Rapid detection of alpha-globin gene αααtriplets with droplet digital PCR / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a rapid method for detection of alpha-globin gene αααbased on droplet digital PCR (ddPCR) technique.</p><p><b>METHODS</b>The differential sequence between the X1 and Y1 box of α1 gene was selected as the amplicon of the target gene with β-actin as the reference gene. The specific primers and TaqMan probes were designed, and then a quantitative method for detecting the copy number was established based on ddPCR technique. The sensitivity and accuracy of the method were evaluated by detecting 28 samples of known genotypes and 60 clinical samples.</p><p><b>RESULTS</b>The ddPCR-based method accurately identified the genotypes of all the 28 samples with known genotypes and detected 5 cases of αα/αααfrom the 60 clinical samples, and the results were verified by MLPA. The sensitivity and accuracy of this method were both 100% for detecting alpha-globin gene ααα.</p><p><b>CONCLUSION</b>This ddPCR-based method for detecting αααtriplet can be applied for population screening and in routine clinical molecular diagnosis with simple operation, rapid analysis and accurate results.</p>

Hemoglobin H disease with a rare α-thalassemia gene mutation (--/αα): pedigree analysis and genetic diagnosis / 南方医科大学学报

<p><b>OBJECTIVE</b>To identify a rare α-thalassemia gene mutation in a family from south China and perform a pedigree analysis and genetic diagnosis of hemoglobin H (HbH) disease caused by this mutation.</p><p><b>METHODS</b>Peripheral blood samples were collected from the family members for analysis of the hematological phenotype and routine test of thalassemia genes. DNA sequencing was carried out for samples that showed genotype and phenotype inconsistency.</p><p><b>RESULTS</b>A rare α-thalassemia *92A>G gene mutation was detected within this family. The proband and his sister were confirmed to have non-deletional HbH disease with α--/αα genotype. The proband's brother was confirmed to have an α-thalassemia trait with the genotype of -α/αα. The proband's father was identified as an α-thalassemia silent carrier with the genotype of αα/αα.</p><p><b>CONCLUSION</b>A rare α-thalassemia *92A>G gene mutation was identified for first time in south China. The description of the basic phenotypic characteristics of α-thalassemia trait and silent carrier caused by this mutation enriches the α-thalassemia gene mutation spectrum in Chinese population and helps in population screening, clinical molecular diagnosis and genetic counseling.</p>

Identification of a missense mutation in SEDL gene from a Chinese family with X-linked spondyloepiphyseal dysplasia tarda / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the SEDL gene mutation in a Chinese family with X-linked spondyloepiphyseal dysplasia tarda (SEDL) and to establish a genotyping assay for rapid diagnosis of this X-linked recessive disorder.</p><p><b>METHODS</b>Clinical diagnoses were made based on physical examination, radiological examination and pedigree analysis for this family. Four primer pairs flanking the SEDL exons 3-6 including their exon/intron boundaries were designed. A rapid genotyping assay based on denaturing high performance liquid chromatography (DHPLC) was established to screen the point mutations of the SEDL gene. Genomic DNA was extracted by standard methods from 18 members in the three generations of the pedigree and subjected to PCR-denaturing high performance liquid chromatography (PCR-DHPLC) assay followed by direct DNA sequencing.</p><p><b>RESULTS</b>A c.218C>T mutation in exon 4 of the SEDL gene, which resulted in a substitution of serine 218 with leucine, was identified in this family. Among the 18 members, 3 patients, 5 obligate female carriers and 2 unmarried young females were found to have the missense mutation, and other 8 healthy individuals were not detected to carry the mutation, in which genotype-phenotype correlations were well established in each member investigated in this family.</p><p><b>CONCLUSION</b>A c.218C>T missense mutation in the SEDL gene was firstly reported in Chinese population and the results of this study expand the spectrum of SEDL mutations. The PCR-DHPLC assay is a useful tool to rapidly detect the SEDL mutation in clinical and prenatal diagnosis.</p>

A community-based genetic screening of large-scale population and prenatal diagnosis for alpha and beta thalassemia in Zhuhai city of Guangdong province / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To describe a community-based model for prevention and control of severe alpha and beta thalassemias in Zhuhai city of Guangdong province.</p><p><b>METHODS</b>Couples for premarital medical examination or regular healthcare examination in pregnancy were enrolled in this prospective screening program, which was supported by the two-level network composed of 6 local hospitals for testing thalassemias and follow-up for genetic counseling. A conventional heterozygote screening strategy was used to determine alpha and beta thalassemia traits in women and their partners according to the standard procedures of hematological phenotype analysis. Then confirmative diagnosis of alpha and beta thalassemia was performed on those couples suspected at-risk for severe thalassemia by using the PCR-based molecular diagnostic assays. The couples at-risk for severe thalassemia were counseled and offered prenatal diagnosis and termination of pregnancy in case of an affected fetus.</p><p><b>RESULTS</b>During the period between January 1998 and December 2005, the screened records included 85522 young females and their partners for premarital screening and 10439 pregnant women for prenatal screening, with 71.38% coverage of total population recorded in this city for premarital screening. Six thousands five hundreds and sixty-three individuals in total were found to be the carriers of thalassemias, with 4312 for alpha thalassemia (4.5%) and 2251 for beta thalassemia (2.3%), respectively. One hundred and forty-eight couples were diagnosed to be at-risk for thalassemias, including 103 for alpha thalassemia and 45 for beta thalassemia, respectively. Successful prenatal diagnosis was made for 142 (98 for alpha thalassemia and 44 for beta thalassemia) out of 148 (95.9%) pregnancies at-risk for severe thalassemias. Twenty-three cases of hydrops fetalis, 4 of Hb H diseases and 14 of beta thalassemia were identified. All 41 pregnancies with affected fetuses were voluntarily terminated. Thus, this has led to a marked decrease of severe thalassemia syndrome since the program started.</p><p><b>CONCLUSION</b>We presented the first community-based prospective screening program in China for control of alpha and beta thalassemia in Zhuhai city with a population of 1.29 million through premarital or prenatal screening. This model could be used for control of thalassemias and other hemoglobinopathies in other regions of China and also in other developing countries.</p>

Diagnostic value of the ratio of ligamentum flavum thickness to oblique diameter of lumbar canal in patients with ligamentum flavum hypertrophy / 中华放射学杂志

Objective To evaluate the diagnostic advantage of the ratio of ligamentum flavum(LF) thickness to oblique canal diameter(TODR)measured on CT images in patients with lumbar canal stenosis. Methods Seventy-one patients underwent CT and MRI examinations respectively,and they were divided into two groups,the positive group and negative group,according to the presence or absence of dural sac notch caused by the LF on bilateral parasagittal MR images.Meanwhile,50 volunteers without any symptom in the lumbar region or legs were examined by CT.TODRs were measured at the L3—S1 levels of the inferior margin of the intervertebral disc on transverse CT images,respectively.The results were further analyzed with the positive findings on MR images,clinical symptoms and physical examination,so as to find out the statistical correlation between them.Results LF thickness was(3.01?0.72)mm and TODR was 0.19?0.04 in the negative group,(3.94?0.84)mm and 0.28+0.06 in the positive group,and(3.16? 0.85)mm and 0.19?0.04 in the control group.There was significant difference between positive group and negative group or control group for LF thickness(P0.24, the sensitivity,specificity and positive predictive value were 74.8%,89.6% and 73.6% respectively. Positive correlation existed between LF thickness or TODR and clinical symptom(r=0.72,0.86,P