[Clinical features and Y chromosome abnormalities in children with 45, X/46, XY mosaicism]

Objective: To investigate the clinical and genetic characteristics of children with 45, X/46, XY mosaicism. Methods: The retrospective study included 20 children diagnosed with 45, X/46, XY and 45, X/46, X,+mar mosaicism in the First Affiliated Hospital of Zhengzhou University from 2018 to 2022. The clinical features, gonadal pathology, treatment and follow-up were summarized. Genetic tests were performed by SRY gene test, azoospermia factor region (AZF) deletion test, copy number variation-sequencing (CNV-seq). Age at first diagnosis was compared between boys and girls using independent sample t-test. Results: The 20 patients included 3 boys and 17 girls, and the age at first diagnosis were (7.6±5.5) years, it is (2.1±1.9) years in boys, (8.7±5.4) years in girls, significantly younger for boys (t=-3.86, P=0.004). The chief complaint was external genitalia malformation for boys, and short stature (13 cases) and dysplastic external genital for girls (4 cases). Five girls presented with features of Turner syndrome. The gonadal phenotypes included mixed gonadal dysplasia (MGD, 6 cases), complete gonadal dysplasia (CGD, 10 cases), unilateral ovotestis (2 cases), possible ovaries (1 case) and undetermined gonad (1 case). One female with dysplastic genital was reassigned to male, and the gender of the remaining cases remained unchanged. Seven females were treated with recombinant human growth hormone. The height increased by (17±7) cm during the (2.9±1.2) years follow-up. No gonadal malignancy was observed. The karyotype was 45, X/46, XY in 16 cases, and 45, X/46, X,+mar in 4 cases. All of the 4 marker chromosomes were derived from Y chromosome confirmed by CNV-seq. SRY gene was detected in all 20 patients genome, and AZF deletion was found in 7 girls. Conclusions: 45, X/46, XY mosaicism presented with dysplastic external genital or female with remarkable short stature. Gonadal phenotypes included MGD, CGD and ovotestis. AZF microdeletions were found in the majority of female cases.

[Analysis of DMD gene variants in a single center]

Objective: To investigate the DMD genetic variants of the Chinese population with Duchenne (DMD) and Becker muscular dystrophies (BMD). Methods: A cross-sectional study was conducted on 2 690 unrelated patients with DMD and BMD aged 0-18 who visited the Genetic and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University from January 2005 to February 2022. The clinical data, such as gender, age, clinical manifestations, and address, were collected. Multiplex ligation-dependent probe amplification, next generation sequencing panel, Sanger sequencing, and PCR amplification were used to detect the variants of the DMD gene in the patients, whose clinical information and gene detection results were descriptively analyzed. Results: The 2 690 patients included 2 648 males and 42 females, with an age of 6.0 (4.0, 9.0) years. The serum creatine kinase increased in all patients. Pathogenic DMD gene variants were detected in the 2 618 patients, including 1 875 cases (71.6%) large deletions, 231 cases (8.8%) duplications, and 512 cases (19.6%) small variants. Among the deletion variants, the deletion of 3 exons was the most common, accounting for 15.4% (288/1 875); and hotspot deletion involved exons 45 to 50, accounting for 6.3% (119/1 875). Exon 2 was the most common type duplication region, accounting for 13.0% (30/231). Small variants were distributed in all 79 exons of the DMD gene, with no hotspots. In addition, the 46 small variants were previously unreported. Conclusion: Exon deletion is the most common type of DMD gene variant, followed by small variants and exon duplication.

[Novel frameshift mutations in SALL4 in two Chinese families with Okihiro syndrome]

In the present study, clinical manifestations of two Chinese Okihiro syndrome families were analyzed, and genetic detections were performed on the two probands by exome sequencing and verified by Sanger sequencing for family members to determine the biological pathogenesis. Prenatal diagnoses were provided for three high-risk fetuses. The affected members exhibited a wildly spectrum of phenotypes, including ultrasound abnormalities of skeletal system (radius deformity and abnormal posture), and cardiac system (persistent common arterial trunk and ventricular septal defect) in the prenatal period of family 1, the severe phenotypes (grossly shortened and deformed forearm, Duane's anomaly and hearing loss), and the mild ones (usually only thenar dysplasia, or short radius styloid process). Two SALL4 variants, c.844delC p.(Q282Kfs*8) and c.2210delG p.(G737Vfs*23), have been identified respectively in two probands, and c.2210delG of SALL4 gene was unreported previously. The two variants were verified in all affected individuals, not in normal family members. Genotyping results of three fetuses indicated that one fetus was normal, and the two fetuses with heterozygous variation were affected. The two variants of SALL4 gene, c.844delC p.(Q282Kfs*8) and c.2210delG p.(G737Vfs*23), were the molecular pathological cause of Okihiro syndrome in the present study and enriched the spectrum of SALL4 variants. Our study provides accurate prenatal genetic diagnosis for the two families to avoid the birth of affected children.

[Clinical and genetic characteristic in patients with disorders of sex development caused by Y chromosome copy number variant]

Objective: To investigate the clinical phenotype and genetic characteristics of disorders of sex development (DSD) caused by Y chromosome copy number variant (CNV). Methods: A retrospective analysis was performed on 3 patients diagnosed with DSD caused by Y chromosome CNV admitted to the First Affiliated Hospital of Zhengzhou University from January, 2018 to September, 2022. Clinical data were collected. Clinical study and genetic test were performed by karyotyping, whole exome sequencing (WES), low coverage whole genome copy number variant sequencing (CNV-seq), fluorescence in situ hybridization (FISH) and gonadal biopsy. Results: The 3 children, aged 12, 9, 9 years, the social gender were all female, presented with short stature, gonadal dysplasia and normal female external genital. No other phenotypic abnormality was found except for case 1 with scoliosis. The karyotype of all cases were identified as 46, XY. No pathogenic vraiants were found by WES. CNV-seq determined that case 1 was 47, XYY,+Y(2.12) and case 2 was 46, XY,+Y(1.6). FISH concluded that the long arm of Y chromosome was broken and recombined near Yq11.2, and then produced a pseudodicentric chromosome idic(Y). The karyotype was reinterpreted as mos 47, X, idic(Y)(q11.23)×2(10)/46, X, idic(Y)(q11.23)(50) in case 1. The karyotype was redefined as 45, XO(6)/46, X, idic(Y)(q11.22)(23)/46, X, del(Y)(q11.22)(1) in case 2. 46, XY, -Y(mos) was found by CNV-seq in case 3, and the karyotype of 45, XO/46, XY was speculated. Conclusions: The clinical manifestations of children with DSD caused by Y chromosome CNV are short stature and gonadal dysgenesis. If there is an increase of Y chromosome CNV detected by CNV-seq, FISH is recommended to classify the structural variation of Y chromosome.

[Analysis of the factors influencing positive predictive value of noninvasive prenatal testing for chromosome aneuploidies]

Objective: To investigate the influence of Z-score and different risk factors on positive predictive value (PPV) of noninvasive prenatal testing (NIPT) for chromosome aneuploidies. Methods: A total of 81 838 NIPT samples from January 1, 2016 to May 31, 2021 in the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. Invasive prenatal diagnosis was applied to verify the diagnosis of NIPT-positive results and the corresponding PPV was calculated. The PPV of the samples with different Z-score were compared. The women were divided into high-risk group and non-high-risk group: high-risk group (n=39 114) included those with ultrasound soft index abnormalities, advanced maternal age or high risk for maternal serum screening, while non-high-risk group (n=42 724) included those with intermediate risk for maternal serum screening or no indications. The differences of the PPV between these two groups were compared. Finally, the comprehensive influence of Z-score and different risk factors on PPV were analyzed. Results: A total of 471 high-risk cases were detected by NIPT results, including 362 cases of trisomy 21, 77 cases of trisomy 18 and 32 cases of trisomy 13. For trisomy 21, trisomy 18 and trisomy 13, there were 226 cases, 46 cases and 6 cases which were confirmed via invasive prenatal diagnosis respectively. The corresponding PPV were 79.3% (226/285), 82.1% (46/56) and 27.3% (6/22), respectively. PPV of trisomy 21 and trisomy 18 were positively correlated with the corresponding Z-score (r=0.92, 0.62, all P<0.05), while trisomy 13 could not be analyzed due to the small sample size. The PPV of high-risk group was 85.2% (207/243), which was higher than that of the non-high-risk group with PPV of 59.2%(71/120, χ²=30.30, P<0.01). When the Z-score was between 3-<4 and 4-<5, the PPV of the high-risk group were 46.2%(12/26)and 62.5%(15/24) respectively, which were higher than those of the non-high-risk group [16.0%(4/25) and 14.3%(3/21), χ²=4.10, 8.90, all P<0.05]. With the increase of Z-score, there was no significant difference in PPV between the two groups (all P>0.05). Conclusions: The PPV of trisomy 21 and trisomy 18 are positively correlated with Z-score. The PPV of high-risk group is higher than that of non-high-risk group. The combination of Z-score and other risk factors may provide more accurate genetic counseling for those with NIPT positive results.

[Confirmation and analysis of 2 398 positive results of cell-free fetal DNA]

Objective: To explore the clinical application value and accuracy of cell-free fetal DNA (cff-DNA) technique in prenatal screening. Methods: The results of quantitative fluorescent PCR (QF-PCR) and karyotype of amniotic fluid cells were analyzed retrospectively in 2 398 monocyesis pregnant women who had been amniocentesis at the First Affiliated Hospital of Zhengzhou University from May 2013 to December 2019, and the results of 359 cases who had been examined by single-nucleotide polymorphism array (SNP array). Results: Cff-DNA test of 2, 398 cases indicated 987 cases of trisomy 21, 351 cases of trisomy 18, 135 cases of trisomy 13, 566 cases of sex chromosome abnormality, and 359 cases of other chromosome abnormality. Chromosome karyotype analysis detected 826 cases of trisomy 21, 213 cases of trisomy 18, 17 cases of trisomy 13, 221 cases of sex chromosome abnormality, and 26 cases of other chromosome abnormality. The detection rate were 83.69% (826/987), 60.68% (213/351), 12.59% (17/135), 39.04% (221/566) and 7.24% (26/359), respectively. QF-PCR detected 1 046 cases of trisomy and 188 cases of sex chromosomes abnormality, and the detection rate was 99.05% (1 046/1 056) and 85.07% (188/221), respectively. Compared with the abnormal number detected by chromosome karyotype analysis, 10 cases of trisomeric chimerism and 24 cases of sex chromosome were missed by QF-PCR. Among the 359 other chromosomal abnormalities detected by SNP array, 64 cases were consistent with the results of cff-DNA, and the detection rate was 17.83% (64/359), which was 10.59% higher than the karyotype result. Conclusions: Karyotype analysis is the gold standard for diagnosing chromosomal abnormalities. QF-PCR could diagnose common chromosome aneuploidy rapidly and accurately, and it could be used as an auxiliary detection technique for karyotype analysis. The incidence of sex chromosome chimerism is high, so missed diagnosis should be warned. SNP array could be given priority to verify chromosome microdeletion or microduplication detected by cff-DNA.

[Analysis of MYO15A variation in children with DFNB3]

Objective: To analyze the genetic and clinical characteristics of MYO15A variants associated non-syndromic autosomal recessive deafness3 (DFNB3). Methods: The hearing test and high-throughput sequencing data of 108 families with non-syndromic hearing loss, who visited the Center of Genetics and Prenatal Diagnosis in the First Affiliated Hospital of Zhengzhou University from November 2016 to February 2019, were retrospectively analyzed to investigate the characteristics of MYO15A variation. Results: Compound heterozygous MYO15A variations were detected in nine patients from eight families, accounting for 7.4% of all 108 families. The variants were c.5910+1G>A/c.9417_9418insTA, c.4234T>G/c.8324G>T, c.3926A>T/c.5002delC, c.9690+1G>A/c.10257_10259delCTT, c.8324G>T/c.10419_10423delCAGCT, c.4519C>T/c.6454G>C, c.6177+1G>T/c.10257_10259delCTT and c.5692C>T/c.7396-1G>A. All patients had severe to profound hearing loss. Among the 14 variations, 12 variations were located in the main structural domains, including 5 in motor domain, 3 in FERM domain, 3 in MyTH4 domain and 1 in IQ motif. The c.3926A>T, c.4234T>G, c.4519C>T, c.5002delC, c.6454G>C, c.8324G>T, c.9417_9418insTA and c.10419_10423delCAGCT had not been reported in the Human Gene Mutation Database up to February 2020. According to the guidelines of the American College of Medical Genetics and Genomics (ACMG), 6 reported variants and the first reported c.4519C>T, c.5002delC, c.9417_9418insTA and c.10419_10423delCAGCT were identified as pathogenic variants, while c.8324G>T was likely pathogenic variant, and c.3926A>T, c.4234T>G and c.6454G>C were variants of uncertain significance. Conclusions: The variations of MYO15A in patients with DFNB3 are mainly complex heterozygous. The clinical phenotypes are mostly severe to profound hearing loss, and the mutation loci are mainly in the motor, FERM and MyTH4 domains.

[Mutational analysis and prenatal diagnosis of TMPRSS3 gene in two Chinese families affected with deafness]

Objective: To detect potential mutations in two Chinese families affected with deafness, so as provide prenatal diagnosis for them. Methods: Two Chinese families affected with deafness were identified at the genetic and prenatal diagnosis center of the First Affiliated Hospital of Zhengzhou University from March 2018 to December 2018.Mutation analyses were carried out by next generation sequencing (NGS),suspected mutations were verified by Sanger sequencing in the probands, unaffected relatives. Prenatal diagnosis for high-risk fetus were carried out through Sanger sequencing. Results: The proband of family 1 carried a c.432delA and a c.617-2_617-1insTC mutation of the TMPRSS3 gene, the proband of family 2 carried a c.271C>T(p.R91X) and a c.147dupTmutation ofthe TMPRSS3 gene, both parents of the two probands were carriers of heterozygous variants. Conclusions: Mutations in the TMPRSS3 gene are the suspected cause of deafness in two families. Application of next generation sequencing technologies make gene diagnosis of deafness efficiently and accurately and the molecular findings increase our understanding of the function of TMPRSS3 gene and enrich the human gene mutation database. It is helpful for recurrent genetic counseling and prenatal diagnosis for these families.

[Analysis of genetic variation in patients with Waardenburg syndrome type Ⅱ by next generation sequencing]

Objective: To detect gene mutation sassociated with deafness in four Waardenburg syndrome (WS) type Ⅱ patients, and to explore the possible mechanism of molecular genetics. Methods: All patients with WS were identified at the genetic and prenatal diagnosis center of the First Affiliated Hospital of Zhengzhou University from August 2015 to December 2018.Clinical materials and peripheral blood were collected from patients and family members. The genes associated with deafness of the patients were tested by next generation sequencing(NGS). And suspected mutations were verified by Sanger sequencing. Results: All patients carried heterozygous mutations in SOX10, they were c.355_356insTCAGGCAGCGC, c.1106_1107insTGGGGCCCCCCACACTA, c.511T>C (p.Y171H), c.91_100del. According to the guidelines for genetic variation of the Amercian College of Medical Genetics and Genomics (ACMG), three frameshift mutations were pathogenic mutations, one missense mutation was likely pathogenic mutation. Conclusion: Application of next generation sequencing technologies make gene diagnosis of Waardenburg syndrome efficiently and accurately.

[Application of single nucleotide polymorphism array in prenatal diagnosis for fetuses with abnormal ultrasound findings]

Objective: To investigate the value of single nucleotide polymorphism array (SNP-array) for fetuses with abnormal ultrasound findings. Method: A total of 904 fetuses with abnormal ultrasound findings were enrolled in this study from May 2015 to November 2017, and 434 (48.0%) cases received conventional karyotyping analysis at the same time. According to different abnormal ultrasound category, 904 cases were divided into 5 groups: 280 cases (31.0%) in single system structural anomalies, 31 cases (3.4%) in multiple system structural anomalies, 331 cases (36.6%) in single ultrasound soft marker abnormalities without structural anomalies, 107 cases (11.8%) in multiple soft marker abnormalities and 155 cases (17.2%) in structural abnormalities combined with soft markers abnormalities. Abnormal detection rates by SNP-array among 5 groups of abnormal ultrasound category were calculated. Result: (1) Total SNP-array results: 171 (19.0%) cases out of 904 cases analyzed by SNP-array, presented chromosomal abnormalities. Pathogenic copy number variants were detected in 27 cases (3.0%) and variants of unknown significance were detected in 81 cases (7.8%) . In addition, 7 cases (26.0%) were found with new mutation by parental validation. (2) SNP-array of 5 groups: among the 5 groups of abnormal ultrasound category, chromosomal abnormalities were identified by SNP-array in 19.3% (54/280) with single system structural abnormalities, 25.8% (8/31) with multiple system structural abnormalities, 13.9% (46/331) with single nonstructural anomalies, 19.6% (21/107) with multiple nonstructural anomalies and 27.1% (42/155) with structural abnormalities combined with nonstructural anomalies. The differences were significant (P=0.010) . No chromosome abnormalities was identified in single soft marker abnormalities, such as choroid plexus cysts, echogenic foci in the heart, single umbilical artery and pyelectasis. (3) Chromosomal abnormalities: the abnormal detection rate of aneuploidy chromosomal abnormalities by SNP-array increased with the maternal age, decreased with the gestational weeks (all P<0.05) . However, the pathogenic copy number variants and variants of unknown significance rates did not change with maternal age and gestational weeks (all P>0.05) . (4) SNP-array and karyotyping: 434 cases were analyzed by conventional karyotyping and SNP-array respectively, 10.3% (43/419) of which presented chromosomal abnormalities by conventional karyotyping and 18.7% (81/434) of which presented chromosomal abnormalities by SNP-array. Conclusions: SNP-array could be a useful genetic analysis method in prenatal diagnosis for fetuses with abnormal ultrasound findings. For different abnormal ultrasound category, SNP-array has different detection rate. Compared with conventional karyotyping analysis, SNP-array can improve the detection rates for chromosomal abnormalities and find the chromosome abnormalities which can't be detected by conventional karyotyping analysis. In clinical prenatal genetic counseling, SNP-array should be selected rationally in combination with the various abnormal ultrasound category.

[The efficacy of immunoadsorption with Infliximab theraepy on the modulation of disease activity in patients with severe rheumatoid arthritis]

Objective: To evaluated the efficacy of additional immunoadsorption therapy (2 times) besides infliximab (IFX) ondisease remission in patients with severe rheumatoid arthritis (RA). Methods: 90 patients with serve RA were included in this study.There were 43 patients in the control group who were treated with IFX 3 mg/kg+ methotrexate (MTX) therapy, and other 47 patients were experimental group, who were previous given 2 times additional immunoadsorption therapy before IFX 3 mg/kg+ MTX therapy.IFX 3 mg/kg was infused at weeks 0, 2, 6, 14, 22 and 30.Age, sex ration, mean disease duration and core index of disease activity in two treatment groups were collected at weeks 0, 2, 6 and 30 weeks to compare the efficacy and safety of combined immunosorbent therapy in the treatment of severe RA. Results: The baseline age, sex ration and core indexes of disease activity were comparable between the two treatment groups (P>0.05). After treatment, the core indexes of disease activity of all patients decreased significantly compared with their baseline levels (P<0.05) and the difference of sustainable maintenance to 30 weeks (P<0.05). After 2 and 6 weeks of treatment, patients' ACR20 remission rates of the experimental group were 46.81% and 68.08%, significantly higher than the control group; after 30 weeks of treatment, patients' ACR20 remission rates of the experimental group was more than 90%, while the number was 79.07% in the control group.At the same time DAS28-ESR clinical remission and low disease activity also reached 72.34% in the experimental group, higher than the control group(P<0.05). Conclusion: Additional immunoadsorption therapy can rapid relive the disease activity of serve RA patients, and the remission rate of 30W was significantly higher than only IFX treatment.

[Analysis of non-invasive prenatal screening detection in fetal chromosome aneuploidy]

Objective: To evaluate the efficacy of non-invasive prenatal screening (NIPS) in the detection of fetal aneuploidies. Methods: Cell free DNA was sequenced in 5 566 pregnant women to identify the fetal aneuploidies in the First Affiliated Hospital of Zhengzhou University from January 1(st), 2015 to March 15(th), 2016. Among them, 5 230 (93.96%, 5 230/5 566) were singleton pregnancies and 336 (6.04%, 336/5 566) were twin pregnancies. In singleton pregnancies, 1 809 (34.59%, 1 809/5 230) were women with advanced maternal age, and 3 421 (65.41%, 3 421/5 230) were young women. The positive results of NIPS were validated by karyotyping through invasive procedures and neonatal outcomes were followed up by telephone. Results: Among the 5 566 women, 69 (1.24%, 69/5 566) got positive NIPS results, with 66 in singleton pregnancies and 3 in twin pregnancies. Two were monochorionic diamniotic twins and 1 was dichorionic twin pregnancy. The positive predictive value of NIPS for trisomy 21, 18 and 13 were 100.0%, 90.9% and 100.0%, and was 55.6% for sex chromosome aneuploidies. There was no false negative case found during the follow-up. In the advanced maternal age group and young women group, the prevalence rates of fetal chromosomal aneuploidies were 1.11%(20/1 809) and 0.94%(32/3 421), respectively. In the young women with soft markers in fetal ultrasound, the prevalence of fetal chromosomal aneuploidies was 1.44% (7/487), and in serum high risk women, it was 0.94% (7/747). In women with the serum screening risk with cut-off value, 0.89%(9/1 016) had fetal aneuploidies, and the prevalence was 0.77%(9/1 171) in volunteers. There was no statistically significant difference among these groups (P=0.636). Conclusions: There is no difference in the detection rate of fetal aneuploidies between high-risk women in serum screening and volunteers in NIPS. NIPS is more suitable as a first line screening test for women without fetal ultrasound abnormalities. It should be used carefully when there is ultrasound abnormalities.

[Mutation analysis for two hypophosphatasia families with targeted next-generation sequencing]

Objective: To detect the mutations in alkaline phosphatase (ALPL) gene of two Chinese families with perinatal hypophosphatasia (HPP), in order to explore the mechanism of this condition. Methods: Next-generation sequencing (NGS) of osteology system panel was carried out for exome sequencing in the mothers of 2 HPP fetuses, who visited Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University. Further polymerase chain reaction (PCR) and Sanger sequencing validation was performed in the parents, affected fetuses and 200 unrelated healthy individuals to verify the mutation sites. Results: The mother and father of No.1 family carried ALPL gene c. 333delC (p.Gly112AlafsX10) and c. 568_570delAAC (p.190delAsn) base deletions, respectively. The affected fetus carried compound heterozygotes of the two mutations. Two mutations in ALPL gene known to be associated with hypophosphatasia were found in No.2 family, c. 1250A>G (p.Asn417Ser) in the mother and c. 1166C>A (p.Thr389Asn) in the father, while the fetus was a compound heterozygote carrying both of the two mutations. Both families met the pattern of autosomal recessive inheritance. ALPL gene c. 333delC (p.Gly112AlafsX10) was a novel mutation, and it was not found in the 200 unrelated healthy individuals. Conclusions: The mutations in ALPL gene may be the cause of HPP in the 2 families. NGS technology combined with Sanger sequencing could be an efficient and accurate diagnostic method.

[PTPS gene analysis and prenatal diagnosis in patients with 6-pyruvoyl-tetra hydropterin synthase deficiency]

Objective: To analyze the variations of PTPS gene in patients with suspected 6-pyruvoyl-tetra hydropterin synthase deficiency (PTPSD) and to make prenatal diagnosis in high-risk families. Methods: Chemiluminescence was used for phenylalanine detection in blood or dried blood spots.Patients with phenylalanine concentration over 120 μmol/L were detected by urine pterin analysis, and the activity of dihydropteridine reductase (DHPR) was detected. tetrahydrobiopterin loading tests were performed in suspected patients with abnormal urinary pterin profiles. PTPS gene variation analysis was performed by direct Sanger sequencing based on PCR amplification. Prenatal diagnosis in 7 high-risk families was performed by chorionic villus sampling when the genotype was identified. Results: In 656 patients with hyperphenylalanine, 22 cases were diagnosed as PTPSD clinically. 16 variations were detected in the 22 PTPSD cases. The 5 variations, p.Lys77Arg, p.Ile84Phe, c.315-2A>G, c.244-2A>T, c.187-1G>T, were identified as novel variations. Two fetuses carried the same mutation with the proband and therefore were thought to be PTPSD fetuses. Three fetuses carried only one mutant allele and thus were thought to be PTPSD carriers. The other 2 fetuses carried no mutations and were presumed normal. Conclusions: PTPS gene variation analysis is necessary to confirm the diagnosis. Prenatal diagnosis could help avoiding the defect birth in PTPSD families.

[Mutation screening of 433 families with Duchenne/Becker muscular dystrophy]

OBJECTIVE

Mutation analysis of unrelated families with Duchenne/Becker muscular dystrophy (DMD/BMD) was performed to investigate the characteristic of DMD gene mutation, especially the distribution pattern of point mutation of DMD gene in Chinese population.

METHODS

A total of 433 unrelated DMD/BMD families were collected at the Center of Prenatal Diagnosis of the First Affiliated Hospital of Zhengzhou University from March 2010 to December 2014. The deletions or duplications in 79 exons of DMD gene were screened using multiplex ligation-dependent probe amplification (MLPA). Any single-exon deletion detected by MLPA was further validated by PCR amplification. In the 117 unrelated Chinese families in which large-scale deletions and duplications had been excluded by MLPA, the point mutation in 79 exons of DMD gene were tested in the propositus using next-generation sequencing (NGS), and further verified the point mutation using Sanger sequencing.

RESULTS

In the 433 unrelated DMD/BMD families, 316 families with DMD deletions/duplications were identified by MLPA. Out of 57 single-exon deletions detected by MLPA, 3 were found as point mutations by PCR and Sanger sequencing, including 2 nonsense mutation (c.1729G>T [p.Glu577X], c. 3346A>T [p.Lys1116X]) and 1 frame-shift mutation (c.8605_8606delGT [p.Val2869ThrfsX25]). Direct sequencing with Ion PGM and Sanger sequencing in 117 families with negative results in MLPA detected 92 different point mutations in 96 families, including 46 novel mutations, 42 previously reported ones, and 4 possible polymorphisms (rs189143447, rs202008454, rs200213555, rs187617705). The 46 novel mutations consisted of 16 nonsense mutations (c.100A>T [p.Lys34X], c. 1201C>T [p.Gln401X], c. 1707C>A [p.Cys569X], c. 1831G>T [p.Glu611X], c. 1912C>T [p.Gln638X], c. 2213C>G [p.Ser738X], c. 3673_3673delA [p.Ile1225X], c. 3774C>A [p.Cys1258X], c. 4858G>T [p.Glu1620X], c. 5764A>T [p.Lys1922X], c. 6035T>G [p.Leu2012X], c. 6408G>A [p.Trp2136X], c. 7717C>T [p.Gln2573X], c. 7864G>T [p.Glu2622X], c. 8184_8185insT [p.Lys2729X], c. 8215C>T [p.Gln2739X]), 5 missense mutations (c.139G>A [p.Gly47Arg], c. 238G>C [p.Ala80Pro], c. 335G>T [p.Trp112Leu], c. 804A>C [p.Leu268Phe], c. 1149G>T [p.Glu383Asp]), 6 splice-site mutations (c.2293-3C>A, c. 2380+ 1G>T, c. 3277-1G>C, c.4519-7A>G, c. 5740-15G>T, c. 7661-1G>C), 16 small deletions (c.688_688delA [p.Met230CysfsX14], c.1760_1791del32 [p.Thr587IlefsX37], c. 2271_2271delA [p.Asp774ThrfsX22], c. 2281_2285delGAAAA [p.Glu761SerfsX10], c. 2527_2527delG [p.Glu843SerfsX3], c. 3405_3405delC [p.Asn1135LysfsX18], c. 4450_4450delC [p.His1484ThrfsX14], c. 4770_4770delA [p.Thr1590ThrfsX5], c. 4937_4937delA [p.Glu1646GlyfsX11], c. 5253_5256delATTA [p.Lys1751LysfsX2], c. 5654_5654delA [p.Gln1885ArgfsX6], c. 7441_7441delG [p.Glu2481AsnfsX13], c. 7860_7860delC [p.Ile2620IlefsX18], c. 8668-8668delG /c.8668+ 1-8668+ 1delG, c. 9009_9009delC [p.Thr3003ThrfsX18], c. 9021_9021delT [p.Ile3007IlefsX14]), and 3 small insertions (c.305_306insG [p.Gly102GlyfsX4], c. 3116_3117insA [p.His1039GlufsX11], c. 9197_9198insATCTC [p.Ser3066SerfsX25]). And 87.4% (83/95) of the pathologic point mutations disrupted the translational reading frame (46 nonsense mutations, 24 frame-shift mutations, and 13 splice-site mutations).

CONCLUSIONS

Inexpensive and efficient genetic/prenatal diagnosis of DMD/BMD may be plausible by MLPA analysis, NGS, and Sanger sequencing. Most of the mutations identified in this study led to a predictable premature stop codon or splicing defects, resulting in defective function of dystrophin.

[PAX3 gene mutation analysis for two Waardenburg syndrome type Ⅰ families and their prenatal diagnosis]

Objective: To analyze the mutations of PAX3 gene in two Waardenburg syndrome type Ⅰ (WS1) pedigrees and make prenatal diagnosis for the high-risk 18-week-old fetus. Methods:PAX3 gene was first analyzed by Sanger sequencing and multiplex ligation-dependent probe amplification(MLPA) for detecting pathogenic mutation of the probands of the two pedigrees. The mutations were confirmed by MLPA and Sanger in parents and unrelated healthy individuals.Prenatal genetic diagnosis for the high-risk fetus was performed by amniotic fluid cell after genotyping. Results: A heterozygous PAX3 gene gross deletion (E7 deletion) was identified in all patients from WS1-01 family, and not found in 20 healthy individuals.Prenatal diagnosis in WS1-01 family indicated that the fetus was normal. Molecular studies identified a novel deletion mutation c. 1385_1386delCT within the PAX3 gene in all affected WS1-02 family members, but in none of the unaffected relatives and 200 healthy individuals. Conclusions:PAX3 gene mutation is etiological for two WS1 families. Sanger sequencing plus MLPA is effective and accurate for making gene diagnosis and prenatal diagnosis.

Biocompatible Fibroin Blended Films with Recombinant Human-like Collagen for Hepatic Tissue Engineering

Recombinant human-like collagen (RHLC) was blended with fibroin to prepare a novel biocompatible film as a scaffold material for hepatic tissue engineering applications. Solution blending was used to incorporate RHLC with silk fibroin to enhance the blend films biocompatibility and hydrophilicity while maintaining elasticity. FTIR and XRD analysis indicated that hydrogen bonds had formed between fibroin and RHLC, while SEM microscopy data confirmed that homogeneous microstructures were still retained after the introduction of RHLC with fibroin. Contact angle measurements indicated that the hydrophilicity of the fibroin/RHLC films was greater after RHLC was added. The elongation at break in the wet state was not markedly changed after blending the recombinant human-like collagen, which implied that flexibility was maintained. The proliferation and viability of the cell cultures on fibroin/RHLC films were significantly enhanced compared to pure fibroin films or tissue culture plates.

Mutation analyses and prenatal diagnosis in families of X-linked severe combined immunodeficiency caused by IL2Rγ gene novel mutation

We investigated the feasibility of interleukin-2 receptor gamma (IL2Rγ) gene based on gene mutation analysis and pre-natal diagnosis of X-linked severe combined immunodeficiency (X-SCID). Blood samples of patients and their parents of X-SCID (family 1) and X-SCID (family 2) were collected. IL2Rγ gene sequences of the 2 families were analyzed using bi-directional direct sequencing by polymerase chain reaction. DNA sequence changes in the IL2Rγ gene exon region and shear zone were also analyzed. We also sequenced the IL2Rγ gene in 100 healthy individuals. Prenatal genetic diagnoses for a high-risk fetus in family 1 were performed by chorionic villus sampling after determining each family's genotypes. The suspect fe-male in family 1 underwent carrier detection. Two novel mutations of IL2Rγ gene were identified, including c.361-363delGAG (p.E121del) in the patient and his mother in family 1, and c.510-511insGAACT (p.W173X) heterozygous mutation in the proband's mother in family 2. These mutations were absent in the 100 controls. Prenatal diagnosis of early pregnancy in the female fetus of family 1 was performed; the fetus was heterozygous, which was confirmed at postnatal follow-up. The suspect female in family 1 showed no mutation in carrier detection. The novel p.E121del and p.W173X mutations in IL2Rγ may have been the primary causes of disease in 2 families with X-SCID. In couples with an X-SCID reproductive history, prenatal gene mutation analysis of IL2Rγ can effectively prevent the birth of children with X-SCID and carrier detection for suspected females.

Mutation analysis and prenatal diagnosis for three families affected by isolated methylmalonic aciduria

Isolated methylmalonic acidemia (MMA) is a genetically heterogeneous disorder caused mainly by deficiency of methylmalonyl-CoA mutase. In the present study, we analyzed MUT gene mutations in 3 Chinese couples with a birth history of isolated MMA. We also provided prenatal diagnoses for the detected mutation. Exons and exon-intron boundaries of the MUT gene were analyzed by polymerase chain reaction and direct sequencing. Prenatal genetic diagnoses were performed by chorionic villus sampling after the genotypes of parents were determined. Six heterozygous mutations in the MUT gene were identified in the 3 families, including c.1880A>G (p.H627R) and IVS9-1G>A for family 1, c.1741C>T (p.R581X) and c.729insTT (p.D244fX39) for family 2, and c.616C>T (p.Q206X) and c.1280G>A (p.G427D) for family 3. Among these, c.616C>T (p.Q206X), c.1280G>A (p.G427D), IVS9-1G>A, and c.1741C>T (p.R581X) were novel mutations. These mutations were not detected in 100 normal controls. The fetus in pedigree 3 was free of the mutations carried by the parents, while the fetuses in pedigrees 1 and 2 were heterozygous mutation carriers. All 3 families decided to continue with their pregnancies and the neonates did not show any symptoms of MMA after birth. Our results indicated that mutations in the MUT gene are the primary cause of isolated MMA, and that most mutations were novel. For families with early-onset isolated MMA, direct sequencing of the MUT gene is crucial for genetic counseling, prenatal diagnosis, and identification of carriers.

Bioinformatics analysis of biomarkers and transcriptional factor motifs in Down syndrome

In this study, biomarkers and transcriptional factor motifs were identified in order to investigate the etiology and phenotypic severity of Down syndrome. GSE 1281, GSE 1611, and GSE 5390 were downloaded from the gene expression ominibus (GEO). A robust multiarray analysis (RMA) algorithm was applied to detect differentially expressed genes (DEGs). In order to screen for biological pathways and to interrogate the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database, the database for annotation, visualization, and integrated discovery (DAVID) was used to carry out a gene ontology (GO) function enrichment for DEGs. Finally, a transcriptional regulatory network was constructed, and a hypergeometric distribution test was applied to select for significantly enriched transcriptional factor motifs. CBR1, DYRK1A, HMGN1, ITSN1, RCAN1, SON, TMEM50B, and TTC3 were each up-regulated two-fold in Down syndrome samples compared to normal samples; of these, SON and TTC3 were newly reported. CBR1, DYRK1A, HMGN1, ITSN1, RCAN1, SON, TMEM50B, and TTC3 were located on human chromosome 21 (mouse chromosome 16). The DEGs were significantly enriched in macromolecular complex subunit organization and focal adhesion pathways. Eleven significantly enriched transcription factor motifs (PAX5, EGR1, XBP1, SREBP1, OLF1, MZF1, NFY, NFKAPPAB, MYCMAX, NFE2, and RP58) were identified. The DEGs and transcription factor motifs identified in our study provide biomarkers for the understanding of Down syndrome pathogenesis and progression.

Enhancement of the activity of l-aspartase from Escherichia coli W by directed evolution

l-Aspartase was modified by directed evolution. After four rounds of error-prone PCR and three rounds of DNA shuffling, an evolved enzyme purified from the final round showed a 28-fold increased k(cat)/K(m) and 4.6-fold decreased K(m). The thermostability and stable pH range were also enhanced. The DNA sequence of the evolved aspartase gene showed seven base changes, resulting in three amino acid changes from the native enzyme: N217K, T233R, V367G. The mechanism of the enhancement of activity was analyzed.