Finding hope with genetic screening of parents
The American College of Obstetrics and Gynecology has recently recommended genetic screening of parents. The purpose of this testing is to identify couples who are carriers of a variety of conditions that could affect their children. Testing potential parents for genetic diseases is not a novel concept. However, recent advances in technology have made testing simple, painless and affordable.
Exploring the purpose of genetic screening of parents
Carriers of genetic diseases do not actually have the disorder themselves. Rather one of their genes has a mutation, genetic change, associated with the disorder. The concern is that carriers can unknowingly pass this abnormal gene on to their children. The most common genetic disorders, such as sickle cell, Tay Sachs Disease and cystic fibrosis are autosomal recessive diseases. In order to actually have such a disease, a person needs to inherit two abnormal genes, one from each parent.
If both parents are carriers, each embryo has a 25% chance of inheriting two normal genes. There is also a 25% chance of inheriting 2 defective genes (these children will have the disease). There is a 50% chance of inheriting 1 normal gene and 1 defective gene (these children will be carriers).
Stopping the cycle
Genetic screening of parents is the only way to know if children have an increased risk of inheriting a disorder. Due to tremendous advances in science, two new types of genetic testing are now available. One involves the collection of saliva from each partner. Labs can screen each sample for over 109 different autosomal recessive genetic disorders for a reasonable fee.
If only one partner carries the gene for an autosomal recessive disorder, there is no chance that the couple’s children can actually have the disease in question. The worst outcome possible would be that a child could be a carrier of the abnormal gene – just like the affected parent.
The other type of test looks at pieces of genes, rather than whole genes or chromosomes. Through the testing of tissue from either a cheek swab or blood from each partner, labs can review 200-300,000 small DNA fragments representing pieces of each known gene.
When an embryo comes from in vitro fertilization, the DNA from each embryo can be matched to the samples from the parents. Not only can this testing determine whether each embryo has the normal number of chromosomes, but we can identify the source of any identified genetic abnormality. In other words, in the event that an embryo turns out to be chromosomally abnormal, this testing can determine whether the abnormality came from the egg or from the sperm. This is very helpful in cases of recurrent miscarriage or in cases of repetitive in vitro fertilization failure.
These two exciting new technologies represent a major advance in the field of genetics. They offer our patients even greater hope for achieving their dream of a healthy family. Contact us to learn more about genetic screening for parents.