Practice question

Deletion mapping exploits defined chromosomal deletions removing contiguous segments to locate genes physically relative to breakpoints. Heterozygous deletion crossed to recessive point mutant uncovers mutant phenotype if point mutation lies inside deletion interval because no wild allele remains; if outside wild allele from deletion chromosome restores function. Using overlapping deletions of known breakpoints gene order determined by pattern of uncovering across deletion panel. Technique predated sequencing and provided essential physical map complementing recombination maps and revealing gene proximity and clustering accurately.