中文版
 
Genetic Services

24 Chromosome Microarray

24 Chromosome Microarray analysis is a new, comprehensive chromosomal screening of embryos that examines all chromosomes for abnormalities. GIVF is pleased to now offer patients the state-of-the-art 24 Chromosome Microarray on-site with a fresh IVF cycle.

GIVF's on-site PGD laboratory allows us to offer 24 Chromosome Microarray with the ability to provide a fresh, day 6 embryo transfer after day 5 blastocyst biopsy. In fact, GIVF is the only fertility center in the Washington, DC area offering a day 5 blastocyst biopsy with results available in time for a fresh transfer the following day.

Recent studies have shown that blastocyst or  trophectoderm biopsy likely gives the most accurate PGD results and avoids unclear results associated with day 3 blastomere biopsy. Patients need not worry about their embryo biopsies being sent to an off-site lab to be tested, rather, everything takes place at our fertility center in Fairfax, VA.

What makes 24 Chromosome Microarray different from previous aneuploidy screening?

  • 24 Chromosome Analysis examines all 24 chromosomes (all 22 non-sex chromosomes and the X and Y chromosomes) for abnormalities prior to transfer.
  • This method of testing is more thorough than past methods and allows for the identification of high quality embryos for transfer.
  • Embryos tested with 24 Chromosome Microarray that are determined to be normal are felt to have a much higher chance to result in a successful pregnancy.

24 Chromosome Analysis PGD may be of particular use to patients who have:

  • a history of multiple pregnancy loss,
  • failed IVF attempts despite transfer of good quality embryos, or
  • severe male factor infertility.

To schedule an appointment, click here or call 800.552.4363 or 703.698.7355.

A Brief History of PGD
Preimplantation genetic diagnosis (PGD) of embryos for chromosomal abnormalities was introduced clinically in 1995 to evaluate embryos created by IVF and identify those with the highest potential to produce a pregnancy.  Previous studies have identified chromosomal abnormalities as the main reason for failure of implantation of a transferred embryo or loss of an ongoing pregnancy by spontaneous miscarriage.  Chromosomal abnormalities are found in 50-60% of embryos from women younger than 35 years of age, increasing to 80-90% in women over age 41.

The process of PGD for chromosome defects initially involved removal of one or more cells from an early embryo at the third day after fertilization.  The analysis uses a technique called fluorescent in-situ hybridization (FISH) where small DNA “probes” were used to identify specific chromosomal regions by producing a colored dot on a fixed nucleus from the embryonic cell.  Using PGD/FISH did lead to some improvement in IVF pregnancy rates and a decrease in the rate of spontaneous abortions.  Multiple studies, however, have failed to show an increase in delivery rate after PGD/FISH.  This was felt to be due to several factors including the fact that the current FISH tests could only evaluate 8-12 chromosomes (of the 24 existing chromosomes).  In addition, the early embryo is known to contain abnormal cells that could potentially be eliminated early in development leaving a normal embryo.  However, if the abnormal cell is the one analyzed, the embryo would be designated as abnormal and not used in IVF.  This is called mosaicism and is known to be common in the early human embryo.  Finally, it is believed that removal of even a single cell from the day 3 embryo can affect embryo development.   In summary, the FISH technique was felt to give suboptimal results due to difficulties in interpretation of results, effect of biopsy on embryo development and the presence of confusing mosaicism.

24 Chromosome Microarray
A new method of analysis of the chromosomal status of embryos has been developed over the past three years.  This new test is called 24 Chromosome Microarray, or comprehensive chromosomal screening.  A microarray is a glass slide where hundreds of thousands of DNA sequences are placed and then mixed with labeled DNA obtained from the embryo.  The test analyzes the amount of DNA in the sample relative to a normal male and female control.  By this method one can determine if all of the 23 pairs of chromosomes (not just 8-12) are present in the correct amount.  Embryos tested in this way which are determined to be normal have a much higher chance to result in a successful pregnancy.  In addition, it appears that biopsy of the embryo on day 5 (Blastocyst stage) may give more accurate results which are not as affected by mosaicism as well as not being as detrimental to embryo growth.  This technique is known as trophectoderm biopsy (the trophectoderm is the part of the embryo that will develop into the placenta and fetal membrances).

GIVF is pleased to now offer 24 chromosome microarray analysis for patients undergoing IVF.  In particular, PGD may be valuable for patients with a history of multiple pregnancy loss, failed IVF despite transfer of good quality embryos, or severe male factor infertility.  Due to the fact that we offer this test in our own on-site laboratory, we are able to offer 24 chromosome analysis of trophectoderm samples with the ability to provide a fresh, day 6 embryo transfer.

To schedule an appointment, click here or call 800.552.4363 or 703.698.7355.