Which of the following represents an example of an X-linked dominant disorder?

Fragile-X syndrome is an example of an X-linked dominant disorder, which means that the gene responsible for the disorder is located on the X chromosome and that only one copy of the mutated gene is sufficient to present with the disorder in both males and females. Since females have two X chromosomes, they can be affected even if only one of their X chromosomes carries the mutation. This is in contrast to X-linked recessive disorders, where typically males are more frequently affected because they have only one X chromosome.

Fragile-X syndrome specifically results from a mutation in the FMR1 gene, which leads to developmental issues, intellectual disabilities, and various behavioral challenges. The inheritance pattern seen in Fragile-X syndrome is indicative of X-linked dominant disorders as affected individuals can have an affected parent. In this context, it’s crucial to recognize that the disorder can be passed from an affected mother to her children regardless of their gender, resulting in various levels of expression in both males and females.

Other options to consider involve different inheritance patterns. Wiskott-Aldrich syndrome is X-linked recessive, Prader-Willi syndrome is associated with imprinting on chromosome 15 and not linked to sex chromosomes, and Becker muscular dystrophy is also X-linked recessive