Final answer:
Locus heterogeneity refers to a genetic disorder that is caused by mutations at multiple genetic loci. It describes different mutations across various genes resulting in a similar disease phenotype, unlike disorders caused by a single gene mutation.
Step-by-step explanation:
Locus heterogeneity refers to a genetic disorder that is caused by mutations at multiple genetic loci. This concept describes how different mutations can cause a similar or identical phenotype or disease. For example, if one genetic disorder can be caused by a mutation in any one of several different genes, it is said that this disorder exhibits locus heterogeneity. This is in contrast to a genetic disorder caused by mutations at a single genetic locus, which would not exhibit locus heterogeneity.
Many genetic disorders such as cancer, cystic fibrosis, and neurofibromatosis type I, arise from mutations in individual genes. However, when looking at the broader spectrum of genetic diseases, it becomes apparent that some conditions can be caused by alterations in multiple different genes spread across different chromosomes.
Therefore, the correct answer to the student's question is: A) Is caused by mutations at multiple genetic loci.