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Case Reports
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α -thalassemia due to chimerism
NIHF and account for approximately 20% of cases.
Unusual survival of a twin with homozygous
However, in the Southeast Asia (SEA) region, which 0
Hydrops fetalis is a common birth defect in obstetrics. Non-immune hydrops fetalis (NIHF) accounts for almost 90% of cases of hydrops and its prevalence is estimated to be 1 in 1,700-3,000 pregnancies.1 Worldwide, cardio- vascular abnormalities are the most common cause of
includes southern China, homozygous α -thalassemia is the most common cause of NIHF (approximately 55%), since α-thalassemia has a high prevalence in this region.2 It has been reported that there are at least 26,000 at risk pregnancies and 6,600 affected fetuses per year.3 Consequently, homozygous α0-thalassemia is a key dis- ease for prenatal diagnosis in this region.
ABC
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Figure 1. The family pedigree, growth status of the twins in utero and the molecular analysis of α-globin gene in patient II1. (A) Pedigree of the Zhaoqing family. The patient II1 is labeled with an arrow. The hematological phenotype data of I1, I2 and II1 are list- ed. The II1 patient had a blood transfusion. (B) The biparietal diameter of the twins in utero, compared to the standard population.7,8 (C) Femur length (FL) of twins in utero, compared to the stan- dard population.7,8 The II2 patient’s FL did not increase after gestational week 31. (D) The gap-polymerase chain reaction and multiplex liga- tion-dependent probe amplifi- cation (MLPA) results for the family. The normal band (1,800 bp) and --SEA band (1,300 bp) were observed in I1 and I2. A faint normal band was also observed in II1, along with a bright --SEA band (left). Scattering of II1 (red cir- cles) shows the low level of the α-globin gene in the SEA
H deletion region, from probe 8 to probe 29 (chr16:217274- 231141, hg19), while α0-thal samples (blue rhombus) usu- ally drop to “0” in this region (right). (E) The quantitative analysis of the α-globin gene shows the existence of the gene in genomic DNA (gDNA) from blood, hair follicle and oral mucosa samples from II1. The expression of α-globin mRNA (F) and z-globin mRNA (G) were detected in blood cells from II1. (H) Haplotype analysis of one SNP in the SEA deletion region shows that the residual α-globin gene in II1 was inherited from his mother (I2). M: marker; N: normal control; C: carrier of -- SEA/αα control; α0-thal: Homozygous α0-thalassemia control; SEA: Southeast Asian; SNP: single nucleotide poly-
morphism.
haematologica | 2021; 106(5)
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