Objective To address the quality problems caused by high porosity in the preparation of dental cobalt-chrome alloy prosthetics based on selective laser melting(SLM)technology,we investigated the influence mechanism of different forming process parameters on the microstructure and properties of the materials.Moreover,the range of form-ing process parameters that can effectively reduce defects was precisely defined.Methods The effects of laser power,scanning speed,and scanning distance on the pore properties,surface roughness,and hardness of dental cobalt-chrome al-loy were investigated by adjusting the printing parame-ters in the process of SLM.Through metallographic anal-ysis,image analysis,and molten pool simulation,the pore formation mechanism was revealed,and the relation-ship between the porosity and energy density of SLM dental cobalt-chrome alloy was elucidated.Results When the linear energy density was higher than 0.18 J/mm,the po-rosity defect easily appeared at the bottom of the molten pool.When the laser energy density was lower than 0.13 J/mm,defects occurred in the gap of the molten pool due to insufficient melting of powder.In particular,when the linear energy density exceeded the threshold of 0.30 J/mm or was below 0.12 J/mm,the porosity increased significantly to more than 1%.In addition,we observed a negative correlation between free surface roughness and energy density and an inverse re-lationship between macroscopic hardness and porosity.Conclusion On the basis of the conditions of raw materials and molding equipment used in this study,the key process parameters of SLM of molding parts with porosity lower than 1%were successfully determined.Specifically,these key parameters included the line energy density,which ranged from 0.13 J/mm to 0.30 J/mm,and the scan spacing should be strictly controlled below 90 μm.

OBJECTIVE: To explore the genetic basis for a pedigree affected with X-linked mental retardation. METHODS: The proband was subjected to chromosomal karyotyping, FMR1 mutation testing and copy number variation analysis with a single nucleotide polymorphism microarray (SNP array). His family members were subjected to multiplex ligation-dependent probe amplification (MLPA) assaying. Expression of genes within the repeated region were analyzed. RESULTS: The proband had a normal chromosomal karyotype and normal number of CGG repeats within the FMR1 gene. SNP array identified a 370 kb duplication in Xq28 (ChrX: 153 027 633-153 398 515), which encompassed 14 genes including MECP2. The patient was diagnosed as Lubs X-linked mental retardation syndrome (MRXSL). MLPA confirmed the presence of copy number variation, its co-segregation with the disease, in addition with the carrier status of females. Genes from the duplicated region showed higher levels of expression (1.79 to 5.38 folds) within peripheral blood nucleated cells of the proband. CONCLUSION The patients were diagnosed with MRXSL. The expression of affected genes was up-regulated due to the duplication. Genetic counseling and prenatal diagnosis may be provided based on the results.
DNA Copy Number Variations ; Female ; Fragile X Mental Retardation Protein ; Humans ; Mental Retardation, X-Linked ; Methyl-CpG-Binding Protein 2 ; Pedigree ; Pregnancy

OBJECTIVE: To validate a fetus with high risk for trisomy 13 suggested by non-invasive prenatal testing (NIPT). METHODS: The fetus was selected as the study subject after the NIPT detection at Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences on February 18, 2019. Clinical data of the pregnant woman was collected. Fluorescence in situ hybridization (FISH), chromosomal karyotyping analysis and chromosomal microarray analysis (CMA) were carried out on amniotic fluid and umbilical cord blood and the couple's peripheral blood samples. Copy number variation sequencing (CNV-seq) was also performed on the placental and amniotic fluid samples following induced labor. RESULTS: The pregnant woman, a 38-year-old G4P1 gravida, was found to have abnormal fetal development by prenatal ultrasonography. NIPT test suggested that the fetus has a high risk for trisomy 13. Chromosomal karyotyping analysis of fetal amniotic fluid and umbilical cord blood were 46,XN,add(13)(p10). The result of CMA was arr[hg19]1q41q44(223937972_249224684)×3, with the size of the repeat fragment being approximately 25.29 Mb, the fetal karyotype was thereby revised as 46,XN,der(13)t(1;13)(q41;p10). Chromosomal karyotyping analysis and CMA of the parents' peripheral blood samples showed no obvious abnormality. The CNV-seq analysis of induced placenta revealed mosaicisms of normal karyotype and trisomy 13. The CNV-seq test of induced amniotic fluid confirmed a duplication of chr1:22446001_249220000 region spanning approximately 24.75 Mb, which was in keeping with the CMA results of amniotic fluid and umbilical cord blood samples. CONCLUSION NIPT may yield false positive result due to placenta mosaicism. Invasive prenatal diagnosis should be recommended to women with a high risk by NIPT test. And analysis of placenta can explain the inconsistency between the results of NIPT and invasive prenatal diagnosis.
Humans ; Female ; Pregnancy ; Trisomy 13 Syndrome/genetics* ; DNA Copy Number Variations ; Placenta ; Chromosomes, Human, Pair 1 ; In Situ Hybridization, Fluorescence ; Prenatal Diagnosis/methods* ; Fetus ; Amniotic Fluid ; Chromosome Aberrations ; Trisomy/genetics*

Objective: To investigate the impact of maternal X chromosome aneuploidies on cell free DNA (cf-DNA) prenatal screening. Methods: After genetic counseling, invasive prenatal diagnosis was provided for the 124 cases with high risk of sex chromosome aneuploidie (SCA) indicated by cf-DNA prenatal screening. For cases with discordant results of fetal prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte was collected for copy number variation sequencing (CNV-seq) to detect whether the maternal X chromosome was carrying variations. Results: Totally, 124 cases with high risks of SCA indicated by cf-DNA prenatal screening, 9 cases refused to take invasive prenatal diagnosis, while the remaining 115 cases received. Among the 115 cases, 41 cases received accordant results with cf-DNA prenatal screening while 74 cases discordant. Among the 74 cases with discordant results, 19 cases were indicated with maternal X chromosome variations by maternal leukocyte CNV-seq, which accounting for 25.7% (19/74) of the SCA false positive cases, and 15.3% (19/124) of all SCA cases. Conclusions Pregnant women with X chromosome variations may affect the results of cf-DNA prenatal screening, resulting in false positive or false negative outcomes, it should be emphasized that the cf-DNA results may be affected by maternal X chromosome variations. In cases with discordant results of prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte CNV-seq is recommended to find the reasons of false positive or negative results. And cf-DNA prenatal screening is not recommended for pregnant women who are already known with X chromosome variations.