Plasma lipoprotein composition, apolipoprotein(a) concentration and isoforms in beta-thalassemia.
Patients with homozygous beta-thalassemia show an abnormal lipoprotein profile. In asymptomatic heterozygotes the lipid pattern is less markedly affected but interestingly related to a diminished cardiovascular risk. The extent and significance of these findings are still a matter of debate and no data are available on lipoprotein(a) plasma levels. Seventy patients with homozygous beta-thalassemia (HT-P), 70 beta-thalassemia trait carriers (TT-C) and 70 sex and age-matched controls were investigated and their plasma lipoprotein profile and apo(a) phenotypes determined. In a subgroup of these same subjects (12 HT-P, 12 TT-C and 24 controls) and in 12 bone marrow-transplanted homozygous beta-thalassemic patients (BMT-P) plasma lipoprotein composition was assessed. HT-P disclosed significantly lower total-cholesterol, LDL-cholesterol, HDL-cholesterol, apo A-I, apo B plasma levels and higher triglyceride concentration than TT-C (-7, -11, -8, -8, -13 and +11%, respectively) or controls (-39, -50, -46, -32, -30 and + 35%, respectively). All lipoprotein subclasses were triglyceride-enriched, while LDLs were also protein-enriched and HDLs protein-depleted. TT-C disclosed a small but significant reduction in apo A-I and apo B plasma levels but only minor lipoprotein abnormalities with respect to the controls. BMT-P lipoprotein composition was intermediate between HT-P and normal subjects. Apo(a) plasma levels did not differ among the groups. A higher prevalence of 'small' apo(a) isoforms was present in HT-P. Within the same 'isoform group', apo(a) plasma levels were significantly lower in HT-P than in TT-C or controls. Since liver cirrhosis is almost always present in HT-P, it is conceivable that an altered hepatic apo(a) synthesis or catabolism due perhaps to diminished apolipoprotein glycation may be involved. In TT-C a partially improved cardiovascular risk profile was apparent (low hematocrit, low LDL-cholesterol and apo B), thus justifying the claim for a low prevalence of ischemic heart disease, but no Lp(a) plasma level modification could be detected.
Maioli
M
M
Institute of Internal Medicine, University of Sassari, Italy.
Vigna
G B
GB
Tonolo
G
G
Brizzi
P
P
Ciccarese
M
M
Donegà
P
P
Maioli
M
M
Fellin
R
R
D000293:Adolescent; D000328:Adult; D016632:Apolipoprotein A-I / Q000378:metabolism; D001054:Apolipoproteins A / Q000378:metabolism*; D001055:Apolipoproteins B / Q000097:blood; D016026:Bone Marrow Transplantation; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008074:Lipoproteins / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D014280:Triglycerides / Q000097:blood; D017086:beta-Thalassemia / Q000097:blood* / Q000628:therapy
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014280:Triglycerides; D002784:Cholesterol