High resolution melting analysis: a rapid screening and typing tool for common ß-thalassemia mutation in Chinese population.

ß-thalassemia is a common inherited disorder worldwide including southern China, and at least 45 distinct ß-thalassemia mutations have been identified in China. High-resolution melting (HRM) assay was recently introduced as a rapid, inexpensive and effective method for genotyping. However, there was no systemic study on the diagnostic capability of HRM to identify ß-thalassemia. Here, we used an improved HRM method to screen and type 12 common ß-thalassemia mutations in Chinese, and the rapidity and reliability of this method was investigated. The whole PCR and HRM procedure could be completed in 40 min. The heterozygous mutations and 4 kinds of homozygous mutations could be readily differentiated from the melting curve except c.-78A>G heterozygote and c.-79A>G heterozygote. The diagnostic reliability of this HRM assay was evaluated on 756 pre-typed genomic DNA samples and 50 cases of blood spots on filter paper, which were collected from seven high prevalent provinces in southern China. If c.-78A>G heterozygote and c.-79A>G heterozygote were classified into the same group (c.-78&79 A>G heterozygote), the HRM method was in complete concordance with the reference method (reverse dot blot/DNA-sequencing). In a conclusion, the HRM method appears to be an accurate and sensitive method for the rapid screening and identification of ß-thalassemia mutations. In the future, we suggest this technology to be used in neonatal blood spot screening program. It could enlarge the coverage of ß-thalassemia screening program in China. At the same time, its value should be confirmed in prospectively clinical and epidemiological studies.

Hemoglobinopathy: molecular epidemiological characteristics and health effects on Hakka people in the Meizhou region, southern China.

BACKGROUND: Hemoglobinopathies are the most common inherited diseases in southern China. However, there have been only a few epidemiological studies of hemoglobinopathies in Guangdong province. MATERIALS AND METHODS: Peripheral blood samples were collected from 15299 "healthy" unrelated subjects of dominantly ethnic Hakka in the Meizhou region, on which hemoglobin electrophoresis and routine blood tests were performed. Suspected cases with hemoglobin variants and hereditary persistence of fetal hemoglobin (HPFH) were further characterized by PCR, DNA sequencing, reverse dot blot (RDB) or multiplex ligation-dependent probe amplification (MLPA). In addition, 1743 samples were randomly selected from the 15299 subjects for thalassemia screening, and suspected thalassemia carriers were identified by PCR and RDB. RESULTS: The gene frequency of hemoglobin variants was 0.477% (73/15299). The five main subgroups of the ten hemoglobin variants were Hb E, Hb G-Chinese, Hb Q-Tahiland, Hb New York and Hb J-Bangkok. 277 cases (15.89%, 277/1743) of suspected thalassemia carriers with microcytosis (MCV<82 fl) were found by thalassemia screening, and were tested by a RDB gene chip to reveal a total of 196 mutant chromosomes: including 124 α-thalassemia mutant chromosomes and 72 ß-thalassemia mutant chromosomes. These results give a heterozygote frequency of 11.24% for common α and ß thalassemia in the Hakka population in the Meizhou region. 3 cases of HPFH/δß-thalassemia were found, including 2 cases of Vietnamese HPFH (FPFH-7) and a rare Belgian( G)γ((A)γδß)°-thalassemia identified in Chinese. CONCLUSIONS: Our results provide a detailed prevalence and molecular characterization of hemoglobinopathies in Hakka people of the Meizhou region. The estimated numbers of pregnancies each year in the Meizhou region, in which the fetus would be at risk for ß thalassemia major or intermedia, Bart's hydrops fetalis, and Hb H disease, are 25 (95% CI, 15 to 38), 40 (95% CI, 26 to 57), and 15 (95% CI, 8 to 23), respectively.

Development and evaluation of a reverse dot blot assay for the simultaneous detection of common alpha and beta thalassemia in Chinese.

Thalassemia is the commonest inherited autosomal recessive disorders of hemoglobin in southern China. We developed and evaluated a reverse dot blot (RDB) assay combined with flow-through hybridization technology platform for the rapid and simultaneous identification of 5 types of α-thalassemia and 16 types of ß-thalassemia common in Chinese. Reliable genotyping of wild-type and thalassemic genomic DNA samples was achieved by means of a gene chip on which allele-specific oligonucleotide probes were immobilized on a nylon membrane. This method involved two multiplex PCR amplification systems of α-thalassemia and ß-thalassemia and one time of hybridization. The whole procedure starting from blood sampling to the identification of thalassemia genotype required less than 4h. The diagnostic reliability of this reverse dot blot assay was evaluated on 427 samples (387 cases of thalassemia and 40 healthy persons) by using direct DNA sequence analysis and gap-PCR in a blind study. These samples included 377 cases of blood, 7 cases of amniotic fluid, 18 cases of chorionic villus, and 25 cases of cord blood. The RDB gene chip was in complete concordance with the reference method. The reverse dot blot assay was a simple, rapid, accurate, and cost-effective method to identify common thalassemia genotypes in the Chinese population.