Noninvasive prenatal testing for the detection of fetal chromosome 17 microduplication: clinical implications and findings.

BACKGROUND:  Noninvasive prenatal testing (NIPT) is widely used to screen for fetal aneuploidies. However, there are few reports of using NIPT for screening chromosomal microduplications and microdeletions. This study aimed to investigate the application efficiency of NIPT for detecting chromosomal microduplications. METHODS: Four cases of copy number gains on the long arm of chromosome 17 (17q12) were detected using NIPT and further confirmed using copy number variation (CNV) analysis based on chromosome microarray analysis (CMA). RESULTS: The prenatal diagnosis CMA results of the three cases showed that the microduplications in 17q12 (ranging from 1.5 to 1.9 Mb) were consistent with the NIPT results. The karyotypic analysis excluded other possible unbalanced rearrangements. The positive predictive value of NIPT for detecting chromosomal 17q12 microduplication was 75.0%. CONCLUSIONS:  NIPT has a good screening effect on 17q12 syndrome through prenatal diagnosis, therefore it could be considered for screening fetal CNV during the second trimester. With the clinical application of NIPT, invasive prenatal diagnoses could be effectively reduced while also improving the detection rate of fetal CNV.

Luteolin induces hippocampal neurogenesis in the Ts65Dn mouse model of Down syndrome.

Studies have shown that the natural flavonoid luteolin has neurotrophic activity. In this study, we investigated the effect of luteolin in a mouse model of Down syndrome. Ts65Dn mice, which are frequently used as a model of Down syndrome, were intraperitoneally injected with 10 mg/kg luteolin for 4 consecutive weeks starting at 12 weeks of age. The Morris water maze test was used to evaluate learning and memory abilities, and the novel object recognition test was used to assess recognition memory. Immunohistochemistry was performed for the neural stem cell marker nestin, the astrocyte marker glial fibrillary acidic protein, the immature neuron marker DCX, the mature neuron marker NeuN, and the cell proliferation marker Ki67 in the hippocampal dentate gyrus. Nissl staining was used to observe changes in morphology and to quantify cells in the dentate gyrus. Western blot assay was used to analyze the protein levels of brain-derived neurotrophic factor (BDNF) and phospho-extracellular signal-regulated kinase 1/2 (p-ERK1/2) in the hippocampus. Luteolin improved learning and memory abilities as well as novel object recognition ability, and enhanced the proliferation of neurons in the hippocampal dentate gyrus. Furthermore, luteolin increased expression of nestin and glial fibrillary acidic protein, increased the number of DCX+ neurons in the granular layer and NeuN+ neurons in the subgranular region of the dentate gyrus, and increased the protein levels of BDNF and p-ERK1/2 in the hippocampus. Our findings show that luteolin improves behavioral performance and promotes hippocampal neurogenesis in Ts65Dn mice. Moreover, these effects might be associated with the activation of the BDNF/ERK1/2 pathway.

Noninvasive prenatal screening for fetal common sex chromosome aneuploidies from maternal blood.

Objective To explore the feasibility of high-throughput massively parallel genomic DNA sequencing technology for the noninvasive prenatal detection of fetal sex chromosome aneuploidies (SCAs). Methods The study enrolled pregnant women who were prepared to undergo noninvasive prenatal testing (NIPT) in the second trimester. Cell-free fetal DNA (cffDNA) was extracted from the mother's peripheral venous blood and a high-throughput sequencing procedure was undertaken. Patients identified as having pregnancies associated with SCAs were offered prenatal fetal chromosomal karyotyping. Results The study enrolled 10 275 pregnant women who were prepared to undergo NIPT. Of these, 57 pregnant women (0.55%) showed fetal SCA, including 27 with Turner syndrome (45,X), eight with Triple X syndrome (47,XXX), 12 with Klinefelter syndrome (47,XXY) and three with 47,XYY. Thirty-three pregnant women agreed to undergo fetal karyotyping and 18 had results consistent with NIPT, while 15 patients received a normal karyotype result. The overall positive predictive value of NIPT for detecting SCAs was 54.54% (18/33) and for detecting Turner syndrome (45,X) was 29.41% (5/17). Conclusion NIPT can be used to identify fetal SCAs by analysing cffDNA using massively parallel genomic sequencing, although the accuracy needs to be improved particularly for Turner syndrome (45,X).

The significance of F139V mutation on thrombotic events in compound heterozygous and homozygous protein C deficiency.

Both compound heterozygous and homozygous protein C deficiencies (PCDs) can cause lethal thrombotic events in children. This study investigated the significance of F139V mutation in activation of protein C in heterozygous and biallelic PCD. Two pedigrees with three probands were recruited, including heterozygous, compound heterozygous, and homozygous PCD and non-PCD families. The plasma levels of protein C activity (PC:A), protein C antigen (PC:Ag), factor V:C, factor VIII:C, fibrinogen (FIB), and D-dimer (D-D) were measured. Prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) were also detected. All nine exons of protein C gene (PROC) were sequenced. Protein C mutation, T>G at site 6128 (exon 7) resulting in F139V, was identified in both pedigrees. Heterozygous missense mutation F139V (n = 10) had 56.4% lower levels of PC:A and PC:Ag compared with members with wild-type PROC (n = 6). Biallelic compound heterozygous and homozygous PCDs with F139V (n = 3) significantly decreased the levels of PC:A and PC:Ag compared with heterozygous members (P < 0.05); however, these were not lethal. Heterozygous F139V mutations of PRO caused mild reduction of protein C function, which might be the reason for survival of compound heterozygous or homozygous PCD with F139V in adults.

[Analysis of an hereditary protein C deficiency pedigree with compound heterozygous gene mutations].

OBJECTIVE: To analyze genetic mutations and explore its molecular pathogenesis for an hereditary protein C (PC) deficiency pedigree. METHODS: The pedigree has included 15 individuals from 4 generations. Plasma levels of PC activity (PC:A), PC antigen (PC:Ag) and other coagulant parameters were determined for members of the family. The 9 exons and intron-exon boundaries of protein C gene (PROC) of the proband were amplified with PCR and analyzed with direct sequencing. Detected mutations were confirmed with reverse sequencing. Corresponding PCR fragments from the family members were also directly sequenced. RESULTS: Plasma PC:A and PC:Ag for the proband was 26% and 18.60%, respectively, both being lower than normal references. Seven members from the pedigree also had lower PC:A, six had lower PC:Ag. A compound heterozygous missense mutation, including a T to G transition at position 6128 of exon 7, which results in Phe139Val, and a G to C transition at position 8478 in exon 9, which results in Asp255His, were identified in the proband. The paternal grandma, father and two aunts were heterozygous for g.6128 T to G, whilst the mother, the second uncle, sister and son were heterozygous for g.8478 G to C. There were lower PC:A in family members with g.8478 G to C. CONCLUSION: The proband had inherited two independent mutations of the PROC gene including g.6128 T to G in exon 7 and g.8478 G to C in exon 9 from her father and mother, respectively. The resulting compound heterozygous mutation has caused a serious hereditary protein C deficiency.

[Molecular genetics and clinical features of nine patients with inherited coagulation factor VII deficiency].

OBJECTIVE: To investigate potential mutations and clinical features of 9 unrelated patients with inherited coagulation factor VII (FVII) deficiency. METHODS: Clinical diagnosis was validated by assaying of coagulation parameters including prothrombin time, activated partial thromboplastin time, FVII activity and specific antigens. All exons, exon-intron boundaries, and 5' and 3' untranslated regions of F7 genes were amplified with PCR. Potential mutations were detected by direct sequencing of purified PCR products. Suspected mutations were confirmed by sequencing of the opposite strand. RESULTS: All probands have featured prolonged prothrombin time, with FVII activity ranging between 2.0% to 6.0%. The titers of FVII antigen were significantly reduced in 7 probands. Eight mutations, including 6 missense mutations, 1 deletion and 1 insertion, were identified, among which 3 (Gln100Leu, Ser269Pro and g.11520_11521insT) were not described previously. Six mutations have located in the protease domain. All mutations were inherited, and consanguineous marriages were reported in 5 families. Mutations g.27_28delCT, Cys329Gly, Arg304Trp and His348Gln have been identified in unrelated families. There was a lack of correlation between the mutations and their clinical features. Two individuals with homozygous His348Gln mutations and 1 individual with homozygous Arg304Trp mutation were only mildly affected or asymptomatic. Two patients, who have respectively carried homozygous and heterozygous deletions of g.27_28delCT, were moderately affected and asymptomatic. In 4 patients carrying double heterozygous mutations, 1 (Ser269Pro and Cys329Gly) was asymptomatic, 2 (Arg304Trp and Cys329Gly, Arg277Cys and g.11520_11521insT, respectively) had a mild bleeding tendency, whilst 1 (Gln100Leu and His348Gln) has a moderate bleeding diathesis. CONCLUSION: There seem to be hotspots of F7 gene mutations in ethnic Han Chinese populations. And there is a lack of correlation between particular types of mutations and clinical phenotypes.

[Analysis of an hereditary coagulation factor XII deficiency in a consanguineous pedigree].

OBJECTIVE: To analyze genetic mutation and explore its molecular pathogenesis for an hereditary coagulation factor XII(F XII) deficiency in a pedigree featuring consanguineous marriage. METHODS: Activated partial thromboplastin time (APTT), F XII procoagulant activity (F XII:C), F XII antigen (F XII:Ag) and other coagulant parameters were assayed. For the proband and his family members, exons 1-4, introns including the splice junctions of the F XII gene were amplified with polymerase chain reaction (PCR). The PCR product was purified and sequenced. The mutations were confirmed by sequencing the complimentary strand. RESULTS: The proband has featured prolonged APTT at 157.5 s (reference range, 27.0-41.0 s). The APTT of his son has increased slightly at 48.3 s. The remaining members of the family were in normal range. F XII activity and F XII antigen of the proband were significantly decreased (<1%). The F XII activity of his wife, daughter, son and mother was also dropped to about 51%, 21%, 21% and 50%, respectively, and so was the F XII antigen (42%, 32%, 37% and 48%, respectively). Homozygous missense mutation of G→A transition at position 8699 in exon 14 resulting in Gly542Ser was identified in the proband. His mother, son and daughter were heterozygous for Gly542Ser. In the promoter regions of F XII gene, the genotype of the proband and the other members was 46T/T. CONCLUSION: Homozygous missense mutation Gly542Ser was found in a pedigree of hereditary F XII deficiency. The homozygous missense mutation might have resulted from his parents by consanguineous marriage. Gly542Ser and 46T/T have contributed to the pathogenesis of the hereditary factor XII deficiency pedigree.

[Gene analysis of a combined inherited factor VII and factor X deficiency pedigree].

OBJECTIVE: To perform gene analysis and family survey of a patient with combined inherited FVII and FX deficiency, and to identify the gene mutation of this patient. METHODS: The phenotype diagnosis was validated by coagulant parameter assay on prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, FVII and FX activity (FVII:C, FX:C) and FVII and FX antigen (FVII:Ag, FX:Ag). FVII and FX gene mutations were analyzed in the proband and other family members by DNA direct sequencing of all exons, exon-intron boundaries and 5', 3' untranslated sequences. One hundred and six health examination participants were selected as control. RESULTS: The values of PT and APTT of the proband showed significantly prolonged, which were 84.5s and 63.4s, respectively. The levels of FVII:C, FVII:Ag, FX:C and FX:Ag were 6%, 7%, 4% and 30%, respectively. The PT of his father, mother and sister was prolonged slightly while both APTT and FVII:Ag were in the normal range. Two homozygous mutations, g.11267C→T in exon 8 of FVII gene resulting in the substitution of Arg277Cys and g.28139G→T in exon 8 of FX gene leading to the substitution of Val384Phe, were identified in the proband. The proband's parents and sister were heterozygous for Arg277Cys and Val384Phe mutations. CONCLUSION: Homozygous mutation Arg277Cys in FVII gene and Val384Phe in FX gene were the molecular mechanism causing combined inherited FVII and FX deficiency. The Val384Phe substitution was a novel mutation, which may affect the synthesis or secretion of FX protein.