Answer:
Cystic fibrosis (CF) is a genetic disorder that primarily affects the lungs, pancreas, and other organs. It is inherited in an autosomal recessive pattern, which means that an individual must inherit two copies of the defective CF gene, one from each parent, to develop the disease. When two carriers of the CF gene have a child, there is a 25% chance that the child will inherit two copies of the defective gene and develop CF.
Given the man's age and diagnosis, it is likely that he has two copies of the defective CF gene and is experiencing symptoms of the disease. As a result, he may be concerned about the possibility of his sister having a child who could also inherit the disease. Encouraging his sister to see a genetic counselor would allow her to understand the potential risks of having a child with CF and explore options for minimizing those risks. The counselor could provide information on genetic testing and reproductive options such as in vitro fertilization (IVF) with preimplantation genetic diagnosis (PGD), which allows for the selection of embryos that do not carry the CF gene.
The American College of Obstetricians and Gynecologists (ACOG) recommends that couples who are carriers of a genetic disorder like CF be referred to a genetic counselor for counseling and testing. This is especially important when one partner has the disorder, as in the case of the man with CF and his sister. A genetic counselor can provide information about the disorder, discuss the risks of having a child with the disorder, and explore reproductive options. With this information, the sister can make an informed decision about whether or not to have a child, and if so, what steps to take to minimize the risk of the child inheriting the disease.
In conclusion, the man with CF's encouragement for his sister to see a genetic counselor is likely driven by his concern for the health of his future niece or nephew. Genetic counseling can provide valuable information and support to couples who are carriers of genetic disorders like CF, allowing them to make informed decisions about their reproductive options.