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.