What hereditary disease is characterized by blood that does not coagulate?

The hereditary disease characterized by blood that does not coagulate is Hemophilia. This condition is specifically related to deficiencies in certain clotting factors, which are proteins in the blood that contribute to the process of coagulation. When any of these factors are missing or deficient, it leads to excessive bleeding because the blood cannot form clots effectively.

Hemophilia is typically inherited in an X-linked recessive manner, meaning that it predominantly affects males who inherit the affected X chromosome from their mothers. This results in symptoms such as prolonged bleeding, easy bruising, and joint complications from internal bleeding.

In contrast, the other options involve different conditions: Cystic fibrosis is a genetic disorder that primarily affects the lungs and digestive system; Fragile X syndrome is a genetic condition that causes intellectual disability and developmental problems; Down syndrome is a chromosomal condition resulting from an extra copy of chromosome 21, leading to various physical and cognitive impairments. None of these conditions are related to blood coagulation issues like Hemophilia.