Ligase Chain Reaction

                          In this method, a thermostable ligase is used to specifically bond two adjacent oligonucleotides, which hybridize to a complementary target with perfect base pairing at the junction. This approach enables single base pair differences to be detected at the ligation junction. The design of primers with distinct labels for different base substitutions allows for simultaneous detection of several changes. This technique has been applied to the screening of the 31 most frequent mutations in the cystic fibrosis gene in a multiplex oligonucleotide ligation assay.

                         Sickle cell disease refers to a collection of autosomal recessive genetic disorders characterized by a hemoglobin variant (Hb S) which differs from hemoglobin A in having a single amino acid substitution on the β-chain. Individuals who are affected with other types of sickle cell disease are compound heterozygotes, possessing one copy of the Hb S variant and one copy of a different β-globin gene variant such as Hb C or Hb β-thalassemia. CE has been applied to the detection of both hemoglobin forms Hb S and Hb C in prenatal diagnoses of sickle cell diseases.