[Genotype and Phenotype of α-Thalassemia Fusion Gene in Huadu District of Guangzhou, Guangdong Province of China].

OBJECTIVE: To explore the carrier rate, genotype and phenotype of α-thalassemia fusion gene in Huadu district of Guangzhou, Guangdong province of China, and provide data reference for the prevention and control of thalassemia. METHODS: A total of 10 769 samples who were screened for thalassemia in Maternal and Child Health Hospital of Huadu District from July 2019 to November 2020 were analyzed retrospectively. Blood cell analysis and hemoglobin (Hb) electrophoresis were performed. Thalassemia genes were analyzed by gap-PCR and PCR-reverse dot blot hybridization (PCR-RDB). RESULTS: A total of 9 cases with α-thalassemia fusion gene were detected in 10 769 samples (0.08%). There were 7 cases with fusion gene heterozygote, 1 case with compound of α-thalassemia fusion gene and Hb G-Honolulu, 1 case with compound of α-thalassemia fusion gene and Hb QS. The MCV results of 4 samples of blood cell analysis were within the reference range, the Hb A2 value of 1 case was decreased, and there were no other abnormalities found. CONCLUSION: The α-thalassemia fusion gene is common in Huadu district of Guangzhou, and heterozygotes are more common, and current screening methods easily lead to misdiagnosis.

Hb Huadu [α124(H7)Ser→Thr (TCC>ACC), HBA2: c.373T>A]: A Novel Variant of the α-Globin Gene.

Here, we report a novel α chain hemoglobin (Hb) variant found during routine thalassemia screening. This Hb variant can be detected by capillary electrophoresis (CE) but cannot be recognized by high performance liquid chromatography (HPLC). Sanger sequencing revealed a heterozygous missense substitution at nucleotide 373 on the HBA2 gene, which results in the replacement of serine by threonine at codon 124 [α124(H7)Ser→Thr (TCC>ACC), HBA2: c.373T>A]. It is the first report of this variant, named Hb Huadu for the birthplace of the proband. In addition, the proband coinherited the heterozygous codons 41/42 (-TTCT) (HBB: c126_129delCTTT) on the ß-globin gene.

[Molecular Epidemiological Characteristics and Differential Diagnosis of Common 뫧-Thalassemia/HPFH].

OBJECTIVE: To investigate the molecular epidemiological characteristics of common δß-thalassemia/hereditary persistence of fetal hemoglobin(HPFH) in the prepregnant population in Huadu, and to provide a laboratory basis for prevention and control of thalassemia. METHODS: Blood samples of childbearing age people in Huadu District of Guangzhou who participated in free thalassemia testing from January 2016 to July 2021 were collected for hematological parameters analysis and hemoglobin electrophoresis. Chinese Gγ+(Aγδß)0-thalassemia, SEA-HPFH and Taiwanese deletion ß-thalassemia were detected by Gap-PCR in the samples with higher HbF(≥5%). Primers were designed for the proximal HBG1 and HBG2 promoter, and the point mutations in the proximal promoter region were detected by Sanger sequencing. Hematology parameters data were statistically analyzed. RESULTS: Among 27 088 samples, Thirteen cases of Chinese Gγ+(Aγδß)0-thalassemia and thirty-three cases of SEA-HPFH were detected, which including 3 cases of Chinese Gγ+(Aγδß)0/ßN compounded with --SEA/αα and three cases of SEA-HPFH/ßN compounded with --SEA/αα. 6 carriers with Aγ-196 C>T were also detected; No Taiwanese thalassemia genetype was detected. The total detection rate of common δß-thalassemia/HPFH was 0.19% (52/27 088). There were significant differences in the levels of MCV, MCH, HbA2, and HbF among Chinese Gγ+(Aγδß)0-thalassemia, SEA-HPFH, Aγ-196 C>T (P<0.001). The hematological parameters of Aγ-196C>T combined with α0-thalassemia were similar to those of Chinese Gγ+(Aγδß)0-thalassemia carriers, and only HbA2 was significantly lower than that of the latter, which was helpful for clinical identification. CONCLUSION: δß-thalassemia/HPFH should be included in the scope of thalassemia prevention program in the prepregnant population in Huadu District, and hematological parameters can provide some basis for identifying different types of δß-thalassemia/HPFH.

Detection of rare thalassemia mutations using long-read single-molecule real-time sequencing.

Gap- polymerase chain reaction (PCR), reverse dot-blot assay (RDB), real-time PCR based multicolor melting curve analysis (MMCA assay), multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing are conventional methods to diagnose thalassemia but all of them have limitations. In this study, we applied single-molecule real-time (SMRT) sequencing following multiplex long-range PCR to uncover rare mutations in nine patients and their family members. The patients with different results between Gap-PCR and MMCA assay or with phenotype not matching genotype were included. Using SMRT sequencing, we first identified the carriers with αααanti3.7/HKαα, -α762bpα/αα (chr16:172,648-173,409), ααfusion/αQSα (in a trans configuration), two cases with novel gene rearrangements and another case with a novel 341 bp insertion in α-globin gene cluster, respectively. One carrier with --SEA/αααanti4.2, and two carriers with the coexistence of globin variant and an α-globin gene duplication were also found. Most importantly, we could determine two defects in α-globin gene cluster being a cis or trans configuration in a single test. Our results showed that SMRT has great advantages in detection of α-globin gene triplications, rare deletions and determination of a cis or trans configuration. SMRT is a comprehensive and one-step method for thalassemia screening and diagnosis, especially for detection of rare thalassemia mutations.

Detection of an α-Globin Fusion Gene Using Real-Time Polymerase Chain Reaction-Based Multicolor Melting Curve.

Genetic recombination between homologous sequences on the human globin gene clusters can lead to the creation of fusion genes. In this study, we report the detection of an α-globin fusion gene by using real-time polymerase chain reaction (qPCR)-based multicolor melting curve analysis (MMCA). The carriers of this fusion gene had a mild α-thalassemia phenotype with a normal hemoglobin (Hb) value and borderline hematological indices. Sequence analysis revealed that the mutant gene was the result of a fusion between the α2 and ψα1 genes. Our results indicate that the MMCA has the ability to detect the fusion gene, which is helpful for genetic counseling in thalassemia prevalent areas.

Hb Westmead (HBA2: c.369C>G): Hematological Characteristics in Heterozygotes with and without α0-Thalassemia.

Hb Westmead (α122(H5)His>Gln) (HBA2: c.369C>G) is a common α-globin variant causing α-thalassemia (α-thal) in Mainland China. In this study, we report the hematological characteristics in Hb Westmead carriers in a Chinese population. There were 546 individuals carrying Hb Westmead based on their molecular diagnosis: 514 Hb Westmead heterozygotes and 32 compound heterozygotes for Hb Westmead and α0-thal. Compared to common deletional α+-thal, Hb Westmead was associated with higher mean corpuscular hemoglobin (Hb) (MCH) values. Compound heterozygotes for Hb Westmead and α0-thal showed significantly higher Hb, mean corpuscular volume (MCV) and MCH values than subjects with deletional Hb H disease. When compared to α0-thal carriers, compound heterozygotes for Hb Westmead and α0-thal showed similar Hb values, but significantly lower MCV and MCH values. Our results indicate that Hb Westmead is a silent nondeletional α+-thal, with a deficiency of α-globin chain milder than deletional α+-thal, and compound heterozygotes for Hb Westmead/α0-thal have a phenotype similar to simple α0-thal.

[Construction of RevS gene knock-out mutant of Streptococcus suis serotype 2].

OBJECTIVE: To construct a gene knock-out mutant of response regulator named RevS in Streptococcus suis serotype 2 virulent strain 05ZYH33, and to investigate the effects of its deletion on the biological characters of this pathogen and the pathogenesis to mice and piglets. METHODS: Recombinant gene knock-out vector consisting of Spc(r) cassette was constructed and flanking was constructed consisting of Spc(r) cassette with flanking homology regions to the RevS genes while the isogenic RevS-deficient mutant was screened by allelic replacement. The effects of RevS deletion on the basic biological characters of 05ZYH33 including growth stability, colonial morphology, haemolysis, Gram staining, growth curve and protein expression were examined in vitro. The mice and piglets were infected with 10(8) CFU wild virulent and mutant isolates. RESULTS: PCR analysis confirmed that the coding genes of RevS were replaced completely by Spc(r) cassette and the basic biological characters of 05ZYH33 did not undergo any apparent change. Balb/c mice infection assay indicated that RevS play a role in the pathogenesis of Streptococcus suis infections, while no remarkable difference was observed in the piglets' pathogenesis infection rates between mutant isolates deltaA05ZYH33 and wild-type isolates 05ZYH33. CONCLUSION: The mutant of Streptococcus suis 05ZYH33 response regulator was successfully constructed, while the mutation did not obviously affect the bacterial biological characters, while the knock-out mutant of RevS was shown to be attenuated in pathogenesis to mice and piglets.

[Study on molecular epidemiology of major pathogenic Streptococcus suis serotypes in middle part of Jiangsu province].

OBJECTIVE: To determine the prevalence of Streptococcus suis and major pathogenic serotypes in middle part of Jiangsu province. METHODS: Tonsillar specimens from 303 slaughtered pigs aged 6 to 8 months were investigated for the presence of Streptococcus suis and major pathogenic serotypes by polymerase chain reaction (PCR) method. Bacteriological examination compared with molecular genetics identification for three Streptococcus suis isolates were also done. RESULTS: The overall carrier rate of Streptococcus suis was up to 88.0%, with the percentages of serotype 1(14), 2(1/2), 7 and 9 were 9.6%, 8.5%, 11.3% and 29.5% respectively in 2005. While in 2006, the prevalence of Streptococcus suis was 82.5%, with capsular types 1 (14), 2 (1/2), 7 and 9 were accounted for 17.6%, 2.4%, 25.8% and 20.0% of all the specimens. All the three isolates belonged to Streptococcus suis serotype 2,named 2a, 2f and 14e, which exhibiting the virulent phenotype cps2+/gdh+/mrp-/lepf-/sly-/fbps+/orf2+/89k-, cps2+/lgdh+/mrp-/epf-/sly-/fbps-/orf2-/89k- and cps2+/gdh+/mrp-/epf-/sly-/fbps/orf2-/ respectively. These isolates were all susceptible to amoxicillin, ampicillin, penicillin and resistant to amikacin and tetraycline. Clinical signs were not noted in BALB/c mice and rabbit. CONCLUSION: Prevalence of the Streptococcus suis among the healthy herds in the areas was very high, with various capsule types of Streptococcus suis involved in the same herds, and the virulent phenotype of these 3 isolates were very different from those prevalent Streptococcus suis serotype 2 virulent isolates frequently discovered from the epidemic areas.

Existence and characterization of allelic variants of Sao, a newly identified surface protein from Streptococcus suis.

Surface antigen one (Sao) is a newly identified protein from the major zoonotic pathogen, Streptococcus suis. In search of functional proteins related to the pathogenesis of Chinese S. suis 2 (SS2), unexpectedly, a variant of Sao protein was obtained. To test its prevalence in S. suis, PCR assay was adopted to address the coding genes systematically. It was found that there are three allelic variants of sao gene, namely sao-S, sao-M, and sao-L based on the different lengths of the genes (approximately 1.5, approximately 1.7, and approximately 2.0 kb, respectively). These differences were determined to be caused by heterogeneity within the number of C-terminal repeat sequences (R), which had been seen as a pathogenicity-related domain in the plant pathogen, Xanthomonas oryzae. Two variants (sao-M and sao-L) were only found in SS2. All three variant proteins were prepared in vitro and their biochemical and biophysical properties were characterized. A soluble form of Sao-M protein was then used as a capture antigen to develop an enzyme-linked immunosorbent assay method to detect antibodies against SS2 in convalescent pig sera. Taken together, the results exhibit the properties of Sao proteins and provide an efficient Sao-M-based method for monitoring SS2 infection.

[Clinical results of advanced gastric cancer patients treated with oxaliplatin-containing regimen].

BACKGROUND & OBJECTIVE: In vitro clinical research showed oxaliplatin (L-OHP) could obviously suppress the growth of gastric cancer cells in combination with most anti-cancer drugs and help these drugs to kill the tumor cells. This study was designed to evaluate the response and tolerance of oxaliplatin,leucovorin (LV), 5-fluorouracil (5-FU),and etoposide (VP-16) as first-line regimen in advanced gastric cancer, and compare with traditional chemotherapy regimen. METHODS: Forty-eight patients with advanced gastric cancer were divided into treatment group (L-OHP+LV+5-FU+VP-16) and control group(DDP+LV+5-FU+VP-16) using non-randomized method. L-OHP:135 mg/m(2), iv infusion 2 hours, d1(or DDP 20 mg, iv infusion, d1-5); LV:200 mg,iv infusion,d1-5; 5-FU:500 mg/m(2) CI 6 hours on d1-5; VP-16: 100 mg, iv infusion d1-5. Every course lasted 3-4 weeks. RESULTS: The response rate was 64% (16/25) in treatment group (25 cases) and 34.8% (8/23) in control group (23 cases). The statistic difference was seen in two groups (P< 0.05, Chi-square test). The median survival and 1-year survival rate were 11.5 months and 45.6% for treatment group versus 10.5 months and 36.5% for control group. There was no statistical difference in two groups for overall survival (P >0.05, log-rank test). The main side effects were sensory neuritis in treatment group and nausea vomiting in control group. There were significant statistically differences in two groups (P< 0.05, Wilcoxon rank sum test). The other side effects were similar. CONCLUSION: L-OHP + VP-16 + LV + 5-FU regimen is effective and well tolerable for advanced gastric carcinoma.