Frequency of spinocerebellar ataxia type 1, dentatorubropallidoluysian atrophy, and Machado-Joseph disease mutations in a large group of spinocerebellar ataxia patients.

The spinocerebellar ataxias (SCAs) are a heterogeneous group of neurodegenerative disorders varying in both clinical manifestations and mode of inheritance. Six different genes causing autosomal dominant SCA are mapped: SCA1, SCA2, Machado-Joseph disease (MJD)/SCA3, SCA4, SCA5, and dentatorubropallidoluysian atrophy (DRPLA). Expansions of an unstable trinucleotide CAG repeat cause three of these disorders: SCA type 1 (SCA1), MJD, and DRPLA. We determine the frequency of the SCA1, DRPLA, and MJD mutations in a large group of unrelated SCA patients with various patterns of inheritance and different ethnic backgrounds. We studied 92 unrelated SCA patients. The frequency of the SCA1 mutation was 3% in the overall patient group and 10% in the non-Portuguese dominantly inherited SCA subgroup. We found that DRPLA mutation in only one Japanese patient, who was previously diagnosed with this disease. We identified the MJD mutation in 41% of the overall patient group, which included 38 autosomal dominant kindreds of Portuguese origin; the frequency of the MJD mutation among the non-Portuguese dominantly inherited cases was 17%. These results suggest that SCA may be occasionally caused by the SCA1 mutation and rarely caused by the DRPLA mutation and that, to date, the MJD mutation seems to be the most common cause of dominantly inherited SCA. Finally, our results suggest that recessively inherited cases of SCA are not caused by the known trinucleotide repeat expansions.

True agonadism: report of a case analyzed with Y-specific DNA probes.

We report on a 5-year-old girl with a male karyotype (46,XY), severe psychomotor and physical retardation, minor anomalies, and female external genitalia with a blindly ending vagina. She has normal adrenal function, prepubertal serum gonadotropin and testosterone levels, which did not rise after hCG stimulation. On abdominal exploration no gonads were found, and only mesonephric and Müllerian remnants. She was HY positive, and no deletion was detected in the Y chromosome using 5 different probes. Although a genetic defect is not excluded, pregnancy complications suggest an environmental insult to the developing testes.

Familial glioblastoma.

The authors describe a family with three members affected by glioblastoma. The proband patient, a 7 year-old girl, developed a rare complication, a pulmonary metastasis. Chromosomal analysis of her peripheral blood lymphocytes showed a normal karyotype (46, XX), without structural abnormalities. Cytogenetic study of the tumor cells disclosed several abnormalities: 46, XX, 7q-/46, XX, -2, 4p-, 7p-, +15/46, XX. Some aspects about genetics of glial neoplasms are discussed.

Clinical and molecular characteristics of a Brazilian family with spinocerebellar ataxia type 1.

The spinocerebellar ataxias (SCAs) are a clinically and genetically heterogeneous group of late onset neurodegenerative disorders. To date, seven different genes causing autosomal dominant SCA have been mapped: SCA1, SCA2, Machado-Joseph disease (MJD)SCA3, SCA4, SCA5, SCA7 and dentatorubropallidoluysian atrophy (DRPLA). Expansions of an unstable trinucleotide CAG repeat cause three of these disorders: SCA1, MJD/SCA3 and DRPLA. We studied one Brazilian family segregating an autosomal dominant type of SCA. A total of ten individuals were examined and tested for the presence of the SCA1, MJD and DRPLA mutations. Three individuals, one male, and two females, were considered affected based on neurological examination; ages at onset were 32, 36 and 41 years. The first complaint in all three patients was gait ataxia which progressed slowly over the years. Six individuals showed one allele containing an expanded CAG repeat in the SCA1 gene. The mean size of the expanded allele was 48.2 CAG units. Instability of the expanded CAG tract was seen in the two transmissions that were observed in this family. In both occasions there was a contraction of the CAG tract. Our study demonstrates that SCA1 occurs in the Brazilian population. In addition, our results stress the importance of molecular studies in the confirmation of diagnosis and for pre-symptomatic testing in SCAs.

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.

Nuchal translucency: an ultrasound marker for fetal chromosomal abnormalities.

CONTEXT: The literature shows an association between several ultrasound markers and chromosome abnormality. Among these, measurement of nuchal translucency has been indicated as a screening method for aneuploidy. The trisomy of chromosome 21 has been most evaluated. OBJECTIVE: To define the best fixed cutoff point for nuchal translucency, with the assistance of the ROC curve, and its accuracy in screening all fetal aneuploidy and trisomy 21 in a South American population. TYPE OF STUDY: Validation of a diagnostic test. SETTING: This study was carried out at the State University of Campinas, Campinas, Brazil. PARTICIPANTS: 230 patients examined by ultrasound at two tertiary-level private centers, at 10 to 14 weeks of gestation. DIAGNOSTIC TEST: The participants consisted of all those patients who had undergone ultrasound imaging at 10 to 14 weeks of gestation to measure nuchal translucency and who had had the fetal or neonatal karyotype identified. MAIN MEASUREMENTS: Maternal age, gestational age, nuchal translucency measurement, fetal or neonatal karyotype. RESULTS: Prevalence of chromosomal defects - 10 %; mean age - 35.8 years; mean gestational age - 12 weeks and 2 days; nuchal translucency (NT) thickness - 2.18 mm. The best balance between sensitivity and specificity were values that were equal to or higher than 2.5 mm for overall chromosomal abnormalities as well as for the isolated trisomy 21. The sensitivity for overall chromosomal abnormalities and trisomy 21 were 69.5 % and 75 %, respectively, and the positive likelihood ratios were 5.5 and 5.0, respectively. CONCLUSION: The measurement of nuchal translucency was found to be fairly accurate as an ultrasound marker for fetal abnormalities and measurements equal to or higher than 2.5 mm were the best fixed cutoff points.

[Thalassemia and Hansen's disease]. / Talassemia e hanseníase.

The beta-thalassemia trait was investigated among 165 Brazilians who were unmixed Italian descendants (80 Virchowian patients and 85 normal controls, composed of universitary students). The frequency of the beta-thalassemia trait was 6.25% among the Virchowian patients and 5.88% in the control group. In spite of the similar geographical distribution of both hanseniasis and the gene for beta-thalassemia in Asia, the present data does not support the hypothesis that hanseniasis might have contributed to maintain high prevalence of this allele by selection favouring beta-thalassemia trait.

Avaliacao do peso e da estatura fetal pelo ultra-som, utilizando-se varios parametros. / Evaluation of fetal weight and length as measured by ultrasound according to different parameters

Em 34 mulheres gravidas a termo mediu-se, pelo ultra-som, o diametro biparietal fetal, o diametro transverso toracico fetal e o diametro abdominal fetal, com um intervalo maximo de 12h entre essas medicoes e o parto cesareo eletivo. Foram obtidas as estimativas do peso e da estatura fetal por analise de regressao multipla utilizando-se como variaveis independentes o diametro biparietal fetal, o diametro transverso do torax do feto e o diametro abdominal fetal. O mais alto coeficiente de correlacao foi entre o diametro abdominal e o peso fetal. Tais estimativas sao de extrema importancia para a decisao obstetrica e para o prognostico fetal

Atypical pseudocholinesterase in Northeastern Brazilian caucasoids.

A frequencia de gene responsavel pseudocolinesterase atipica foi estimada em 2,73% entre 110 caucasoides do Nordeste brasileiro. Essa prevelencia e muito semelhante a observada em caucasoides do Sudeste do Brasil (2,59%). Os dados apresentados apoiam a hipotese de que a frequencia do alelo E1a entre os caucasoidess que participaram da formacao da populacao tri-hibrida do Nordeste brasileiro era mais alta do que a comumente observadas entre europeus

Diagnóstico pré-natal por punçäo da vilosidade coriônica / Prenatal diagnosis by chorionic villus sampling

Resultado de 129 punçöes da vilosidade coriônica para diagnóstico pré-natal no primeiro trimestre de gestaçäo. Os métodos de rotina par preparaçäo direta, preparaçäo de 24 horas e cultura de longa duraçäo, bem como as indicaçöes säo descritos detalhadamente. Tendo em vista a precocidade desse exame e alto sucesso de técnica (97,4%), pode-se concluir pela sua aceitabilidade como método complementar de diagnóstico genético pré-natal