Monosomic/Single Gene Disorders (PGT-M) &
Chromosomal Structural Rearrangements (PGT-SR)
X-linked disorders are so named because they are caused by genes located on the X chromosome. Females have two copies of the X chromosome, while males have one X and one Y chromosome. The single copy of the X chromosome puts males at an increased risk of having X-linked disorders. A carrier mother has a 50% chance of passing on her mutated copy of the gene to her children. Carrier females typically exhibit mild symptoms or none at all because they still possess one healthy copy on their other X chromosome. However, all sons who inherit the mutated gene will be affected with the disease because they have no healthy copies to compensate.
The genetics of cancer is a complicated story. Through widespread efforts of cancer researchers around the world, our understanding of the role of genetics in cancer has developed tremendously. It is important to understand that cancer is a multi-factorial disease, where both genetic and environmental factors contribute to risk on an individual basis. A person who inherits a cancer-risk gene does not necessarily show symptoms or ever develop cancer, but they can still pass this gene to their children. Although not all forms of cancer are inherited, studies have identified over 50 hereditary cancer syndromes with strong evidence for a genetic link.
Some genetic diseases are more common in particular ethnic groups compared to the general population. This is because people in the same ethnic group share some genetic information inherited from common ancestors. Common examples include: