Tshr Intronic Polymorphisms (rs179247 And Rs12885526) And Their Role In The Susceptibility Of The Brazilian Population To Graves' Disease And Graves' Ophthalmopathy.

Intronic thyroid-stimulating hormone receptor polymorphisms have been associated with the risk for both Graves' disease and Graves' ophthalmopathy, but results have been inconsistent among different populations. We aimed to investigate the influence of thyroid-stimulating hormone receptor intronic polymorphisms in a large well-characterized population of GD patients. We studied 279 Graves' disease patients (231 females and 48 males, 39.80 ± 11.69 years old), including 144 with Graves' ophthalmopathy, matched to 296 healthy control individuals. Thyroid-stimulating hormone receptor genotypes of rs179247 and rs12885526 were determined by Real Time PCR TaqMan(®) SNP Genotyping. A multivariate analysis showed that the inheritance of the thyroid-stimulating hormone receptor AA genotype for rs179247 increased the risk for Graves' disease (OR = 2.821; 95 % CI 1.595-4.990; p = 0.0004), whereas the thyroid-stimulating hormone receptor GG genotype for rs12885526 increased the risk for Graves' ophthalmopathy (OR = 2.940; 95 % CI 1.320-6.548; p = 0.0083). Individuals with Graves' ophthalmopathy also presented lower mean thyrotropin receptor antibodies levels (96.3 ± 143.9 U/L) than individuals without Graves' ophthalmopathy (98.3 ± 201.9 U/L). We did not find any association between the investigated polymorphisms and patients clinical features or outcome. We demonstrate that thyroid-stimulating hormone receptor intronic polymorphisms are associated with the susceptibility to Graves' disease and Graves' ophthalmopathy in the Brazilian population, but do not appear to influence the disease course.

Frequency of the different mutations causing spinocerebellar ataxia (SCA1, SCA2, MJD/SCA3 and DRPLA) in a large group of Brazilian patients

Spinocerebellar ataxia type 1 (SCA1), spinocerebellar ataxia type 2 (SCA2) and Machado-Joseph disease or spinocerebellar ataxia type 3 (MJD/SCA3) are three distinctive forms of autosomal dominant spinocerebellar ataxia (SCA) caused by expansions of an unstable CAG repeat localized in the coding region of the causative genes. Another related disease, dentatorubropallidoluysian atrophy (DRPLA) is also caused by an unstable triplet repeat and can present as SCA in late onset patients. We investigated the frequency of the SCA1, SCA2, MJD/SCA3 and DRPLA mutations in 328 Brazilian patients with SCA, belonging to 90 unrelated families with various patterns of inheritance and originating in different geographic regions of Brazil. We found mutations in 35 families (39%), 32 of them with a clear autosomal dominant inheritance. The frequency of the SCA1 mutation was 3% of all patients; and 6 % in the dominantly inherited SCAs. We identified the SCA2 mutation in 6% of all families and in 9% of the families with autosomal dominant inheritance. The MJD/SCA3 mutation was detected in 30 % of all patients; and in the 44% of the dominantly inherited cases. We found no DRPLA mutation. In addition, we observed variability in the frequency of the different mutations according to geographic origin of the patients, which is probably related to the distinct colonization of different parts of Brazil. These results suggest that SCA may be occasionally caused by the SCA1 and SCA2 mutations in the Brazilian population, and that the MJD/SCA3 mutation is the most common cause of dominantly inherited SCA in Brazil.

Molecular diagnosis of Huntington disease in Brazilian patients

Huntington disease (HD) is a progressive neurodegenerative disorder with autosomal dominant inheritance, characterized by choreiform movements and cognitive impairment. Onset of symptoms is around 40 years of age and progression to death occurs in approximately 10 to 15 years from the time of disease onset. HD is associated with an unstable CAG repeat expansion at the 5' and of the IT15 gene. We have genotyped the CAG repeat in the IT15 gene in 44 Brazilian individuals (42 patients and 2 unaffected family members) belonging to 34 unrelated families thought to segregate HD. We found one expanded CAG allele in 32 individuals (76%) belonging to 25 unrelated families. In these HD patients, expanded alleles varied from 43 to 73 CAG units and normal alleles varied from 18 to 26 CAGs. A significant negative correlation between age at onset of symptoms and size of the expanded CAG allele was found (r=0.6; p=0.0001); however, the size of the expanded CAG repeat could explain only about 40% of the variability in age at onset (r2=0.4). In addition, we genotyped 25 unrelated control individuals (total of 50 alleles) and found normal CAG repeats varying from 16 to 33 units. The percentage of heterozigocity of the normal allele in the control population was 88%. In conclusion, our results showed that not all patients with the HD phenotype carried the expansion at the IT15 gene. Furthermore, molecular diagnosis was possible in all individuals, since no alleles of intermediate size were found. Therefore, molecular confirmation of the clinical diagnosis in HD should be sought in all suspected patients, making it possible for adequate genetic counseling.

Epilepsias parciais familiares

OBJECTIVE: To investigate the clinical and genetic characteristics of familial partial epilepsies. METHOD: Family history of seizures was questioned in all patients followed in our epilepsy clinics, from October 1997 to December 1998. Those with positive family history were further investigated and detailed pedigrees were obtained. All possibly affected individuals available underwent clinical evaluation. Seizures and epilepsy syndromes were classified according to the ILAE recommendations. Whenever possible, EEG and MRI were performed. RESULTS: Positive family history was identified in 32 unrelated patients. A total of 213 possibly affected individuals were identified, 161 of whom have been evaluated. The number of affected subjects per family ranged from two to 23. Temporal lobe epilepsy (TLE) was identified in 22 families (68%), frontal lobe epilepsy in one family (3%), partial epilepsy with centrotemporal spikes in five families (15%), and other benign partial epilepsies of childhood in four families (12%). Most of the affected individuals in the TLE families (69%) had clinical and/or EEG characteristics of typical TLE. However, the severity of epilepsy was variable, with 76% of patients with spontaneous seizure remission or good control with medication and 24% with refractory seizures, including 7 patients that underwent surgical treatment. In the other 10 families, we identified 39 possibly affected subjects, 23 of whom were evaluated. All had good seizure control (with or without medication) except for one patient with frontal lobe epilepsy. Pedigree analysis suggested autosomal dominant inheritance with incomplete penetrance in all families. CONCLUSION: Family history of seizures is frequent among patients with partial epilepsies. The majority of our families had TLE and its expression was not different from that observed in sporadic cases. The identification of genes involved in partial epilepsies may be usefull in classification of syndromes, to stablish prognosis and optimal treatment.

Análise bayesiana do modelo de herança monogênica no melhoramento vegetal: um exemplo com abobrinha

A common breeding strategy is to carry out basic studies to investigate the hypothesis of a single gene controlling the trait (major gene) with or without polygenes of minor effect. In this study we used Bayesian inference to fit genetic additive-dominance models of inheritance to plant breeding experiments with multiple generations. Normal densities with different means, according to the major gene genotype, were considered in a linear model in which the design matrix of the genetic effects had unknown coefficients (which were estimated in individual basis). An actual data set from an inheritance study of partenocarpy in zucchini (Cucurbita pepo L.) was used for illustration. Model fitting included posterior probabilities for all individual genotypes. Analysis agrees with results in the literature but this approach was far more efficient than previous alternatives assuming that design matrix was known for the generations. Partenocarpy in zucchini is controlled by a major gene with important additive effect and partial dominance.