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PGD is recommended most frequently for patients with unexplained infertility, recurrent miscarriages, unsuccessful IVF cycles, advanced maternal age, or male factor infertility. The most likely cause is a chromosome abnormality. Chromosome abnormalities include aneuploidy and structural abnormalities. Aneuploidy is the most common chromosomal abnormality. Aneuploidy can occur in both eggs and sperm. Structural abnormalities include translocations, inversions, and deletions. Structural chromosome abnormalities can also be present in eggs and sperm. The transmission of a chromosome abnormality to an embryo can result in a low implantation rate, miscarriage or the birth of a baby with a genetic disorder. Using Fluorescence In Situ Hybridization (FISH), the scientists in our PGD laboratory can identify the absence of these specific genetic disorders in each normal developing embryo. As a result, only those embryos free of genetic disease will be transferred to the patient’s uterus so as to increase the chance of conception and ultimately a healthy baby.
 Recurrent Miscarriage
Fertile couples wih repeated miscarriages should be evaluated for the presence of a chromosomal abnormality. The female or male partner may be a carrier of a balanced translocation or be an aneuploid mosaic.
Unsuccessful IVF cycles
Couples with repeated unsuccessful IVF cycles should be evaluated for the presence of a chromosome abnormality. The female or male partner may be a carrier of a balanced translocation or be an aneuploid mosaic.
Unexplained Infertility
The most probable cause of unexplained infertility or history of habitual miscarriage is a chromosome abnormality. The male OR female partner may be a carrier of a translocation or be an aneuploid mosaic.
Aneuploidy and Advanced Maternal Age
Women of advanced maternal age (> 35) are at a higher risk of producing aneuploid embryos, resulting in implantation failure, a higher risk of miscarriage or the birth of a child with a chromosome abnormality (e.g. Down syndrome). This is due to the fact that all of the woman's eggs are present at birth. Over time, the chromosomes within the egg are less likely to divide properly, resulting in cells with too many or too few chromosomes. Aneuploidy is also believed to be a major reason for the decrease of fertility with age. Prior to attempting a pregnancy, women in this age group may wish to talk with their physician or a medical geneticist about their chances of having a child with a genetic disease and how PGD may be able to help.
Table: Women of advanced maternal age are at increased risk of producing an embryo affected with a genetic disease.
Maternal Age |
Trisomy 21 |
Trisomy 18 |
Trisomy 13 |
15 - 19 |
1:1250 |
1:17000 |
1:33000 |
20 - 24 |
1:1400 |
1:14000 |
1:25000 |
25 - 29 |
1:1100 |
1:11000 |
1:20000 |
30 - 34 |
1:700 |
1:7100 |
1:14000 |
35 - 39 |
1:200 |
1:2400 |
1:4800 |
40 - 44 |
1:60 |
1:700 |
1:1600 |
Male Factor Infertility
Approximately one-half of all infertility is caused by sperm abnormalities. Many sperm disorders are due to a chromosome abnormality such as aneuploidy or a structural chromosome abnormality. Men carrying a balanced translocation chromosome are at risk of producing sperm with a structural chromosome abnormality. Research has shown that approximately 3 to 8% of sperm from normal, fertile men are aneuploid. In contrast, between 27 and 74% of sperm from men with severe infertility (i.e. low sperm count, poor morphology, poor motility) is aneuploid. Couples with infertility due to male factor, should consider chromosome analysis on the males sperm prior to IVF.
Y Chromosome Deletions and Infertility
Y chromosome deletions are found in approximately 5 to 20% of males with a very low sperm count. These deletions appear to impair normal sperm development. While these deletions do not appear to cause any genetic disease, they appear to decrease the chance of men with a low sperm count to successfully fertilize eggs in a normal way.
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