Characterisation of two unusual cases of haemoglobin Bart’s hydrops foetalis caused by –SEA and large novel α-globin gene cluster deletions

• Published in: Journal of international medical research Vol. 49; no. 2; p. 300060521993642
• Main Authors: Wang, Yunan, Xiong, Ying, Liu, Chang, Lu, Jian, Wang, Jicheng, Qin, DanQing, Liu, Ling, Wu, Jing, Zhao, Xin, Fang, Liyuan, Du, Li, Yin, Aihua
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.02.2021; Sage Publications Ltd
• Subjects: alpha-Globins - genetics; alpha-Thalassemia - diagnosis; alpha-Thalassemia - genetics; Blood diseases; Case Report; China; Edema; Female; Gene Deletion; Hemoglobin; Hemoglobins, Abnormal; Humans; Hydrops Fetalis - diagnosis; Hydrops Fetalis - genetics; Multigene Family; Mutation; Pregnancy; Prenatal Diagnosis; China; α-thalassaemia; Haemoglobin Bart’s hydrops; SEA deletion; SNP array; novel deletions; multiplex ligation-dependent probe amplification
• DOI: 10.1177/0300060521993642
• ISSN: 0300-0605; 1473-2300

Background We describe 2 unusual haemoglobin (Hb) Bart’s hydrops cases that could not be explained by traditional factors. Case presentation: Two families with a diagnosis or history of foetal hydrops were enrolled. A suspension-array system was used to detect the 23 most frequent mutations in southern China. Multiplex ligation-dependent probe amplification (MLPA) was used to screen for possible deletions. Precise characterisation of the breakpoints of the novel variants and uniparental disomy analysis were performed using a single nucleotide polymorphism (SNP) array. Quantitative fluorescence PCR was used to eliminate maternal cell contamination and nonpaternity. In case 1, the suspension-array system indicated a maternal heterozygous (–SEA/) deletion, and the paternal sample was negative. The foetal hydrops was caused by the maternal (–SEA/) deletion and a de novo α-globin gene deletion (–193). In case 2, the paternal sample had a heterozygous (–SEA/) deletion, and MLPA and SNP array analysis revealed a large maternal deletion (–227) that encompassed the α-globin gene, which explained the history of Hb Bart’s foetal hydrops. Conclusions Our cases describe 2 new α0-thalassaemia deletions and illustrate the importance of using a combination of methods to detect rare types of α-thalassaemia.