Final answer:
Some genetic defects trigger disorders caused by errors in chromosome structure, such as Down syndrome due to trisomy 21. Cancer can result from inherited mutations or environmental factors, and genetic diseases are often challenging to treat due to their basis in a patient's DNA.
Step-by-step explanation:
Genetic Disorders Triggered by Chromosomal Defects: Some genetic defects trigger conditions not carried by a single gene but rather by errors in larger parts of a chromosome or in an entire chromosome, often occurring during the formation of eggs or sperm. Having extra chromosomes or damaged chromosomes can cause disorders such as Down syndrome, characterized by a trisomy of chromosome 21, caused by chromosomal nondisjunction during meiosis. The risk of nondisjunction increases with maternal age, especially in women over 36.
Cancer and Genetic Mutations: Complex interactions between carcinogens and an individual's genome can lead to cancer. Not all cancers require an environmental trigger; some stem from replication errors or inherited mutations. Approximately 5 to 10 percent of all cancers involve inherited mutations in genes regulating cell growth or DNA repair. Challenges in Treating Genetic Disorders: Conditions like Severe Combined Immunodeficiency (SCID) illustrate the challenges in treating diseases resulting from genetic mutations, due to the absence of a protein essential for normal bodily functions.
Inheritance and Genetic Diseases: Genetic disorders can be X-linked, Y-linked, autosomal, or due to new mutations. Inherited disorders, like hemophilia or sickle-cell anemia, showcase how genetic makeup can significantly impact an individual's health. Germline mutations can pass down diseases or increase susceptibility to illnesses like breast cancer, while somatic mutations might cause dementia or other neuropathologies.