Final answer:
Genetic disorders can fall into different age categories based on the underlying causes. Mutations in specific genes can lead to early onset genetic disorders, while chromosomal disorders are more likely to occur as women age.
Step-by-step explanation:
Several genetic disorders are categorized into different age groups because of the underlying causes and mechanisms involved in their development. One factor is the presence of mutations in specific genes, which can lead to genetic disorders that have earlier onset and are typically passed down through generations. For example, early onset Alzheimer's disease is caused by mutations in certain genes and usually affects individuals between the ages of 30 and 60. On the other hand, chromosomal disorders, such as Down syndrome, are caused by an incorrect number of chromosomes and are more likely to occur as women age, due to an increase in chromosomal nondisjunction events during meiosis.