Practice question

Non-reciprocal homologous recombination leads to gene conversion, phenomenon where heteroduplex formed between polymorphic parental duplexes contains mismatched base pairs subject to mismatch repair that can correct either direction. If repair copies information from one allele converting other to same sequence, one allele replaces another without reciprocal product, producing 3:1 segregation instead of 2:2. Mechanism involves double-strand break repair with synthesis-dependent strand annealing. Gene conversion underlies concerted evolution of ribosomal DNA arrays, antigenic variation, and loss of heterozygosity driving tumor suppressor inactivation in somatic cells.