Certified Neuroscience Registered Nurse (CNRN) Practice Exam

How is neurofibromatosis typically inherited?

1. Autosomal dominant fashion

2. X-linked recessive fashion

3. Autosomal recessive fashion

4. Spontaneous mutation only

The correct answer is: Autosomal dominant fashion

Neurofibromatosis is typically inherited in an autosomal dominant manner, meaning that only one copy of the mutated gene, inherited from either parent, is sufficient to cause the condition. This type of inheritance allows for the possibility of an affected individual to pass on the disorder to their offspring with a 50% chance for each child. In autosomal dominant disorders like neurofibromatosis, individuals with the condition often show symptoms if they inherit the mutated gene, regardless of whether the other gene copy is healthy or not. This pattern of inheritance explains why neurofibromatosis can appear in multiple generations of a family and can be transmitted from an affected parent to their children. While conditions inherited in X-linked recessive or autosomal recessive fashions involve different mechanisms and inheritance patterns, they do not apply in this context for neurofibromatosis. Additionally, while spontaneous mutations can occur and be the source of new cases, they do not represent the typical inheritance pattern of the disorder across generations.