Molecular detection of Spanish deltabeta-thalassemia associated with beta-thalassemia identified during prenatal diagnosis.

BACKGROUND

beta-Thalassemia is one of the most common single gene disorders and is widely distributed in the Mediterranean region. The deltabeta-thalassemias are a rare group of disorders, however in Spain the Spanish deltabeta0 thalassemia that removes 114 kb of beta-globin cluster is quite frequent.

METHODS

To establish a molecular diagnosis of beta-thalassemia in a second-trimester fetus from a couple who are beta-thalassemia carriers, a rapid real-time PCR method was performed to detect major mutations prevalent in people of the Mediterranean basin (IVS I-1, IVS I-6, IVS I-110, CD-6, CD-37, and CD-39). The Spanish deltabeta0 deletion was detected using PCR with deletion-specific primers.

RESULTS

The father was diagnosed as a carrier for the IVSI-6 (T>C) mutation and the mother as carrier for the Spanish deltabeta0 deletion. The fetus was a compound heterozygote for both those mutations. The phenotype of compound heterozygosity for deltabeta/beta-thalassemia can range from mild thalassemia intermedia to thalassemia major. After confirming these results in the DNA from amniocentesis obtained at the 20th week of gestation, the couple decided to terminate the pregnancy.

CONCLUSIONS

This paper reports the first molecular characterization of Spanishdeltabeta0-thalassemia associated with beta-thalassemia IVSI-6, and confirms the importance of prenatal genetic testing for single gene disorder such as beta-thalassemia.