Novel Homozygous Nonsense Mutation Associated with Bardet-Biedl Syndrome in Fetus with Congenital Renal Malformation

Background: Bardet-Biedl syndrome (BBS) is a rare autosomal recessive genetic disorder with clinical and genetic heterogeneity. BBS is more commonly reported in adults and children than in fetuses. Method: Here, a retrospective study of 210 fetuses with congenital renal malformation was performed. These fetuses were performed invasive prenatal diagnosis. Chromosome karyotype analysis, whole exome sequencing (WES), and a single nucleotide polymorphism array (SNP-array) were used.Results: We found the intrauterine phenotype of a fetus with enlarged kidneys, enhanced echo, and oligohydramnios, and the molecular characterizations of the fetus with BBS. The results of chromosome karyotype analysis and SNP-array on the fetus were normal. WES, however, revealed homozygous mutation of c.1177C>T (p.Arg393*) on exon 12 of the BBS1 gene, and heterozygous variation of c.2704G>A (p.Asp902Asn) on exon 22 of the CC2D2A gene. According to ACMG guidelines, c.1177C> T was identified as a pathogenic mutation and c.2704G>A was identified as an uncertain significance. Sanger sequencing showed that there was heterozygous mutation of c.1177C>T and heterozygous variation of c.2704G>A in the parents of the fetus. Conclusion: WES identified a novel homozygous nonsense mutation c.1177C>T in the BBS1 gene of a Chinese fetus with congenital renal malformation. The finding provides more insight into BBS1 mutations in Asian populations in general, and provides a basis for genetic counseling.

Identification of a Novel Homozygous Nonsense Mutation in a Fetus with Bardet-Biedl Syndrome

Background: Bardet-Biedl syndrome (BBS) is a rare autosomal recessive genetic disorder with clinical and genetic heterogeneity. BBS is more commonly reported in adults and children than in fetuses. Here, we reported the intrauterine phenotype and molecular characterizations of a fetus with BBS. Methods: Chromosome karyotype analysis, whole exome sequencing (WES), and a single nucleotide polymorphism array (SNP-array) were used to analyze the genetic etiology of a fetus with enlarged kidneys, enhanced echo, and oligohydramnios. Results: The results of chromosome karyotype analysis and SNP-array on the fetus were normal. WES, however, revealed homozygous mutation of c.1177C>T (p.Arg393*) on exon 12 of the BBS1 gene, and heterozygous variation of c.2704G>A (p.Asp902Asn) on exon 22 of the CC2D2A gene. According to ACMG guidelines, c.1177C> T was identified as a pathogenic mutation and c.2704G>A was identified as an uncertain significance. Sanger sequencing showed that there was heterozygous mutation of c.1177C>T and heterozygous variation of c.2704G>A in the parents of the fetus. Conclusions: WES identified a novel homozygous nonsense mutation c.1177C>T in the BBS1 gene of a Chinese fetus. The finding provides more insight into BBS1 mutations in Asian populations in general, and provides a basis for genetic counseling.

Prenatal Diagnosis and Prognosis of Fetal Hyperechogenic Kidney: A Study of 80 Cases

Background Prenatal diagnosis of fetal hyperechogenic kidney poses a challenge. The aim of this study was to investigate the genetic reasons and prognosis of fetal hyperechogenic kidney diagnosed on prenatal ultrasonography. Methods We retrospectively reviewed the clinical data of 80 cases of prenatally diagnosed fetal hyperechogenic kidney by the obstetric ultrasound. The genetic characteristics and pregnancy outcomes were analyzed using chromosome karyotype analysis, chromosome microarray analysis, and whole-exome sequencing. Results Of the 80 cases, 48 (60%) were those of isolated fetal hyperechogenic kidney and 32 (40%) were those of non-isolated cases, including 4 cases (5%) of urinary system abnormalities, 7 (8.75%) of central nervous system abnormalities, 5 (6.25%) of cardiac abnormalities, and 16 (20%) of multiple abnormalities. Chromosome karyotype analysis and microarray analysis revealed 17 (21.25%) abnormalities, including isolated fetal hyperechogenic kidney (9, 11.25%) and chromosome microdeletion microduplication (17q12 microdeletion syndrome, Williams-Beuren syndrome, 4p16.3-p16.1 microduplication syndrome) (8, 10%). Moreover, 9 patients had single gene mutations, including those of BBS2, BBS7, HNF1B, ACE, CEP290, COL4A5, and PKHD1. Total 48 pregnancies were terminated (57.3%), and the remaining 32 fetuses survived and grew normally, the neonatal renal function tests were normal. Conclusions Fetal hyperechogenic kidney chromosome abnormalities are common, in particular, there is considerable prevalence of isolated fetal hyperechogenic kidney. Therefore, advances in prenatal diagnosis are crucial, if necessary, with the combined use of whole-exome sequencing and other comprehensive detection methods.

Combined Application of Chromosome Karyotype and Microarray Analysis in Fetus With Increased Nuchal Translucency

Objective：To examine the risk of chromosomal abnormalities when the thickness of the nuchal translucency( NT ) is 2.5-2.9mm, to evaluate the cutoff value of NT for prenatal diagnosis, to explore the value of combined application of chromosome karyotype and microarray analysis, and to explore the relationship between NT ≥ 5.0mm and fetal prognosis. Methods：A total of 366 pregnant women who underwent prenatal diagnosis in Anhui Province Maternity and Child Health Hospital from January 2018 to August 2020 were collected, of which 241 cases had NT ≥ 2.5mm, 125 cases were elderly (35-38 years old) with NT < 2.5mm. We made grouping statistics on chromosome abnormalities,and compared the detection of chromosome abnormalities by karyotype and microarray analysis. At the same time, we followed up the fetuses with NT ≥ 5.0mm and analyzed their prognosis. Results: (1)Among the 366 cases with NT thickening,the detection rates of chromosome abnormalities by karyotype analysis and microarray analysis(CMA) were 13.39% (49/366) and 13.93% (51/366), respectively, and there was no significant difference (P>0.05), including 25 cases of trisomy 21, 5 cases of trisomy 18, 5 cases of Turner synthesis and 16 cases of other chromosome abnormalities. (2)We compared the effect of different NT value on the detection rate of pathogenic chromosomes, and found that the difference between NT ≥2.5mm and NT < 2.5mm was statistically significant(P<0.05). The detection rates of pathogenic chromosomal abnormalities in NT < 2.5mm group,2.5-2.9mm group, 3.0-3.4mm group,3.5-4.4mm group,4.5-5.4mm group and NT ≥ 5.5mm group were 0.8%(1/ 125), 11.63%(10/ 86), 17.81%(13/ 73), 20%(10/ 49), 47.62%(10/ 21) and 63.64%(7/ 11) respectively. (3)Our study found that different prenatal diagnostic indicators for abnormal chromosome detection rate difference was statistically significant(P<0.05). The detection rates of NT thickening alone and NT thickening combined with other abnormalities were 13.17%(22/ 167) and 35.14%(26/ 74) respectively(P<0.05). (4)Among 18 pregnant women with NT ≥ 5.0 mm, 9 fetuses were chromosomal abnormalities, and 9 fetuses survived healthily. Conclusions：When the NT value is 2.5-2.9mm, the incidence of fetal chromosome abnormality is significantly higher than that in the normal group. It is suggested that invasive prenatal diagnosis should be performed for pregnant women with NT ≥ 2.5mm. Chromosome karyotype analysis and CMA can complement each other, which is conducive to prenatal genetic counseling. The fetuses with NT thickening usually have good pregnancy outcomes when excluding fetal chromosome and prenatal ultrasound does not indicate any abnormalities.

Chromosome Karyotype and Stability Identification of New Synthetic Hexaploid Wheat

Synthetic hexaploid wheats offer breeder ready access to potentially novel genetic variations in wild ancestral species. In present study, we used MY3478 (2n = 4x = 28, AABB) as female crossing with SY41 (2n = 2x = 14, DD) of stripe rust resistant as male through natural chromosome doubling to constructed the new hexaploid wheat line NA0928. Agronomic traits and cytological analysis were characterized in NA0928 of S8-S9 generations. The major study and results were described as follows, agronomic character variation coefficient in NA0928 of S8 generation showed that the effective tiller number (55.3%) > spike length (15.3%) > number of spikelets (13.9%) > plant height (8.7). It is suggested that the effective tiller number and spike length have great utilization value in breeding. Cytological observation and fluorescence in situ hybridization (FISH) results showed that the chromosome number and configuration have rich variations in S9 of NA0928. Chromosome number variation range of 36–44. Numerous chromosome karyotype variations were almost detected in A and B subgenomes. In addition, more diverse types of chromosomal structure variations were observed in the stripe rust resistant strains with more excellent performance than susceptible strains in agronomic traits. Especially, the tillering number of the resistant strains were much higher. Here, Meiosis stage of pollen mother cells and multicolor-GISH (Mc-GISH) results showed that two new synthetic hexaploid wheat lines were obtained, which showed genetic stability, one line was resistance to stripe rust, and the other one line was susceptible stripe rust, at the same time, there had two excellent characteristics with high 1000-grain weight and multiple tillers. They will be valuable germplasm materials in wheat breeding utilization.

Chromosomal Characteristics and Prognostic Analysis of Secondary Acute Myeloid Leukemia

BackgroundSecondary Acute Myeloid Leukemia (S-AML) patients generally have a poor prognosis, and the chromosomal karyotype of S-AML have been rarely reported in the published literature. We aimed to explore the chromosomal karyotype and its clinical significance in patients with S-AML.MethodsClinical characteristics and chromosome karyotypes of 26 patients with S-AML were retrospectively analyzed. The overall survival (OS) was measured from the time of the patients’ transition to AML (which means the time of S-AML diagnosis) .ResultsAmong the 26 S-AML patients, there were 13 males and 13 females, with a median age of 63 years old (range, 20-77 years old). All of them were secondary to a variety of hematologic malignancies or solid tumors, and most of them were secondary to myelodysplastic syndrome (MDS). About 62% of the S-AML patients showed chromosome abnormalities. The level of serum lactate dehydrogenase (LDH) in S-AML patients with abnormal chromosome karyotype was higher than those with normal chromosome karyotype. Apart from the differences in treatment regimens, S-AML patients with chromosomal karyotype abnormalities had shorter OS (P<0.05). ConclusionsS-AML patients with abnormal chromosomal karyotype have higher LDH and shorter OS than normal chromosomal karyotype, and the OS of hypodiploidy was much shorter than hyperdiploid.

Application values of prenatal screening and non‑invasive gene sequencing in fetal birth defects

Objective: To investigate effects of prenatal screening and non-invasive gene sequencing on the clinical diagnosis of fetal birth defects and the outcome of pregnancy. Methods: Totally 2520 pregnant women who received prenatal screening in our hospital were selected as the research subjects. The high-risk pregnant women were further tested by the non-invasive gene sequencing technology. Pregnant women with positive results were diagnosed by amniocentesis and fetal chromosome karyotype analysis, and the pregnancy outcome was followed up for one year. Results: 870 out of the 2520 pregnant women was tested by non-invasive gene sequencing technology; 26 of the 870 women was 13-trisomy-positive and was diagnosed by amniocentesis and fetal chromosome karyotype analysis, 22 of which was diagnosed as 47, XN, +13 and four of which was normal; the diagnosis accuracy of non-invasive prenatal testing (NIPT) was 84.6%. 18 out of the 22 confirmed cases underwent abortion, three cases had termination of embryonic development, and one case had postnatal anomaly. Thirty four out of the 2520 pregnant women was 18-trisomy-positive and was diagnosed by amniocentesis and fetal chromosome karyotype analysis, 31 of which was diagnosed as 47, XN, +18 and three cases were normal; the diagnosis accuracy of NIPT was 91.2%. 29 out of the 31 confirmed cases underwent abortion and two cases had termination of embryonic development. Forty out of the 2520 pregnant women was 21-trisomy-positive and was diagnosed by amniocentesis and fetal chromosome karyotype analysis, 39 of which was diagnosed as 47, XN, +21 and one case was normal; the diagnosis accuracy of NIPT was 97.5%. Thirty four out of the 39 confirmed cases underwent abortion, three cases had termination of embryonic development, and two cases had postnatal anomaly. Twenty eight cases were tested as sex chromosome-positive and were diagnosed by amniocentesis and fetal chromosome karyotype analysis, 25 out of which was diagnosed as abnormal and three cases were normal; the diagnosis accuracy of NIPT was 89.3%. 24 out of the 25 confirmed cases underwent abortion, and one case had termination of embryonic development. Conclusion: Prenatal screening and non-invasive gene sequencing technology have a high accuracy in the diagnosis of fetal birth defects, which can reduce the maternal abortion injury as much as possible and relieve the psychological pressure. The promotion of the mode can be strengthened in clinics. doi: https://doi.org/10.12669/pjms.36.7.2290 How to cite this:Bu J, Jiang P, Cui X, Zhou H, Han F. Application values of prenatal screening and non‑invasive gene sequencing in fetal birth defects. Pak J Med Sci. 2020;36(7):---------. doi: https://doi.org/10.12669/pjms.36.7.2290 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.