[Hyperhomocystinemia and 677C T methylenetetrahydrofolate reductase polymorphism as a cardiovascular risk factor in childhood]. / Hiperhomocistinemia y polimorfismo 677C T de la 5,10-metilenotetrahidrofolato reductasa en hijos de pacientes con enfermedad coronaria prematura.

BACKGROUND: Factors related to hyperhomocystinemia in the pediatric population of our geographical area with a parental history of premature coronary disease (PCD) are not well known. OBJECTIVES: To evaluate the possible association between plasma total homocysteine (tHcy), the B vitamins involved in its metabolism (folate, vitamin B12 and B6), and 677C T polymorphism of methylenetetrahydrofolate reductase (MTHFR) in a group of children with a parental history of PCD. METHODS: A cross-sectional analytical study of 80 children (aged 5-18 years old) with a parental history of PCD was performed. Values found in these children were compared with reference values for similar age groups. Plasma tHcy and vitamin B6 were evaluated by high-performance liquid chromatography with fluorometric detection. Folate and vitamin B12 concentrations were determined by radioimmunoassay. Detection of 677C T polymorphism of MTHFR was performed using polymerase chain reaction amplification and Hinfl digestion. Statistical analysis was performed using the SPSS program, version 10.0. Concentrations of tHcy and vitamins were compared using the Mann-Whitney U-test and Spearman's correlation coefficient. The association between phenotype, hyperhomocystinemia and low vitamin concentrations was analyzed using the chi-squared test. ResultsPlasma tHcy values in the children aged more than 10 years with a parental history of PCD were significantly higher (p < 0.001) than the reference values. Vitamin B12 levels were significantly lower (p 0.015), but neither folate nor vitamin B6 levels differed from the reference values. A negative correlation (p < 0.0001) was observed between tHcy and folate (r 0.47) and between tHcy and vitamin B12 levels (r 0.51). Eighty percent of the children with the TT genotype of MTHFR showed hyperhomocystinemia. Suboptimal vitamin B levels were also associated with the TT genotype of MTHFR. CONCLUSIONS: Hyperhomocystinemia detected in children with a parental history of PCD is associated with the TT genotype of MTHFR and with low folate levels. Because hyperhomocystinemia can be corrected by vitamin B supplementation, tHcy determination is recommended in the offspring of patients with PCD.

[The relationship of lipoprotein(a) to metabolic control in infantile-juvenile diabetes mellitus]. / Relación de la lipoproteína (a) con el control metabólico en la diabetes mellitus infanto-juvenil.

Lipoprotein (a) has become of great interest as a biochemical marker for predicting the risk of developing cardiovascular alterations, with increased levels suggesting patients at a higher risk. We have realized a study of the plasma concentrations of lipoprotein (a) and other constituents of lipoprotein metabolism in children diagnosed with diabetes mellitus type I in relationship to the levels of metabolic control, the time of evolution of the disease and the presence or not of microalbuminuria (albumin in the urine greater than 30 micrograms/min). The study population was comprised of 211 children, between the ages of 3 and 18 years of age, divided into three groups according to the time of evolution of the disease: beginners (n = 15), time of evolution less than or equal to 5 years (n = 99) and more than 5 years (n = 92). All determinations were performed on specimens collected after 10 hours of fasting and before the morning dose of insulin. The following determinations were made: total cholesterol, triglycerides, cHDL, cLDL, cVLDL, Apo AI, Apo B, lipoprotein (a), albumin excretion rate (AER), glucose, fructose, glycosylated hemoglobin and creatinine clearance. We found significant differences between the groups in function of the existence of microalbuminuria and if the time of evolution of the disease exceeded 5 years. In conclusion, it appears that metabolic control does not influence the concentrations of lipoprotein (a), with an increased risk of cardiovascular alterations in those patients with a long disease evolution an those that have microalbuminuria.