The prevalence and spectrum of α and β thalassaemia in Guangdong Province: implications for the future health burden and population screening

Abstract

Aim: Thalassaemia is a good candidate disease for control by preventive genetic programmes in developing countries. Accurate population frequency data are needed for planning the control of thalassaemia in the high risk Guangdong Province of southern China. Methods: In total, 13 397 consecutive samples from five geographical areas of Guangdong Province were analysed for both haematological and molecular parameters.Results: There was a high prevalence of carriers of a thalassaemia (8.53%), b thalassaemia (2.54%), and both a and b thalassaemia (0.26%). Overall, 11.07% of the population in this area were heterozygous carriers of a and b thalassaemia. The mutation spectrum of a and b thalassaemia and its constitution were fully described in this area. This study reports the true prevalence of silent a thalassaemia in the southern China population for the first time. In addition, two novel mutations that give rise to a thalassaemia, one deletion resulting in b thalassaemia, and a rare deletion (22 THAI allele) previously unreported in mainland China were detected. The frequency of the most common mutation, the Southeast Asian type of deletion (22 SEA , accounting for 48.54% of all a thalassaemias) was similar to the total of two a + thalassaemia deletions (2a 3.7 and 2a 4.2 , accounting for 47.49% of a thalassaemia). Conclusion: Both a and b thalassaemia are widely distributed in Guangdong Province of China. The knowledge gained in this study will enable the projected number of pregnancies at risk to be estimated and a screening strategy for control of thalassaemia to be designed in this area.

A Melting Curve Analysis–Based PCR Assay for One-Step Genotyping of β-Thalassemia Mutations

“…Genomic DNA (gDNA) samples were collected from November 2008 to April 2010, and met the following eligibility criteria: (1) all had a record of hematologic phenotypes determined via full blood cell counts and a hemoglobin test, as previously described, 6 (2) all had HBB genotype information determined via RDB analysis or sequencing, 14 and (3) the template concentration was Ͼ10 ng/ L, with a 260-to 280-nm absorption ratio in the range of 1.6 to 2.0.…”

“…3,4 In China, the estimated incidence of carriers of ␤-thalassemia is as high as 7% in the Guangxi Province, and 1% to 6% in populations elsewhere in the endemic areas of southern China. [5][6][7][8] ␤-Thalassemia is a severe disease, and its treatment requires many resources, both medical and financial. While many cities in China have facilities for diagnosis and treatment of this disease, free medical services are not provided by the government in most rural areas.…”

“…To date, 45 single-nucleotide mutations and small deletions in HBB have been detected in the Chinese population. [5][6][7][8][9][10] Translation of the data into clinical practice requires a simple, reliable, cost-effective method that is able to detect all of these mutations. Among dozens of methods that have been developed for detecting ␤-thalassemia mutations, [11][12][13] reverse dot blot (RDB) analysis is the only method approved in China.…”

Two cases of homozygous α0‐thalassemia diagnosed prenatally in pregnancies at risk for β‐thalassemia in China

“…Thalassemia is one of the most common monogenic diseases in southern China 1 . Carriers of thalassemia are usually asymptomatic.…”

“…The carrier rates of α 0 -thalassemia (--SEA ) and β-thalassemia are 4.1% and 2.5%, respectively, in southern China 1 . This means that the chance of finding an individual with co-inheritance of α 0 -and β-thalassemia in the population is theoretically 1/1000.…”