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A 6-year-old girl with hemoglobin H disease
Takahiro Ueda1, Makoto Migita, Miho Yamanishi
1Department of Pediatrics, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan. yuri878t@nms.ac.jp
Insights
Hemoglobin H (HbH) disease, a severe form of alpha-thalassemia, is rare in Japan. This case highlights a Japanese-Filipino family with HbH disease, emphasizing the need for increased awareness and monitoring.
Area of Science:
- Genetics
- Hematology
- Molecular Biology
Background:
- Hemoglobin H (HbH) disease is a severe, nonfatal form of alpha-thalassemia syndrome.
- It typically results from molecular defects in three of the four alpha-globin genes, leading to reduced alpha-globin expression.
- HbH disease is considered rare in Japan.
Observation:
- A 6-year-old girl presented with profound hypochromic and microcytic anemia.
- Genetic analysis of her family revealed a Japanese father with a 3.7-kb deletion (-α(3.7)/αα) and a Filipino mother with a Filipino-type deletion of both alpha-globin genes (--(FIL)/αα).
- Neither parent exhibited anemia.
Findings:
- The patient was diagnosed with HbH disease, carrying a heterozygous genetic abnormality (--(FIL)/-α(3.7)).
- This specific genetic combination resulted in severe anemia despite unaffected parents.
Implications:
- The increasing number of marriages between Japanese individuals and people from thalassemia-endemic regions suggests a potential rise in HbH disease incidence in Japan.
- Long-term follow-up is crucial for managing complications and improving the quality of life for patients with HbH disease.
- This case underscores the importance of genetic counseling and screening in mixed-ancestry populations.
Abstract:
Hemoglobin H (HbH) disease is the severe nonfatal form of α-thalassemia syndrome. It is usually caused by molecular defects of 3 of 4 α-globin genes (--/-α) which cause α-globin expression to be decreased. HbH disease is rare in Japan. Here, we report on a 6-year-old girl with HbH disease who had profound hypochromatic and microcytic anemia. Analysis of the α-globin genes of the patient's family showed that the father, who was Japanese, had an abnormal gene with a 3.7-kb deletion (-α(3.7)/αα), and the mother, who was Filipino, had a deletion removing both α-globin genes of the Filipino type (--(FIL)/αα). Neither parent had anemia. The patient was found to have HbH disease with a heterozygous genetic abnormality (--(FIL)/-α(3.7)). Recently, the number of marriages of Japanese to natives of areas where thalassemia is epidemic has increased. Therefore, the incidence of HbH disease can be expected to increase in Japan. Long-term follow-up will be needed to evaluate the long-term complications and to improve the quality of life of patients with HbH disease.
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