Preimplantation genetic diagnosis PGD
A single-gene disease is a hereditary disease caused by a single defective gene, which can be caused by inheritance from parents or during the development of the germ cells themselves. Unifactory diseases are the main source of various problems, including birth defects, early death and disability, and have a direct impact on the psychology and society of the entire family.
The Millennium Reproductive Center has introduced pre-implantation genetic diagnosis (PGD) technology, which brings good news to high-risk patients with genetically defective genes. This technique can be used for all single-gene defects (autosomal recessive, autosomal Sexual and sexual chromosome structural abnormalities are tested.
Therefore, embryo chromosomal screening of single-gene disorders through pre-pregnancy or during pregnancy can help parents have healthy children, which is an effective way to help parents dream and prevent chromosomal abnormalities in the next generation of children.
If both parents carry a mutated gene, their child has a quarter of the chance to have a genetic disease.
Using a known genetic disease reference, you can look at the chromosome to which the gene is attached and determine which chromosomal abnormality carries the DNA.
Then by examining the genetics, scientists can determine whether each embryo's genetic DNA fragment carries a mutated gene or a normal copy using conventional molecular genetic techniques, using SANGER sequencing and next-generation gene sequencing (NGS) to detect mutant genes.
Whether the embryo inherits a copy of the mutated gene as a vector like their parents, or if it has two copies of the mutated gene, it will develop the disease. If the mutant gene is not copied, the embryo may be unaffected and a good candidate embryo that is transferred to the female uterus.
Preimplantation genetic diagnosis (PGD) relies on the high sensitivity, specificity, and reliability of molecular genetics to screen for defective genes in maternal and embryonic.
This genetic information provides direct evidence for the onset of maternal monogenic diseases and prevents the transmission of genes for monogenic diseases to their offspring.
Each case for PGD diagnosis will be discussed and evaluated by laboratory staff and appropriate techniques will be recommended to the patient. Our center has two technologies to choose from:
1) Short tandem repeat STR method – based on linkage analysis.
This technique uses a site-specific region on the DNA as a sample for comparison. Human genomic DNA has 3 x 109 bp, 10% of which are tandem repeats, called satellite DNA. According to the length of the repeating unit, it can be divided into large satellites, medium satellites, small satellites and microsatellites. The STR is a microsatellite containing units of 2 to 13 nucleotides that are repeated hundreds of times in a DNA strand. The STR method measures and analyzes the exact number of repeating units.
2) Karyotype positioning PGD (Karyomapping)
(Analysis of whether the embryo inherits genetic traits by analyzing the DNA of one's own and relatives. The principle is to compare the DNA samples of the embryo with the parents and close relatives, and to map the genetic disease genes by plotting the genetic map of the family. Look for unique genetic markers, just like fingerprints. These markers can be used to find normal embryos, and it can be confirmed that the fragment of the genetic defect gene is from which parent, so that parents can detect the abnormality of the embryo when implanting money in the embryo. situation.
This technique uses single nucleotide polymorphisms (SNPs) as detectors. There are approximately 10 million SNPs in the human genome. This technique is also based on the Linked Analysis Model (STR). The advantage of this technique is that it requires less analysis time, more detectors, reduced alleles and a wider range of genetic disease exits, and automated opportunities (general testing).
Why does the Millennium Reproductive Center perform biopsy on embryos on day 5/6?
Day 5/Day 6 Embryo (blastocyst stage) is an already developed embryo, so biopsy reduces damage to the embryo.
We can also get more DNA and fewer mosaics from the 5th/6th day embryo biopsy. The latest data demonstrates that biopsy on day 5/day 6 yields a higher success rate than biopsy on day 3.