Cockayne Syndrome (CS) is a rare genetic disorder with an autosomal recessive pattern of inheritance. Understanding the genetics behind CS is essential for accurate diagnosis, assessing the risk of recurrence in families, and making informed decisions regarding family planning. The condition is primarily caused by mutations in one of two genes: ERCC6 (also known as CSB) or ERCC8 (also known as CSA). These genes provide instructions for making proteins that are essential for repairing damaged DNA, particularly damage caused by ultraviolet (UV) light.
In an autosomal recessive disorder like Cockayne Syndrome, an individual must inherit two mutated copies of the responsible gene—one from each parent—to develop the condition. The parents of an affected individual are typically carriers of the disease; they each have one mutated copy of the gene and one normal copy. Carriers generally do not show any symptoms of the disorder because the single normal copy of the gene is sufficient to maintain adequate DNA repair function.
When two carriers have a child, there is a 25% chance with each pregnancy that the child will inherit both mutated genes and be affected by Cockayne Syndrome. There is a 50% chance that the child will inherit one mutated gene and be a carrier like the parents, and a 25% chance that the child will inherit two normal genes and be neither affected nor a carrier. These probabilities remain the same for each subsequent pregnancy.
For families with a history of Cockayne Syndrome, genetic counseling is highly recommended. A genetic counselor can provide detailed information about the inheritance pattern, arrange for genetic testing to identify the specific mutations in the family, and discuss options for family planning. Carrier testing is available for at-risk relatives, and prenatal diagnosis or preimplantation genetic diagnosis (PGD) can be offered to couples who are known carriers. These tools empower families to make informed choices about their reproductive future. Patients and families should consult with a healthcare provider or a certified genetic counselor to explore these options.