Genotype and phenotype correlations in diabetic patients in Uruguay

To differentiate among different types of diabetes is becoming an increasingly challenging task. We investigated whether the patient's genetic profile is useful to identify the particular type of diabetes, to determine the corresponding hyperglycemia pathogenesis and treat accordingly. Three hundred and thirty-eight diabetic patients, diagnosed according to American Diabetes Association criteria, were recruited from 2004 to 2008 in diabetes health reference centers. We analyzed the major gene for type 1 diabetes susceptibility (HLA DQ/DR). In order to improve our understanding of the pathogenesis of the resulting hyperglycemia and to implement a more adequate treatment for the patients, we reclassified our sample according to the presence or absence of the genetic markers. We found that a higher percentage of people than expected have immunological disease, independent of their phenotype, with a relative risk of 4.62 (95% confidence interval). This methodology allowed us to establish an association between the genotype and its resulting phenotype. We found significant differences; the phenotypic classification did not reflect immunological disease based on genotype. Moreover, when we examined markers, body mass index and age of onset, we found that many people have an intermediate phenotype between type 1 and type 2. This genetic data can help provide an accurate definition of the disease and would therefore provide the physician a better possibility of providing adequate treatment.

Prevalence of vitamin D receptor gene polymorphism in a Uruguayan population and its relation to type 1 diabetes mellitus

Vitamin D has important immuno-modulatory properties and it influences insulin secretion. It acts through a vitamin D receptor (VDR), for which several gene polymorphisms have been described. The Uruguayan population presents several epidemiological characteristics that make it different from that of other counties, including other Latin-American countries. It went through miscegenation processes, with a tri-hybrid European, Amerindian and African origin, with no contribution from isolated Amerindian communities. Such differences have important consequences for the relationship between frequencies of several genes in the general population and their association with the diabetes mellitus. We examined the prevalence of VDR gene polymorphisms in the general population and their relation to type 1 diabetes in a parent-case design. One hundred unrelated individuals from the general population and 45 parent-patient triads with a child affected with type 1 diabetes were genotyped for FokI, BsmI and TaqI VDR gene polymorphisms by RFLP-PCR. We used a transmission disequilibrium test to assess preferential transmission of parents to affected offspring. The prevalence of the three VDR polymorphisms was: allele F = 48%, B = 35%, T = 64%. The f, b, T alleles and heterozygous genotypes were found at a high frequency in this population. Among 36 informative heterozygous parental genotypes, 30 transmitted the F allele (probability of transmission = 83%). The other two polymorphisms did not show significant transmission. We suggest that FokI polymorphism indicates susceptibility to type 1 diabetes mellitus in the Uruguayan population.

Deletion of chromosome 3 and a 3;20 reciprocal translocation demonstrated by chromosome painting

The combined use of high resolution banding and chromosome painting techniques allowed us to identify a reciprocal translocation involving chromosomes 3 and 20 and simultaneous interstitial deletion of chromosome 3 in a patient with several minor anomalies of the face and hands. His karyotype is described as 46,XY,t(3;20) (p14.2;p12.2),del(3)(p11-p14.1).