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The α+-thal deletion of 3.557 kb (NG_000006.1: g.32745_36301del, -αMAL3.5), involving the entire α2-globin gene, was identified in a Chinese family by multiplex ligation-dependent probe amplification (MLPA) followed by gap-polymerase chain reaction (gap-PCR) and sequencing. The proband, a compound heterozygote for this mutant gene and the Southeast Asian (- -SEA; NG_000006.1: g.26264_45564del19301) deletion, had a phenotype of Hb H disease [hemoglobin (Hb) 7.6 g/dL, mean corpuscular volume (MCV) 60.0 fL, Hb H (β4) 0.7%, Hb Bart's (γ4) 2.4% and Hb A2 1.1%]; one of her sisters with same genotype showed a similar phenotype. Another two family members, who were carriers of this mutant gene, had a hematological phenotype of a silent α-thal. The 5' and 3' breakpoints of this deletion are located at the Y2 and Y1 boxes, respectively, therefore, it probably originated from an unequal crossover between these two homologous boxes. This mutation constitutes an additional heterogeneous defect causing α-thal in the Chinese population and would be valuable for elucidating the arrangement in the human α-globin gene cluster.

Background Xp11.22 duplications have been reported to contribute to nonsyndromic intellectual disability (ID). The HUWE1 gene has been identified in all male Xp11.22 duplication patients and is associated with nonsyndromic ID. Currently, few Xp11.22 duplication cases have been reported in the Chinese population, with limited knowledge regarding the role of other genes in this interval. Case presentation We investigated four unrelated Chinese male Xp11.22 duplication patients, performed a comprehensive clinical evaluation for the patients and discussed the role of other genes in this interval. All patients presented with similar clinical features, including ID, speech impairments and motor delay, which were mostly consistent with those of the Xp11.22 duplication described previously. We searched and compared all cases and noted that one of the probands (Family 1) and DECIPHER case 263,219, who carried small overlapping duplications at Xp11.22 that only covered the entire HSD17B10 gene, also suffered from ID, suggesting the important role of HSD17B10 in this interval. Furthermore, three patients (two probands in Families 3 and 4 and DECIPHER case 249,490) had strikingly similar hypogonadism phenotypes, including micropenis, small testes and cryptorchidism, which have not been previously described in Xp11.22 duplication patients. Interestingly, the FGD1 gene was duplicated only in these three patients. Sufficient evidence has suggested that haploinsufficiency of the FGD1 gene causes Aarskog-Scott syndrome, which is characterized by hypogonadism and other abnormalities. Given that, we are the first group to propose that FGD1 may be a potential dosage-sensitive gene responsible for the hypogonadism observed in our patients. Conclusion We reported novel genotypes and phenotypes in Chinese male Xp11.22 duplication patients, and the HSD17B10 and FGD1 genes may be involved.

In practice, gap-polymerase chain reaction (gap-PCR) and reversed dot-blot are the two most frequently used molecular diagnostic methods for α-thalassemia (α-thal) genotyping. Here, we describe three Chinese individuals from three unrelated families in whom a polymorphism on the α-globin gene cluster led to diagnostic pitfalls. During general molecular diagnosis of thalassemia, three individuals with unexplained results were found. Blood or chorionic villus samples were collected from these three individuals and their family members. Hematological investigations and genetic tests were performed. In Family 1, a polymorphism of HBA2: c.301-24delinsCTCGGCC at the annealing site of the forward primer used in the PCR-reverse dot-blot assay was identified, leading to allele drop-out during the PCR amplification process. In Family 2, a synonymous mutation of C>T substitution at codon 125 of the α2 gene (HBA2: c.376C>T) was identified, leading to the failure of PCR-reversed dot-blot for the HBA2: c.377T>C (Hb Quong Sze or Hb QS) mutation. In Family 3, the size of the PCR fragment from the α2-globin allele carrying the HBA2: c.-771_-428del mutation was smaller and nearly equal to the size of the fragment corresponding to the -α4.2 (leftward) deletion; we also found that the HBA2: c.-771_-428del mutation was linked to a known HBA1: c.-673A>G mutation in this family. In conclusion, diagnostic errors may be caused by technical pitfalls or inherent properties of the DNA sample. All logical steps should be taken to monitor and thus preclude such events.

Objectives The aim of the study was to set up an alternative automatic molecular diagnostic method for deletional α-thalassaemia mutations without gel electrophoresis. Methods Based on the sequence variation within the two Z boxes and melting curve analysis of dually labelled probes, a real-time PCR assay was developed and validated for the rapid detection of major α-genotypes (-- SEA /αα, -- SEA /-α 3.7 , -- SEA /-α 4.2 , -- SEA /-- SEA , -α 3.7 /-α 3.7 and -α 4.2 /-α 4.2 ). Results Samples with the -α 3.7 /-α 3.7 , -α 4.2 /-α 4.2 , -- SEA /αα, -- SEA /-α 3.7 , -- SEA /-α 4.2 , and -- SEA /-- SEA genotypes could be clearly distinguished. The accuracy of this technique for these samples was 100% sensitivity and specificity. Conclusion This technique is rapid and reliable, demonstrating feasibility for use in large-scale population screening and prenatal diagnosis of deletional Hb H disease and Hb Bart's hydrops fetalis.

We identified two novel δ-globin gene mutations in two families during routine thalassemia screening. One missense mutation at codon 73 on the δ-globin gene [δ73(E17)Asp→Val, HBD: c.221A>T] which results in a Hb A2 variant homologous to the β-globin gene variant called Hb Mobile [β73(E17)Asp→Val, HBB: c.221A>T] and we have named this variant Hb A2-Henan. The other is a nonsense mutation [δ7(A4)Glu→Stop, HBD: c.22G>T] which gives rise to a stop codon (TAG) at codon 7, resulting in δ0-thalassemia (δ0-thal). The Hb A2 in one individual with homozygous HBD: c.22G>T was absent.

Background The “gray zone” of borderline hemoglobin A 2 (Hb A 2 ) may be present in a large section of the population, especially in countries where thalassemia is common. However, very little is currently known of the molecular basis of borderline Hb A 2 in Chinese individuals. Method In this study, we performed a comprehensive analysis of the globin genotypes and KLF1 gene mutations associated with borderline Hb A 2 in 165 Chinese subjects. Result Fifteen (9.1%) were positive for a molecular defect in the α-,β-globin genes, of whom, α-thalassemia mutations and α-globin gene triplication were found in eleven cases, accounting for about 73.3% of these globin gene defects. Twenty (12.1%) were positive for a molecular defect in the KLF1 gene. Eight different mutations were identified, six of which are here reported for the first time. The most common is the G176AfsX179 mutation, accounting for 50% of the total. Conclusions The molecular characterization of borderline Hb A 2 in Chinese individuals is significantly different than in Italian population. Our data is conductive to provision of genetic counseling for Chinese individuals with borderline Hb A 2 .

The aim of the present study was to find the most prevalent structural hemoglobin (Hb) variants in southern China and to present hematological and molecular data of abnormal Hbs in the population from southern China. The type and frequency of structural Hb variants and their hematological and molecular characteristics were identified in 131 individuals from 30,848 unrelated partners who were referred to the prenatal clinic of Dongguan MaternalChildren Health Hospital, Dongguan, Guangdong, People's Republic of China (PRC) from 2011 to 2013. α-Globin or β-globin chain variants were screened using a capillary electrophoresis (CE) system, and α-globin or β-globin gene mutations were confirmed using sequencing techniques. The gene frequency of Hb variants was 0.4% (131/30,848). The most common α-globin variants were Hb Constant Spring (Hb CS, HBA2: c.427T C) (0.2%), followed by Hb Q-Thailand (HBA1: c.223G C) and Hb G-Honolulu (HBA2: c.91G C). The most common β-globin variant was Hb E (HBB: c.79G A) (0.09%), followed by Hb New York (HBB: c.341T A). Our results provide a detailed prevalence and molecular characterization of abnormal Hbs in the population of the Dongguan region. These findings have important implications for a region with a high frequency of α- and β-thalassemias.

We have identified four Chinese individuals from three unrelated families with raised Hb A2 levels. The anti-Lepore hybrid hemoglobin (Hb) variant was amplified using a pair of primers, 5' to the β-globin gene Cap site and 3' to the δ-globin gene polyadenylation site (polyA) region, respectively. Direct sequencing of the βδ fusion products confirmed the anti-Lepore Hong Kong (NG_000007.3: g.63154_70565dup) variant. We found that this anti-Lepore variant is positioned in zone 3 on the capillary electrophoresis system. It may help in differential diagnosis of Hb variants and providing better information in clinical counseling.