Lack of evidence for monosomy 1p36 in patients with Prader-Willi-like phenotype

Monosomy 1p36 is the most common subtelomeric microdeletion syndrome with an incidence rate estimated to be 1 in 5000 births. A hypothesis of a similarity between patients with 1p36 deletion and those with Prader-Willi syndrome and the existence of two different phenotypes for 1p36 microdeletion has been suggested. The main objective of the present study was to determine the existence of 1p36 microdeletion in a sample of patients with mental retardation, obesity and hyperphagia who tested negative by the methylation test for Prader-Willi syndrome. Sixteen patients (7 females, 9 males), 16-26 years old, were evaluated with high-resolution cytogenetic analysis at 550-850 band levels and with 11 polymorphic microsatellite markers located in the 1p36 region. All patients had normal cytogenetic and molecular results. The results obtained by high-resolution cytogenetic methodology were confirmed by the molecular analyses. We did not detect a 1p36 microdeletion in 16 subjects with the Prader-Willi-like phenotype, which reinforces that no correlation seems to exist between Prader-Willi-like phenotype and the 1p36 microdeletion syndrome

Cytogenetics of human spermatozoa: human/hamster in vitro fertilization technique

A constituição cromossômica do espermatozóide humano pode ser estudada, atualmente, através da técnica de fertilização “in vitro” (FIV), heteróloga, homem/hamster. Essa técnica permite a individualização dos cromossomos do espermatozóide humano, possibilitando a análise de suas anomalias numéricas e estruturais. O aprimoramento dessa técnica estimulou um novo campo de pesquisa na Citogenética Humana e na Genética Clínica. Sua implantação em nosso laboratório na Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, propiciará melhor estimativa da probabilidade de transmissão de anomalias cromossômicas por células da linhagem germinativa de homens em risco genético.The chromosomal constitution of the human spermatozoa can be studied through the heterologous “in vitro” fertilization (FIV) technique (human/hamster). This technique allows the identification of the human sperm chromosomes as well as its numerical and structural analyses. The improvement of this technique has stimulated a new field of research in Human Cytogenetics and in Clinical Genetics. Its implantation in our laboratory at the Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, favor better estimates of the probability of the transmission of chromosomal anomalies by germ cell lines of males at genetic risk

DNA extraction and quantification from touch and scrape preparations obtained from autopsy liver cells

The objective of the present study was to develop a simplified low cost method for the collection and fixation of pediatric autopsy cells and to determine the quantitative and qualitative adequacy of extracted DNA. Touch and scrape preparations of pediatric liver cells were obtained from 15 cadavers at autopsy and fixed in 95% ethanol or 3:1 methanol:acetic acid. Material prepared by each fixation procedure was submitted to DNA extraction with the Wizard® genomic DNA purification kit for DNA quantification and five of the preparations were amplified by multiplex PCR (azoospermia factor genes). The amount of DNA extracted varied from 20 to 8,640 µg, with significant differences between fixation methods. Scrape preparation fixed in 95% ethanol provided larger amount of extracted DNA. However, the mean for all groups was higher than the quantity needed for PCR (50 ng) or Southern blot (500 ng). There were no qualitative differences among the different material and fixatives. The same results were also obtained for glass slides stored at room temperature for 6, 12, 18 and 24 months. We conclude that touch and scrape preparations fixed in 95% ethanol are a good source of DNA and present fewer limitations than cell culture, tissue paraffin embedding or freezing that require sterile material, culture medium, laboratory equipment and trained technicians. In addition, they are more practical and less labor intensive and can be obtained and stored for a long time at low cost

A viable fetus presenting 68,XX[73]/69,XXX[27] triploid mosaicism

Triploidy is common in human pregnancies. It is detected in 1 to 2% of clinically recognized pregnancies and in approximately 15 to 20% of spontaneous abortions produced by chromosome anomalies. We report a premature liveborn girl (30 weeks of gestation) with microcephaly, facial dysmorphism and skeletal abnormalities who died at one day of age due to respiratory failure. The placenta showed partial hydatiform mole. Autopsy revealed no internal malformations. Cytogenetic analysis of 100 metaphases obtained from renal tissue culture revealed a 68,XX[73]/69,XXX[27] karyotype. To our knowledge this is the first report in the literature of 68,XX[73]/69,XXX[27] mosaicism in a liveborn infant.A triploidia é uma anomalia cromossômica comum encontrada em 1 a 2% das gestações clinicamente reconhecidas e em cerca de 15 a 20% dos abortos espontâneos de causa cromossômica. Em aproximadamente 5% dos casos, uma aneuploidia pode estar também associada (Boué et al., 1985). Descrevemos um recém-nascido do sexo feminino, prematuro (30 semanas de idade gestacional), com microcefalia, dismorfias faciais e alterações de membros, que foi a óbito com 1 dia de vida por insuficiência respiratória. O exame anátomo-patológico da placenta revelou alterações compatíveis com degeneração molar. A necrópsia da criança não evidenciou malformações internas. A análise citogenética de 100 metáfases, obtidas a partir de cultura de tecido renal, evidenciou cariótipo 68,XX[73]/69,XXX[27]. Apenas 9 casos de triploidia 68,XX foram descritos anteriormente, sendo 7 em abortos, 1 em feto de 21 semanas e 1 em recém-nascido a termo. Consideramos que este estudo seja o primeiro da literatura relatando a ocorrência de mosaicismo 69,XXX/68,XX em um recém-nascido vivo. Os autores discutem os achados clínicos e os possíveis mecanismos envolvidos nesta aberração cromossômica

A viable fetus presenting 68,XX[73]/69,XXX[27] triploid mosaicism

Triploidy is common in human pregnancies. It is detected in 1 to 2% of clinically recognized pregnancies and in approximately 15 to 20% of spontaneous abortions produced by chromosome anomalies. We report a premature liveborn girl (30 weeks of gestation) with microcephaly, facial dysmorphism and skeletal abnormalities who died at one day of age due to respiratory failure. The placenta showed partial hydatiform mole. Autopsy revealed no internal malformations. Cytogenetic analysis of 100 metaphases obtained from renal tissue culture revealed a 68,XX[73]/69,XXX[27] karyotype. To our knowledge this is the first report in the literature of 68,XX[73]/69,XXX[27] mosaicism in a liveborn infant

A Clinical Study Of 77 Patients With Mucopolysaccharidosis Type Ii

Aim: This study aims to assess the clinical features of 77 South American patients (73 Brazilian) with mucopolysaccharidosis type II (MPS II). Methods: Details of the patients and their disease manifestations were obtained from a review of medical records, interviews with the patients and/or their families, and physical examination of the patients. Results: Mean birth weight was 3360 g, median age at onset of symptoms was 18 months and median age at diagnosis was 6 years. For the whole sample (median age, 8.2 years; range, 2.8-53.0 years), neurological degeneration, typical pebbly skin lesions, seizures and extensive dermal melanocytosis were found in 23.3, 13.0, 13.0 and 1.3% of the cases, respectively. The most frequently reported echocardiogram abnormality was mitral valve regurgitation. Refraction errors were the most common ophthalmological manifestation. The following characteristics were found to be associated with the severe form of MPS II: earlier age at biochemical diagnosis, higher levels of urinary glycosaminoglycans, language development delay, behavioural disturbances, poor school performance and mental retardation. Conclusion: Our results suggest that there is a considerable delay between the onset of signs and symptoms and the diagnosis of MPS II in Brazil (and probably in South America as well), and that many complications of this disease are underdiagnosed and undertreated. 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