Genetic Disease Screening

A well established technique called preimplantation genetic diagnosis (PGD) has been used for several decades to screen embryos for genetic diseases.  Serious single-gene disorders such as sickle-cell anemia can be screened using PGD.  Essentially PGD enables doctors to examine the chromosomes of one cell (called a blastomere) of a 6- to 8-cell embryo. The egg is first fertilized in a laboratory (via IVF) using a sperm and egg from the couple (or from an egg or sperm donor). Next, one cell is removed from this embryo. The chromosomes of this single-cell sample are analyzed using one of several techniques, the most common of which are:

• Fluorescent in situ hybridization (fluorescent in situ hybridization (FISH)),
• Polymerase chain reaction (PCR),
• Single nucleotide polymorphism (SNP) analysis, and
• Comparative genomic hybridization (CGH).  

If one or both parents are carrying a gene for a disease, or suspect they could be, by using PGD, a couple can assess an embryo for a defective gene before it’s implanted into the woman’s uterus to develop.

PGD can screen out over 50 genetic diseases, including:

• Cystic fibrosis
• Down syndrome
• Hemophilia A and B
• Sickle cell anemia (SCA6 form)
• Tay-Sachs disease, Huntington disease
• Alport disease
• Polycystic kidney disease (autosomal dominant and recessive types)
• Becker muscular dystrophy
• Chromosomal translocations
• Congenital adrenal hyperplasia
• Duchenne muscular dystrophy
• Fragile X syndrome
• Gaucher disease
• Neurofibromatosis
• Retinitis pigmentosa
• Spinal muscular atrophy
• Turner syndrome
• X-linked hydrocephaly

Another technique, called MicroSort®, is an exclusive preconception sperm sorting technology that is designed to separate sperm either into those that primarily produce girls or those that primarily produce boys. A recent clinical trial used MicroSort®'s patented technology to investigate the safety and effectiveness of conceiving a child of the indicated gender to either: 1) prevent genetic disease or 2) facilitate family balancing.

The U.S. Food and Drug Administration (FDA) has not reviewed the study's results and has not determined whether MicroSort®is safe and effective. However, while the FDA is reviewing the clinical study data, it has gratned approval to provide continued access to MicroSort® for couples who would like to reduce the inheritability and/or health impact of sex-linked or sex-limited genetic diseases in their children.