Genetic diversity of the IL-4, IL-4 receptor and IL-13 loci in mestizos in the general population and in patients with asthma from three subpopulations in Mexico.

Asthma is an inflammatory airway disease characterized by increased serum IgE levels, mucus hypersecretion and infiltration of inflammatory cells, and is a multifactorial disease that exhibits genetic heterogeneity. Polymorphisms in the interleukin-4 (C-590T), interleukin-4 receptor (ile50val and gln576arg), and interleukin-13 (arg130gln) genes have been described as susceptibility alleles for asthma. This study was designed to determine whether asthma susceptibility is influenced by genotypic and allelic distribution of the above polymorphisms in three Mexican subpopulations. Four hundred and thirty-seven subjects from three Mexican subpopulations were classified into two groups: general population and affected/unaffected and genotyped for the above polymorphisms. We compared the distributions of the loci in the groups. In addition, we undertook association analysis between these loci and asthma phenotype in each affected/unaffected group, and determined Nei's genetic distance between the three subpopulations. The allelic and genotypic distributions of the polymorphisms differed between the three subpopulations. There was no association between any of the polymorphisms and asthma phenotype. However, there was a differential distribution of haplogroups (P < 0.0001) between the affected and the unaffected groups from the subpopulations of Jalisco and Guerrero. The genetic distribution of the four polymorphisms in the subpopulations did not influence susceptibility to asthma. Furthermore, the difference in the prevalence of asthma in these subpopulations is not attributable to the genetic background for the four polymorphisms analysed. However, haplogroup analysis suggests that the interaction of the polymorphisms and other predisposing alleles leads to the expression of the clinical phenotype.

Heart rate variability in myocardial infarction with and without malignant arrhythmias: comparison with heart transplant recipients and normal subjects.

Myocardial autonomic denervation occurs after acute MI. This process is followed by a reduction of heart rate variability (HRV) and an increase of malignant ventricular arrhythmias and sudden death. This study investigated whether there are any significant differences in HRV among the population of MI who did and did not have malignant ventricular arrhythmias (MVAs), normal subjects and heart transplant recipients, the paradigm of the denervated heart. We studied 25 subjects aged 42 +/- 17 years, with normal clinical and cardiac noninvasive evaluation (group A); 70 patients aged 57 +/- 14 years, who had MI but no arrhythmic event in 36 months of follow-up (group B); 13 patients with MI aged 65 +/- 9 years, who had had sustained VT, VF, or sudden death (group C); and 16 cardiac transplant recipients aged 35 +/- 14 years (group D). The ECG was sampled for 256 seconds. We calculated, in time and frequency domain, the standard deviation of the RR cycle length and the spectral component's very low frequency (< 0.05 Hz), low frequency (0.05-0.15 Hz), and high frequency (0.15-0.35 Hz). The values of HRV in group A were significantly greater than in groups B, C, and D (P < 0.001) and greater in group B than in groups C and D (P < 0.001). Groups C and D did not differ (P = 0.610). These data indicate that HRV of patients who have had an MI and MVAs is very similar to that of heart transplant recipients. This is an indirect evidence that myocardial autonomic denervation may play an important role in the genesis of malignant arrhythmic events.