RESUMO
BACKGROUND: Fetoplacental discrepancies occur in approximately 1-2% of analyzed prenatal cases. They are typically due to confined placental mosaicism, where an aberration is observed in the placental cells but not found in the fetal cells. Confined placental mosaicism usually involves aneuploidies and more sparsely structural chromosomal aberrations. To the best of our knowledge, this is the first reported case of a discrepancy in the analyses of chorionic villus sampling and amniocentesis involving two different structural chromosomal aberrations of chromosome 21. CASE PRESENTATION: We report a 33-year-old woman who was referred for a non-invasive prenatal testing due to an increased risk of trisomy 21 gleaned from a combined ultrasound and blood test. The non-invasive prenatal testing showed an increased risk of trisomy 21 with a normalized coverage signal that did not match the fetal cell-free DNA fraction. Rapid aneuploidy detection performed on uncultured chorionic villi indicated mosaicism for trisomy 21. The follow-up analyses revealed discordant chromosomal aberrations: 46,XY,der(21)t(10;21)(p11.21;q10) in the analysis of the chorionic villus sampling and 46,XY, + 21,der(21;21)(q10;q10) in the analysis of the amniocentesis. Thus, the analyses indicated mosaicism for a cell line containing trisomy 21 and a cell line containing a partially duplicated short arm of chromosome 10 in the chorionic villi and complete trisomy 21 resulting from an isochromosome 21 in the amniotic fluid. The analyses of the lymphocytes and the fibroblasts of the woman were normal. CONCLUSIONS: We propose a multiple-step mechanism as a possible theoretical explanation for the formation of these discordant structural chromosomal aberrations in the chorionic villi and amniotic fluid. With this case report, we want to highlight the importance of understanding the possible underlying embryological mechanisms when interpreting results from different prenatal analyses.
RESUMO
BACKGROUND: Small copy number variations confined to the placenta are extremely rare findings in chorionic villus sampling, nonetheless of great clinical importance. To the best of our knowledge, this is the first reported case of confined placental mosaicism for an intragenic Duchenne muscular dystrophy (DMD) gene deletion. CASE PRESENTATION: We describe a pregnant woman where confined placental mosaicism for an intragenic DMD deletion was detected. She was referred for a chorionic villus sampling due to an increased risk of trisomy 21 derived from combined first trimester screening. Rapid aneuploidy detection showed a male fetus with normal results for chromosomes 13, 18 and 21. A chromosomal microarray demonstrated a deletion of exons 61-62 in the DMD gene in approximately 50% of the cells. A follow-up analysis on amniotic cells showed a normal result for the DMD gene. Hence, confined placental mosaicism was confirmed. CONCLUSIONS: We propose tissue specific fragile sites as a possible theoretical mechanism for the formation of submicroscopic copy number variations and highlight that the finding of DMD deletion mosaicism in a chorionic villus sample might be isolated to the placenta. Therefore, confirmation by amniocentesis is of crucial clinical importance to avoid misdiagnosis of the fetus.
RESUMO
The fatty acid (FA) compositions of the diet and diverse tissues of the farmed Siberian sturgeon (Acipenser baerii) were analyzed in detail to assess their nutritional quality. Twelve male fish were sampled for muscle, fat, liver, brain, gill, kidney and gonad and the tissue FA measured by gas-liquid chromatography. The FA profile of the diet diverged from the FA signatures of the tissues, where the sturgeons accumulated particular highly-unsaturated FA (HUFA). They were probably derived from the diet but, as previous studies have shown that fish can also have desaturase enzymes, endogenous synthesis of these FA cannot be excluded. The sturgeon muscle tissue contained HUFA in proportions comparable to those of other fish species that are considered good sources of n-3 polyunsaturated FA. The indices of atherogenicity and thrombogenicity were also within the values considered to be health-promoting.
