TRISOMY 8 MOSAICISM: CELL CYCLE KINETICS AND ...

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Cell cycle kinetics (Table 4) was performed to analyze possible growth rate differences between the trisomy 8 and normal cells. Cord blood, transformed blood, and amnion were the only tissues that resulted in successful cell cycle kinetics information. Statistical investigation was done by contingency tables and the Chi-squared goodness of fit test, which in all three cases showed no evidence of a significant difference in cell growth rates between normal and trisomy 8 cell lines. 32
Origin of Trisomy 8 cells DISCUSSION T8m occurs due to mitotic nondisjunction within a normal fetus, therefore introducing a second cell line (James and Jacobs 1996; Karadima et al. 1998; Nicolaidis and Petersen 1998; Webb et al. 1998; Kalousek 1999). The presence of trisomic cells throughout fetal tissues and placental tissues depends directly on the timing of the nondisjunctional event (Webb et al. 1998). The earlier the event in embryonic development, the more tissues will be affected. This includes CPM, which results in a normal fetus and abnormal placenta, due to the nondisjunction occurring in a placental lineage cell. Abnormal placental tissues are correlated to abnormal fetal development, whereas normal to low placental mosaicism supports growth and intrauterine survival of abnormal fetuses (Farra et al. 2000). T8m anomalies, however, are not correlated to the level of mosaicism present within fetal tissues. A similar mosaic constitution within the tissues has been reported for patients, who have had drastic differences in their phenotypes, some being phenotypically normal, where others have severe mental retardation and multiple skeletal anomalies (James and Jacobs 1996; Jordan et al. 1998). The investigation of tissues collected from our patient lead to the determination of an early nondisjunction event since both embryonic and extra-embryonic tissues were mosaic. The embryonic samples, which included umbilical blood, peripheral blood (T-lymphocytes), and umbilical cord each were scored for over 50% trisomy 8 cells in G-banded metaphases, while no trisomic cells were found in the transformed blood (B-lymphoblasts) (Table 1). This difference seen in the level of mosaicism between the 33
Page 1 and 2: TRISOMY 8 MOSAICISM: CELL CYCLE KIN
Page 3 and 4: TABLE OF CONTENTS iii Page Abstract
Page 5 and 6: Trisomy 8 INTRODUCTION Trisomy 8 (T
Page 7 and 8: proliferates and thus mosaicism res
Page 9 and 10: Prenatal Testing Prenatal testing i
Page 11 and 12: DNA undergoing synthesis. Once a sa
Page 13 and 14: centrifugation, aspiration, and fix
Page 15 and 16: insed with water and allowed to air
Page 17 and 18: fixative, and the centrifugation an
Page 19 and 20: FISH slide preparation Day 1 Slides
Page 21 and 22: Case Report RESULTS Amniocentesis,
Page 23 and 24: Figure 2 Trisomy 8 [46, XY, +8] Kar
Page 25 and 26: When comparing embryonic tissues, c
Page 27 and 28: Figure 4 FISH Trisomy 8 [46, XY, +8
Page 29 and 30: There was a notable difference betw
Page 31 and 32: For each tissue the metaphase and i
Page 33 and 34: Figure 6 Second Division - Cell Cyc
Page 35: Table 4. Division Rates for Normal
Page 39 and 40: original finding of La Marche in th
Page 41 and 42: Pallister Killian patients with the
Page 43 and 44: BIBLIOGRAPHY Berry AC, Mutton DE, a
Page 45: Thornberg Reeser SL and Wenger SL.

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