Preimplantation genetic diagnosis for beta-thalassemia using single-cell DNA analysis for codons 17 and 26 of beta-globin gene

Attitudes Toward Pre-implantation Genetic Diagnosis (PGD) for Genetic Disorders Among Potential Users in Malaysia

While pre-implantation genetic diagnosis (PGD) is available and legal in Malaysia, there is an ongoing controversy debate about its use. There are few studies available on individuals' attitudes toward PGD, particularly among those who have a genetic disease, or whose children have a genetic disease. To the best of our knowledge, this is, in fact, the first study of its kind in Malaysia. We conducted in-depth interviews, using semi-structured questionnaires, with seven selected potential PGD users regarding their knowledge, attitudes and decisions relating to the use PGD. The criteria for selecting potential PGD users were that they or their children had a genetic disease, and they desired to have another child who would be free of genetic disease. All participants had heard of PGD and five of them were considering its use. The participants' attitudes toward PGD were based on several different considerations that were influenced by various factors. These included: the benefit-risk balance of PGD, personal experiences of having a genetic disease, religious beliefs, personal values and cost. The study's findings suggest that the selected Malaysian participants, as potential PGD users, were supportive but cautious regarding the use of PGD for medical purposes, particularly in relation to others whose experiences were similar. More broadly, the paper highlights the link between the participants' personal experiences and their beliefs regarding the appropriateness, for others, of individual decision-making on PGD, which has not been revealed by previous studies.

Molecular analysis of beta-globin gene mutations among Thai beta-thalassemia children: results from a single center study

Background

Beta-thalassemia is one of the most common genetic disorders in Thailand. Clinical phenotype ranges from silent carrier to clinically manifested conditions including severe beta-thalassemia major and mild beta-thalassemia intermedia.

Objective

This study aimed to characterize the spectrum of beta-globin gene mutations in pediatric patients who were followed-up in Phramongkutklao Hospital.

Patients and methods

Eighty unrelated beta-thalassemia patients were enrolled in this study including 57 with beta-thalassemia/hemoglobin E, eight with homozygous beta-thalassemia, and 15 with heterozygous beta-thalassemia. Mutation analysis was performed by multiplex amplification refractory mutation system (M-ARMS), direct DNA sequencing of beta-globin gene, and gap polymerase chain reaction for 3.4 kb deletion detection, respectively.

Results

A total of 13 different beta-thalassemia mutations were identified among 88 alleles. The most common mutation was codon 41/42 (-TCTT) (37.5%), followed by codon 17 (A>T) (26.1%), IVS-I-5 (G>C) (8%), IVS-II-654 (C>T) (6.8%), IVS-I-1 (G>T) (4.5%), and codon 71/72 (+A) (2.3%), and all these six common mutations (85.2%) were detected by M-ARMS. Six uncommon mutations (10.2%) were identified by DNA sequencing including 4.5% for codon 35 (C>A) and 1.1% initiation codon mutation (ATG>AGG), codon 15 (G>A), codon 19 (A>G), codon 27/28 (+C), and codon 123/124/125 (-ACCCCACC), respectively. The 3.4 kb deletion was detected at 4.5%. The most common genotype of beta-thalassemia major patients was codon 41/42 (-TCTT)/codon 26 (G>A) or beta^E accounting for 40%.

Conclusion

All of the beta-thalassemia alleles have been characterized by a combination of techniques including M-ARMS, DNA sequencing, and gap polymerase chain reaction for 3.4 kb deletion detection. Thirteen mutations account for 100% of the beta-thalassemia genes among the pediatric patients in our study.