Final answer:
PNPs would likely advise individuals with Marfan Syndrome, an autosomal dominant disorder affecting connective tissue, to avoid contact sports due to the risk of severe cardiovascular complications.
Step-by-step explanation:
The genetic disorder amongst the provided options that a Pediatric Nurse Practitioner (PNP) would likely counsel about avoiding contact sports is Marfan Syndrome.
Marfan Syndrome is an autosomal dominant disorder characterized by defects in connective tissue, which can lead to abnormalities in the skeletal system, cardiovascular system, eyes, and skin. Since Marfan Syndrome can cause cardiovascular abnormalities, including aortic enlargement, individuals with this condition may be at higher risk of life-threatening complications if they sustain trauma or injury to the chest. Hence, avoidance of contact sports is often recommended to minimize the risk of damage to the aorta or other weakened tissues.