Loss of heterozygosity means: (AIIMS Nov 2013)
|A||Loss of single arm of chromosome|
|B||Loss of mutant allele in mutant gene|
|C||Loss of normal allele in mutant gene|
|D||Loss of normal allele in normal gene|
"A child with inherited mutant RB allele in somatic cells is perfectly normal. Because such a child is a heterozygous at the Rb locus, it implies that heterozygosity for the Rb gene does not affect cell behavior. Cancer develops when the cell becomes homozygous for the mutant allele or in other words when the cell loses heterozygosity for the normal Rb gene (a condition known as LOH loss of heterozygosity)"