Which of the following is not categorized as a single-gene disorder?

Edwards syndrome is classified as a chromosomal disorder rather than a single-gene disorder. This condition is caused by the presence of an extra chromosome 18, leading to a range of developmental and physical abnormalities. In contrast, cystic fibrosis, sickle cell disease, and hemophilia are all caused by mutations in a specific gene, making them single-gene disorders.

Cystic fibrosis results from mutations in the CFTR gene, which affects the respiratory and digestive systems. Sickle cell disease is due to a mutation in the HBB gene, leading to the production of abnormal hemoglobin. Hemophilia, which can be either type A or B, is caused by mutations in the F8 or F9 genes, respectively, affecting the blood's ability to clot. These particularities are essential to understanding how different genetic conditions are categorized based on their underlying causes.