Definition of Linkage Disequilibrium
Linkage disequilibrium is a phenomenon in which the alleles and the molecular markers form an association with each other but their frequency is prominently higher than expected by a random chance. According to population genetics, this is known as a non-random association of alleles that are present at different loci in a population. They are said to be in disequilibrium when their frequency changes.
This disequilibrium is affected by a number of factors such as rate of mutation, genetic drift, genetic recombination, genetic linkage, etc. this concept is also applied to the asexual organisms and it is also known as gamete phase disequilibrium (though independent from the presence of gametes).