Early Onset of Fetal Hydrops Associated with the α-Thalassemia – –THAIDeletion

Hb Bart's Hydrops Fetalis Syndrome and Hb H Disease Caused by Deletional Chiang Rai (- -CR) α0-Thalassemia in Two Unrelated Thai Families

α⁰-Thalassemia (α⁰-thal) Chiang Rai (- -^CR; NC_000016.10: g.144215_188843del) was identified as a novel 44.6 kb deletional type of α-thalassemia (α-thal), removing all α-like globin genes. However, little is known about the deleterious effects of this genetic disorder, particularly when it is combined with other types of thalassemia. We performed molecular analysis of the - -^CR deletion using gap-polymerase chain reaction (gap-PCR) in two independent families residing in Phayao and Chiang Mai, Thailand, with an unknown causative mutation for Hb Bart's hydrops fetalis syndrome and Hb H disease. Five out of seven individuals were diagnosed to be heterozygous for the - -^CR deletion. Of these, two also carried Hb H disease with compound heterozygosities for - -^CR and -α^3.7 (rightward) deletions. However, hematological parameters of the - -^CR carriers displayed microcytic hypochromic anemia that is comparable to other α⁰-thal traits. Although the prevalence of - -^CR has never been elucidated in a specific population, our study demonstrated that genotyping for - -^CR might be considered as an additional investigation for unexplained Hb Bart's hydrops fetal syndrome and Hb H disease.

Molecular Spectrum of α- and β-Thalassemia Mutations in a Large Ethnic Hakka Population in Southern China

Thalassemia is one of the most prevalent inherited disorders in southern China. However, there have been few reports on molecular characterization of α- and β-thalassemia (α- and β-thal) in the large Hakka population living in Meizhou, a city with high incidence of thalassemia in China. A total of 11,631 in- and outpatients in the Hakka area were analyzed by DNA-based α- and β-thal testing. Of all the samples, 4280 mutant chromosomes were detected, accounting in a total of 35.98%, of which 2864 (24.82%) α-thal mutants were detected, 1268 (10.09%) β-thal mutants were detected, 148 (1.27%) α- and β-thal mutants were detected. The following mutations - -^SEA/αα (Southeast Asian deletion), β^A/β^A; αα/αα, IVS-II-654 (C>T) (HBB: c.316-197C>T)/β^A; αα/αα, codons 41/42 (-TCTT) (HBB: c.126_129delCTTT)/β^A; and -α^3.7/αα, β^A/β^A were the most common thalassemia genotypes. The most common thalassemia genotype in the Hakka population in Meizhou was α-thal. In order to reduce the incidence of severe thalassemia in children, a prevention and control strategy should be established based on the distribution data of thalassemia genotyping. Our findings provide a valuable reference for clinical institutions or local governments to reduce the prevalence of thalassemia in the subtropical regions in the world.