[Direct genotyping of an hereditary persistence of fetal hemoglobin deletion and rapid prenatal diagnosis of the fetus at-risk for compound heterozygote of this defect with beta-thalassemia in a Chinese family].

OBJECTIVE: To investigate the relationship between genotype and phenotype of a deletional hereditary persistence of fetal hemoglobin(HPFH) found in a Chinese family and explore an approach to rapid prenatal diagnosis for compound heterozygote of HPFH defects with beta-thalassemia. METHODS: By using the PCR-based method with three primers bridging a HPFH breakpoint and reverse dot blot (RDB) for detecting beta-thalassemia mutations, a Chinese family who had a propositus of six years old with intermediate thalassemia and requested prenatal diagnosis for the second pregnancy were screened. RESULTS: The propositus carried the HPFH deletion determinant inherited from her mother, and a codons 14-15 (+G) frameshift mutation causing beta-thalassemia from her father. Of six members in this family screened for this type of HPFH deletion, four were positive. Prenatal diagnosis of the fetus showed the same results as that of the propositus. An advice of termination of pregnancy was given and the result of prenatal diagnosis was confirmed in the DNA samples obtained after abortion. CONCLUSIONS: This is the first time to have performed prenatal diagnosis of Chinese family at-risk for compound heterozygotes for beta-thalassemia and HPFH in mainland China. The PCR assay for directly detecting the HPFH deletion is rapid and inexpensive and can be used as a routine in HPFH carrier screening and prenatal diagnosis.