Increased TERC gene copy number in amniocytes from fetuses with trisomy 18 or a sex chromosome aneuploidy

Objective: Individuals with chromosomal aneuploidies tend to develop malignancies. Telomerase is an enzyme complex that lengthens telomeres and has enhanced expression in numerous malignancies; one of its components is encoded by the TERC gene. In this study, we evaluated the TERC gene copy number in amniocytes from fetuses with aneuploidy, other than trisomy-21. Methods: In this prospective, basic research study, fluorescence in situ hybridization (FISH) for the TERC gene (3q26) was applied to amniocytes retrieved from 14 fetuses with various aneuploidies and from a control group of 6 fetuses with a normal karyotype, to determine the TERC gene copy number. Results: The percentage of cells with more than two copies of the TERC gene was lowest in the control group (x3. =1.2. ±. 0.4%; x4. =. 0. ±. 0%), higher in the sex chromosome aneuploidies (x3. =. 4. ±. 3%; x4. =. 0.7. ±. 0.95%) and even higher in trisomy 18 (x3. =. 10.6. ±. 2.3; x4. =. 4.6. ±. 1.8). The differences were statistically significant (P. <. 0.05). Conclusion: The TERC gene copy number is increased in aneuploid amniocytes, which demonstrates their genetic instability and is presumably related to their tendency to develop malignancies.