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Prevention of beta-thalassemia major by antenatal screening in Hong Kong
1Department of Paediatrics, Tuen Mun Hospital, New Territories, Hong Kong.
Insights
Despite antenatal screening for beta-thalassemia major, new cases persist in Hong Kong. Factors like late visits, missed screenings, and population migration hinder prevention efforts for this severe genetic blood disorder.
Area of Science:
- Medical Genetics
- Hematology
- Public Health
Background:
- Thalassemias are prevalent genetic blood disorders.
- Beta-thalassemia major is a severe form preventable through antenatal screening.
- Despite existing programs, new diagnoses continue to occur.
Purpose of the Study:
- To investigate the reasons behind the continued diagnosis of severe beta-thalassemia syndromes in Hong Kong.
- To identify factors undermining the effectiveness of antenatal screening programs.
Main Methods:
- Retrospective study of 34 children diagnosed with severe beta-thalassemia syndromes between 1990-1996.
- Analysis of parental screening status and reasons for missed diagnoses.
Main Results:
- 27 children had homozygous beta-thalassemia, 7 had beta E thalassemia.
- Key reasons for births included late/no antenatal visits (24.2%), lack of maternal (39.4%) or paternal (21.2%) screening, and parental refusal (9.1%).
- Population migration from mainland China presents a growing challenge.
Conclusions:
- Several factors compromise the effectiveness of current antenatal screening for thalassemias.
- Increased awareness among medical practitioners and the public is crucial.
- Population mobility necessitates revised prevention strategies for beta-thalassemia major.
Abstract:
The thalassemias are common in Hong Kong. One of the severe forms, beta-thalassemia major, has been preventable locally by antenatal screening since 1983. Yet new patients are still being diagnosed. In this retrospective study, 34 children with severe beta-thalassemia syndromes were diagnosed in two major public hospitals between 1990 and 1996. They included one pair of identical twins and two pairs of siblings. Twenty-seven (79%) had homozygous beta-thalassemia and seven (21%) had beta E thalassemia. All but four (12%) were transfusion dependent. Fifty-five (89%) parents had been evaluated for their thalassemia status. Forty-eight had beta-thalassemia traits and seven were hemoglobin E carriers. The reasons for the birth of these children with severe beta-thalassemia syndromes were (1) late or no antenatal visit (n = 8, 24.2%), including three cross-border deliveries in which the pregnant mothers came from mainland China to Hong Kong for confinement, (2) lack of maternal screening (n = 13, 39.4%), (3) lack of paternal screening (n = 7, 21.2%), (4) parental refusal (n = 3, 9.1%), and (5) unknown (n = 2, 6.1%). These findings suggest that several factors undermine the effectiveness of antenatal screening for prevention of thalassemias. Many medical practitioners and the general public are still not aware of the screening procedures. The migration of population from mainland China to Hong Kong may result in the birth of many more children with beta-thalassemia major.