Heterozygous mutations in CS are mutant alpha-thalassemia genes detected using PCR-reverse dot hybridization. Mutant α-thalassemia is due to point mutations or deletions of a few bases in the α-gene. Forty-six point mutations have been found to exist, and three α2 gene point mutations have been reported to be common in the Chinese population: aWS, aQS, and aCS. CS mutations are used as a complementary test for the three deletion types of α-thalassemia. Patients suspected of having an underdiagnosis of α-thalassemia are diagnosed with CS/QS/WS mutations by PCR-reverse point hybridization to determine the specific type of mutation. Different abnormal genotypic mutations can produce anemia symptoms of varying severity. Heterozygous mutations in CS, i.e., the presence of a blue spot at the mutation detection probe with a similar intensity of coloration to the corresponding wild-type probe, make the locus heterozygous for the wild and the mutation. Specific diagnosis and testing should be done under the supervision of a physician.