Which chromosomal mutation involves loss of genetic material from a chromosome?

• A. Duplication chromosomal mutation
• B. Deletion chromosomal mutation
• C. Inversion chromosomal mutation
• D. Translocation chromosomal mutation

Answer: (B)

Loss of genetic material from a chromosome happens through a deletion, a chromosomal mutation in which a segment of the chromosome is removed. When that piece is lost, the genes it contained are also lost, which can disrupt development or create disease depending on what genes were present. Deletions can be terminal, where the end of the chromosome is missing, or intercalary, where an internal segment is deleted. This differs from other chromosomal mutations: duplication adds material and increases gene copies; inversion rearranges a segment within the chromosome without losing material; translocation moves a segment to another chromosome, which can alter regulation or create new gene fusions. An example is Cri du chat syndrome, caused by deletion of part of chromosome 5.