Analysis on the Genotype of 5018 Cases of Thalassemia in Hunan Area / 中国实验血液学杂志

OBJECTIVE@#To investigate the type and distritution of thalassemia gene mutaitons in Hunan area, so as to provide evidence for prenatal screening, diagnosis and reduction of birth defects.@*METHODS@#A total of 5018 cases from Maternal and Children Health Hospital of Hunan from June 2017 to Dec 2018 were undergone thalassemia gene mutation analysis. The reverse dot blot hydridization was used to detect 6 kinds of genotypes of α-thalassemia and 17 kinds of point mutations of β-thalassemia, and the detected data were analyzed statistically.@*RESULTS@#889 cases (55.9%) of α-thalassemia carriers were found, including 385 cases of silent α-thalassemia, 488 cases of α-thalassemia trait, 16 cases of Hb H disease. --/αα was the most common genotype in α thalassemia. 664 cases (41.7%) were diagnosed as β-thalassemia carriers, heterozygotes accounted for 99.8% (663/664), IVS-Ⅱ-654, CD41-42M and CD17M were the main genotypes, and compound heterozygote accounted for 0.2% (1/664). 38 cases were diagnosed as α-thalassemia combined β-thalassemia.@*CONCLUSION@#The constituent ratio of thalassemia gene mutations in Hunan has regional characteristics, --/αα is the most common genotype in α-thalassemia carrier. IVS-Ⅱ-654, CD41-42 and CD17 are common ones in β-thalassemia. The frequency of α-thalassemia combined with β-thalassemia is high.

Analysis of four fetuses with de novo chromosomal rearrangments using single nucleotide polymorphism microarray chips / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the value of single nucleotide polymophism (SNP) microarray for delineation of de novo chromosomal rearrangements detected upon prenatal diagnosis.</p><p><b>METHODS</b>SNP microarray analysis was carried out for 4 fetuses with de novo sSMCs or balanced reciprocal translocations. Genomic DNA was extracted from cord blood samples, and amplified, tagged and hybridized following the manufacturer's protocol. Data were collected and analyzed.</p><p><b>RESULTS</b>No pathogenic CNVs were detected in fetus A, whose sSMCs was verified to be heterochromatin. Fetus B, who had a de novo mosaic sSMCs, was found to have a 9 Mb duplication in 4p12-q13 which is associated with speech delay and mental retardation. No pathogenic CNVs were detected in fetus C who has 2 translocation chromosomes inherited from its mother and 2 chromosomes derived from a de novo translocation. Fetus D, who had a de novo "balanced" reciprocal translocation, was found to have a 25 Mb duplication in 1q25 and a 17 Mb deletion in 9p22. Cases A and C had normal physical and mental evaluation after birth.</p><p><b>CONCLUSION</b>For its ability to detect cryptic imbalance in de novo sSMCs or balanced reciprocal translocations, SNP-array has provided a powerful aid to conventional karyotype analysis during prenatal diagnosis.</p>

Constructing standard allelic ladders for four short tandem repeat loci and employing them in a population study on Han Nationality of Chengdu in China / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To solve the problems in the accuracy and standardization of short tandem repeats-polymerase chain reaction (STR-PCR) typing, the authors adopted the molecular clone technology in producing the standard allelic ladders of D1S1676, D2S2735, D11S1977 and D22S444 loci and applied them in a population study on the Hans in Chengdu, China.</p><p><b>METHODS</b>PCR was used to produce several different allelic fragments of these loci. PCR products were eluted from the gel and re-amplified by PCR. The purified allelic fragments were then blunt-end subcloned individually into the pGEMR-T plasmid vectors and the recombinant were transfected into competent E.coli DH5alpha TM cells. The results of sequencing confirmed that the size and the construction of the inserts were correct. The recombinant plasmids DNA with the inserts were then used as template for re-amplification to generate the four loci standard ladders.</p><p><b>RESULTS</b>The authors succeeded in producing large quantity of standard allelic ladder of these four loci, with which the genetic polymorphisms of these loci in Chengdu Han population of China were studied.</p><p><b>CONCLUSION</b>This method is of high value for forensic DNA typing to construct standard ladders. D1S1676, D2S2735 loci are robust for forensic analysis in Chinese Han population, whereas the value of D11S1977 and D22S444 loci is limited.</p>