PubMed · 7103003
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S C Finley. 1982. Genetic counseling.. https://pubmed.ncbi.nlm.nih.gov/7103003/
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Tetrasomy 8p is a rare chromosomal disorder that has only been detected in a mosaic form. At the present time, 11 cases have been reported; their phenotype included agenesis of the corpus callosum, enlarged ventricles, minor facial dysmorphism, rib and vertebral anomalies, and mild to moderate developmental delay. To the best of our knowledge, tetrasomy 8p has never been prenatally diagnosed. This 43-year-old woman was referred for amniocentesis at 20 weeks' gestation because of advanced maternal age. Amniotic fluid cells were cultured according to standard techniques by the in situ method. A supernumerary chromosomal marker was detected in a single clone of cultured amniotic cells and interpreted by RHG banding as an isochromosome of the short arm of chromosome 8 (i(8p)). The ultrasound investigation at 27 weeks gestation revealed enlarged ventricles and agenesis of the corpus callosum, which were confirmed at fetal autopsy after medical termination of the pregnancy. Chromosomal analyses, including RHG banding and FISH, of several tissues showed different levels of i(8p) mosaicism. Whereas no i(8p) was detected on cytotrophoblast nor additional amniotic fluid cells, 97% and 30% of cells from long-term cultures of placenta and lymphocytes, respectively, had the i(8p). Using DNA markers, the isochromosome 8p was interpreted as the result of a prezygotic event during maternal meiosis. Our findings suggest that the i(8p) is the subject of tissue selection. Tetrasomy 8p might be underdiagnosed during pregnancy; therefore, karyotyping on a fetal blood sample following detection of agenesis of the corpus callosum when no chromosomal abnormality has been found on the amniotic fluid cell cultures should be discussed with the parents.
INTRODUCTION: Each of the processes involved in the development of the central nervous system is under genetic control and some mutations are responsible for severe malformations. For example, holoprosencephaly is associated with HPE genes, hydrocephalus with L1-CAM and lissencephaly with LIS-1. DISCUSSION: Molecular genetics has brought new insights into the etiology and pathogenesis of nervous system malformations and has provided new tools for accurate prenatal diagnosis.
OBJECTIVES: To assess amniotic fluid (AF) HIV contamination as a marker of intrauterine HIV infection and to evaluate amniocentesis as a risk factor for vertical HIV transmission when the mother was under antiretroviral treatment. STUDY DESIGN: Three hundred and sixty-six HIV pregnant women were included in the study. AF was obtained from three groups of patients: (a) genetic amniocentesis before 1997 (n=11); (b) amniocentesis a few days before the delivery day (n=18); and (c) AF collected on delivery (n=38). An univariate study was conducted to analyze amniocentesis as a risk factor of HIV transmission (groups a and b). Groups b and c were recruited after 1997; these patients were under combined antiretroviral treatment, they were studied to relate AF HIV contamination with fetal infection and maternal blood viral load at delivery (n=56). RESULTS: From 1984 to 1996, before antiretroviral therapy use in HIV pregnant women, transmission rate was 17%. In the group of patients who underwent genetic amniocentesis (group a) it was 30% (3/10) versus 16.2% (40/247) for patients without amniocentesis. Between 1997 and 2000 transmission rate was 3%. In group b it was 0% (0/18) when amniocentesis was done versus 3.7% (3/81) if no amniocentesis was done (no statistical differences). AF virus was undetectable in all samples (n=56) and no newborn infection was observed after the follow up. CONCLUSIONS: Amniotic fluid virus load was undetectable when maternal antiretroviral therapy was used, even if the virus was detectable in maternal blood samples. This finding raises the possibility to perform amniocentesis, when it is indicated, to provide the mother with an adequate antiretroviral treatment.