turn out to be a better predictor of coronary disease. Screening for the treatment of hypercholesterolaemia should be carried out in the elderly. Although death is an inevitable fact, intervention in, for example, recently retired, apparently disease-free subjects is important. The first approach should be the introduction of changes in life style (increased exercise, stopping smoking, improved diet). Drugs may also be introduced if these interventions fail. Although drug therapy in the elderly may pose immediate problems due to poor renal and hepatic function, the adverse effects of long-term use have less relevance in the elderly.

Lipid phenotypes, apolipoprotein genotypes and cardiovascular risk in nonagenarians

Despite great interest in the role of lipids in overall and disease-free survival, virtually no information is available on the lipids, lipoproteins and apolipoproteins of persons over 90 years of age. Furthermore, the genetic underpinnings of atherosclerosis and the particular genetic factors responsible for protection against coronary artery disease remain speculative. In Bloomfield, Nebraska, we studied 41 nonagenarians (10 males, 31 females), with a mean age of 92.7 years, in whom lipids, lipoproteins, apolipoproteins and restriction fragment length polymorphisms (RFLPs) of genes for apolipoprotein B (apo B), aop AI and apo CIII were assessed. Nearly complete historical, physical and laboratory data were obtained on 39 subjects. The mean diastolic and systolic blood pressures for this group were nonhypertensive, body mass indices (weight/height2) had a mean of 23.9 and triceps skinfold thickness measurements an overall mean of 14.8 mm. The mean total serum cholesterol was 5.42 mmol/l. HDL-cholesterol levels in females persisted to be higher when compared to males (P less than 0.013). The allele frequencies for apo AI (MspI and PstI), apo CIII (Sst) and apo B (XbaI) gene RFLPs were typical for larger population studies. In these preliminary studies, we did not identify a distinctive phenotype, genotype, or phenotype-genotype relationship. Diversity of cardiovascular risk was the hallmark of these nonagenarians.

Lipoproteins in familial hyperalphalipoproteinemia

Familial hyperalphalipoproteinemia is determined by a major gene and is characterized by high levels of high density lipoprotein cholesterol and longevity. To describe the plasma lipoproteins in this condition more completely, a kindred consisting of the proband, her affected father, add her two affected brothers was studied. Fasting plasmas were analyzed for lipoprotein lipids by combined preparative ultracentrifugal and precipitation methods. Levels of apolipoprotein A-1 and apolipoprotein A-11, the major apoproteins of high density lipoproteins, were assayed by radioimmunoassay. The flotation properties of very low density, low density and high density lipoprotein were determined by zonal ultracentrifugation, and the isolated high density lipoprotein subfractions were characterized according to their lipid and apoprotein compositions. Total cholesterol of all subjects was normal, but triglycerides were elevated (above the 90th percentile) in the two brothers. High density lipoprotein cholesterol ranged from 150 to 165 mg/dl in the proband and from 72 to 89 mg/dl in her relatives. Apolipoprotein A-1 was 318 mg/dl in the proband and 156 to 169 mg/dl in the siblings; respective apolipoprotein A-11 values were 67 and 82 to 83 mg/dl. The high density lipoprotein cholesterol and apolipoprotein A-1 and A-11 values for the relatives are above the 95th percentile for sex and age, while the levels of the proband are the highest recorded in our laboratories. On zonal ultracentrifugation, very low density lipoprotein and low density lipoprotein had normal flotation properties. High density lipoprotein was divisible into three populations, HDL2, HDL3L, and HDL3D (Sf(1,21,26 degrees C), 59, 2.9, and 1.7 respectively), each of which floated in its usual position. But HDL2 was grossly elevated, accounting for most of the rise in the high density lipoprotein fraction. The compositions of the high density lipoprotein fractions with respect to the major lipid and apoprotein classes did not differ from normal. Thus, in this kindred, high density lipoprotein was quantitatively rather than qualitatively unusual. It is of interest that hypertriglyceridemia and hyperalphalipoproteinemia coexisted in the siblings. These concurrent elevations differ from the expected reciprocal relationship between high density lipoprotein and very low density lipoprotein levels in plasma, and suggests that in some subject the two abnormalities may be independently transmitted.