Final answer:
Fragile X syndrome is the X-linked disorder characterized by an abnormal number of CGG nucleotide repeats causing inherited mental impairment. It affects the FMR1 gene on the X chromosome and leads to intellectual disability and physical features, more commonly affecting males.
Step-by-step explanation:
The x-linked disorder caused by an abnormal number of repeat sequences in the genome and is the most common cause of inherited mental impairment is Fragile X syndrome. This condition is due to the expansion of the CGG nucleotide repeat affecting the FMR1 gene on the X chromosome. Unlike conditions such as color blindness or Duchenne muscular dystrophy, which are also X-linked disorders, Fragile X syndrome is directly related to the number of repeat sequences and is characterized by intellectual disability, behavioral and learning challenges, and various physical features.
With X-linked recessive inheritance, diseases are more prevalent in males as they have only one X chromosome, while females, with two X chromosomes, are more often carriers without expressing the disease. Females would have to inherit two copies of the recessive gene (one from each parent) to express the trait whereas males only need one from their mother.