Question

Hemophilia is a rare bleeding disease that is carried on the X-chromosome. More than 400,000 people worldwide live with this disease, 20,000 of those within the United States. It is commonly called the “royal disease” because Queen Victoria was known to be a carrier of the disease and passed the gene to other members of the royal family. If a healthy individual who does not have hemophilia gets a small cut on their arm, it takes 2-8 minutes on average for clotting to occur and for the bleeding to stop. People suffering from hemophilia lack an essential blood-clotting protein in their blood plasma. If they get cut, it can take 30 minutes to 22 hours for the bleeding to stop. Excessive bleeding is a constant danger to individuals with hemophilia.

Answer 1

Hemophilia is a genetic disorder that affects blood clotting, primarily in males due to the X chromosome linkage, with types A and B being the most common. Females require two mutated X chromosomes to present with the disease.

Step-by-step explanation:

Hemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting, which is usually caused by the absence of certain clotting factors in the blood. The two most common forms are hemophilia A, caused by the lack of factor VIII, and hemophilia B, due to the deficiency of factor IX. Both are linked to the X chromosome, causing a higher prevalence in males, who have only one X chromosome (XY), over females, who have two (XX). Hemophilia C involves an autosomal chromosome and is not sex-linked.

When it comes to the rare instances of females being affected, they would require two mutated X chromosomes to exhibit the disease (answer a). Men, having only one X chromosome, will express hemophilia if the X chromosome they inherit has the mutation, hence the condition being more common in males. Treatments for hemophilia often involve regular infusions of clotting factors isolated from healthy donors, and in the future, genetic therapy may become available.

Historically, hemophilia has been referred to as the “royal disease” due to its presence in European royal families, most notably passed by Queen Victoria to various descendants. Patients with hemophilia experience prolonged bleeding from minor injuries and are at risk of serious bleeding episodes.