Molecular Analysis ofα/β-Thalassemia in A Southern Chinese Population

Abstract

Thalassemia is endemic to many regions in southern China. The screening of severe determinants of thalassemia is of critical importance in management and control of thalassemia. We designed a protocol based on microarray technology to screen for a spectrum of alpha/beta-globin gene mutations in the Chinese population. A total of 38 probes were capable of screening 98% of alpha/beta-globin gene mutations in the China population, including 16 mutations of beta-globin [beta(41-42)(-TCTT), IVSII-654(C-->T), beta17(A-->T), -28(A-->G), beta(71-72)(+A), beta(71-72)(+T), HbE26(G-->A), -29(A-->G), beta(27-28)(+C), IVSI-1(G-->T), IVSI-5(G-->C), beta(14-15)(+G), IVSII-5(G-->C), beta41(+T), 37(G-->A), and beta43(G-->T)] and five mutations of alpha/beta[three deletions of -alpha;(3.7), -alpha(4.2), and --(SEA); two nondeletions of alpha(Quong Sze) codon alpha125(T-->C) and alpha(Constant Spring) codon alpha142(T-->C)]. Multiplex PCR products were amplified from human genomic DNA and allowed to hybridize with the oligonucleotide array. alpha/beta-Globin genotypes were assigned by quantitative analysis of the hybridization results. The protocol, standardized by analysis of 100 thalassemia samples with known mutations and 13 recombinant plasmids, was 100% reliable in genotyping all mutant alleles. In subsequent screening of 2,030 Chinese with unknown mutations, the protocol was 100% accurate. This method provides unambiguous detection of complex combinations of heterozygous, compound heterozygous, and homozygous alpha/beta-thalassemia genotypes. The protocol was also flexible, detecting globin gene mutations from different population groups.

Molecular spectrum of α-globin gene mutations in the Aegean region of Turkey: first observation of three α-globin gene mutations in the Turkish population

“…It is also reported to be the most prevalent mutation in many populations across various continents including Europe [14][15][16][17][18]. Another single α-gene deletion mutation is −α 4.2 mutation which is more prevalent in south Asia [17,19]. No one in the population studied carried −α 4.2 mutation.…”

“…In Guvenc et al's study, −(α) 20.5 mutation was the fourth most commonly seen mutation in 225 individuals carrying α-thalassemia allele or alleles [8]. It has also been reported rarely in the south Asia, Middle East and Arab countries [19][20][21][22][23][24].…”

Beta-thalassemia

“…22 Other methods based on real-time PCR or microarray technology because of their reproducibility, rapidity, and easy handling are potentially suitable for the routine clinical laboratory. 23,24 If targeted mutation analysis fails to detect the mutation, scanning or sequence analysis can be used. Sensitivity of both mutation scanning and sequence analysis is 99%.…”

“…23,24 As previously mentioned, delta globin gene analysis may be necessary to define double heterozygotes for delta-and beta-thalassemia that may be mistaken for alpha-thalassemia trait. The suspicion of interacting delta-thalassemia may arise when borderline HbA 2 levels are found or when family studies show segregating delta-thalassemia (characterized by normal MCV-MCH and low HbA 2 ) and beta-thalassemia.…”

One single-tube PCR assay to detect both CD17 (A>T) and IVS-II nt-654 (C>T) homozygous mutations of β-thalassemia

“…Commonly, the occurring mutations of the β-globin gene are detected by a number of PCR-based procedures, such as RDB analysis or primer-specific amplification with a set of probes (10,13). Other methods based on real-time PCR or microarray technology (11,12) are incompatible for the routine clinical laboratory because of their cost and complexity.…”