OBJECTIVETo study the human dystrophin gene molecular deletion mechanism, we analyzed breakpoint regions within junction fragments of deletion-type patients and investigated whether the dystrophin gene's intron structure might be related to intron instability.

METHODSJunction fragments corresponding to exon 46 and 51 deletions were cloned. The breakpoint regions were sequenced, and the features of introns with available Genebank sequences were analyzed.

RESULTSAn analysis of junction fragment sequences corresponding to exon 46 and 51 deletions showed that all 5' and 3' breakpoints are located within repeat sequences. No small insertions, small deletions, or point mutations are located near the breakpoint junctions. By analyzing the secondary structure of the junction fragments, we demonstrated that all junction fragment breakpoints are located in non-matching regions of single-stranded hairpin loops. A high concentration of repetitive elements is found to be a key feature of many dystrophin introns. In total, 34.8% of the overall dystrophin intron sequences is composed of repeat sequences.

CONCLUSIONRepeat elements in many dystrophin gene introns are the key to their structural bases and reflect intron instability. As a result of the primary DNA sequences, single-stranded hairpin loops form, increasing the instability of the gene, and forming the base for breaks in the DNA. The formation of the single-stranded hairpins can result in reattachment of two different breakpoints, producing a deletion.

Dystrophin ; genetics ; Humans ; Introns ; genetics ; Sequence Deletion

OBJECTIVE: To detect gene inversion in two pedigrees affected with Hemophilia A by using Nanopore sequencing technology. METHODS: Peripheral blood samples were taken from members of the two pedigrees. Following extraction of genome DNA, genetic variants of the carriers were detected by Nanopore sequencing and subjected to bioinformatic analysis. RESULTS: Nanopore sequencing has identified the niece of the proband of the pedigree 1 as carrier of Hemophilia A Inv22, and the mother of the proband of the pedigree 2 as carrier of Hemophilia A Inv1, which was consistent with clinical findings. Breakpoint sites in both pedigrees were accurately mapped. Statistical analysis of the sequencing results revealed a large number of variations in the carriers' genomes including deletions, duplications, insertions, inversions and translocations. CONCLUSION Nanopore sequencing can be used to analyze gene inversions associated with Hemophilia A, which also provided a powerful tool for the diagnosis of diseases caused by gene inversions.
Chromosome Inversion/genetics* ; Hemophilia A/genetics* ; Humans ; Introns ; Nanopore Sequencing ; Pedigree

Group Ⅱ introns are self-splicing ribozymes, which insert directly into target sites in DNA with high frequency through "retrohoming". They specifically and efficiently recognize and splice DNA target sites, endowing themselves with great potential in genetic engineering. This paper reviewed the gene targeting principle of group Ⅱ introns and the application in microbial genetic modification, and then analyzed the limitations of them in multi-functional gene editing and eukaryotes based on the "retrohoming" characteristics and the dependence on high Mg²⁺ concentration. Finally, we dissected the potential of group Ⅱ introns in the development of novel gene editing tools based on our previous research outcome and the structural characteristics of the introns, hoping to provide a reference for the application of group Ⅱ introns in biotechnology.
DNA ; Eukaryota ; Gene Targeting ; Introns/genetics* ; RNA, Catalytic/genetics*

Estrogen receptor (esr) mediates the effects of estrogen on the expression of related genes, thereby regulating the growth and reproduction of mammals. To investigate the effect of retrotransposon insertion polymorphism (RIP) of the porcine esr gene on porcine growth performance, retrotransposon insertion polymorphism of the esr gene were predicted by comparative genomics and bioinformatics, and PCR was used to verify the insertion polymorphisms in different porcine breeds. Finally, the correlation analysis between the genotypes and performance of Large White pigs was conducted. The results showed that four retrotransposon polymorphic sites were identified in the esr1 and esr2 genes, which are esr1-SINE- RIP1 located in intron 2 of the esr1 gene, esr1-LINE-RIP2 and RIP3-esr1- SINE located in intron 5 of the gene, and esr2-LINE-RIP located in intron 1 of the esr2 gene, respectively. Among them, insertion of a 287 bp of SINE into intron 2 of the esr1 gene significantly affected (P<0.05) the live back fat thickness and 100 kg body weight back fat thickness of Large White pigs. Moreover, the live back fat thickness and back fat thickness at 100 kg body weight of homozygous with insertion (SINE+/+) was significantly greater than that of heterozygous with insertion (SINE+/-) and homozygous without insertion (SINE-/-). Therefore, esr1-SINE-RIP1 could be used as a molecular marker to assist the selection of deposition traits in Large White pigs.
Animals ; Genotype ; Introns/genetics* ; Phenotype ; Polymorphism, Genetic/genetics* ; Retroelements/genetics* ; Swine/genetics*

OBJECTIVE: To report on a case with severe hemophilia A (HA) due to a large duplication of F8 gene. METHODS: Inversion detection, Sanger sequencing, and multiplex ligation-dependent probe amplification (MLPA) were used to detect the mutation in the proband and his mother. RESULTS: The patient, a 7-year-old boy, was diagnosed with severe HA at 8 months. No inhibitor was developed over 150 exposure days. Intronic inversion detection and Sanger sequencing have failed to identify pathogenic variants, while MLPA revealed a large duplication [Ex 1_22 dup (2 copies)] in the proband, for which his mother was a carrier [Ex 1_22 dup (3 copies)]. Large duplications of the F8 gene have so far been found in 24 HA patients, all of whom had a severe phenotype, only one had a history of inhibitors. CONCLUSION Large duplications of F8 gene are associated with severe HA. The diagnostic rate for HA may be increased by MLPA.
Child ; Factor VIII/genetics* ; Gene Duplication ; Hemophilia A/genetics* ; Humans ; Introns ; Male ; Mutation ; Phenotype

OBJECTIVE: To explore the molecular mechanism of a case where RhD genotyping did not match serological results. METHODS: The serological results of 8 members from two generations of this family were analyzed. And according to Mendelian law of inheritance, RhD genotyping, zygotic type determination and gene sequencing were performed for the family members. RESULTS: The proband and one of her cousins have the same RhD alleles, both of them have a 336-1G>A intron variant RhD allele and a complete RhD deletion allele. The variant alleles are inherited from two of their parents with blood relationship, while the complete-deleted alleles come from the other. 336-1G>A means that the last base G of the second intron of the RhD gene is mutated to A, which leads to a negative RhD serology and a positive genotype in the proband. CONCLUSION There was a rare 336-1G> A intron variant gene (RhD * 01N.25) in this family, which was a recessive gene relative to the RhD gene and resulted in RhD phenotype negative.
Alleles ; Female ; Genotype ; Humans ; Introns/genetics* ; Pedigree ; Phenotype ; Rh-Hr Blood-Group System/genetics*

OBJECTIVE: To investigate the relationship between the type of FⅧgene mutation and the development of FⅧ inhibitors in patients with severe haemophilia A (HA). METHODS: The medical records of 172 patients with severe hemophilia A from January 2009 to September 2020 were reviewed. The types of FⅧgene mutations and the production of factor Ⅷ inhibitors were collected and divided into high-risk mutation group ( intron 1 inversions, large deletions, nonsense mutations), low-risk mutation group (missense mutations, small deletions and insertions, splice site mutations) and intron 22 inversions group. The correlation of FⅧgenotype and the production of FⅧ inhibitors in patients with HA were analyzed. RESULTS: Among 172 patients with severe HA, 21 cases(12.21%) developed FⅧ inhibitors. The cumulative incidence of FⅧ inhibitor development was 32%(10/31) in high risk group (75% patients with large deletions, 43% patients with intron 1 inversions, 20% patients with nonsense mutations) and 5%(2/43) in low risk group(6% patients with missense mutations, 5% patients with small deletions or insertions and 0% patient with a splice site mutation) and 9%(9/98) in intron 22 inversions group. Compared with the risk of FⅧ inhibitor development in intron 22 inversions group, the risk of FⅧ inhibitor development in high risk group was higher (OR＝4.7, 95% CI： 1.7-13.0), the risk of FⅧ inhibitor development in low risk group was equal (OR＝0.5, 95% CI： 0.1-2.3). Compared with the risk of inhibitor development in low risk group, the risk of FⅧ inhibitor development in high risk group was higher (OR＝9.8, 95% CI： 2.0-48.7). CONCLUSION Gene mutations of patients with severe HA in high-risk group which include intron 1 inversions, large deletions, nonsense mutations are a risk factor for FⅧ inhibitor production.
Codon, Nonsense ; DNA Mutational Analysis ; Factor VIII/genetics* ; Hemophilia A/genetics* ; Humans ; Introns ; Mutation

OBJECTIVE: To detect pathogenic variant in a child featuring Usher syndrome type II. METHODS: Peripheral blood samples of the child and his parents were collected for the analysis of variants of hearing impairment-related genes. The findings were verified in 100 individuals with normal hearing. RESULTS: The child was found to harbor compound heterozygous variants of the USH2A gene, namely c.8224-1G>C in intron 41 and c.5678C>G(p.Ser1893X) in exon 28, which were inherited respectively from his mother and father. Based on the American College of Medical Genetics and Genomics standards and guidelines, both c.8224-1G>C and c.5678C>G(p.Ser1893X) variants of USH2A gene were predicted to be pathogenic(PVS1+PM2+PM3). CONCLUSION The compound heterozygous variants c.8224-1G>C and c.5678C>G of the USH2A gene probably underlay the disease in this child. Above finding has enriched the spectrum of USH2A gene variants.
Child ; Exons ; Extracellular Matrix Proteins/genetics* ; Family ; Humans ; Introns ; United States ; Usher Syndromes/genetics*

OBJECTIVETo analyze intron 1 and 22 inversions in factor VIII (FVIII) gene in hemophilia A (HA) patients and and their families and to investigate the correlation between intron inversion and FVIII antibody.

METHODSAll patients were detected FVIII: C and FVIII antibody. In addition, 81 unrelated HA patients were directly detected by multiplex PCR and long-distance PCR for intron 1 and 22 inversions in FVIII gene. Pedigree investigation for some patients were conducted.

RESULTSIn 81 unrelated HA patients, 3 severe cases were found intron 1 inversion which accounted for 4.6% of total 65 severe cases. Of the 3 cases, one was FVIII antibody positive. Two female family members of a intron 1 inversion patient were identified as one carrier and one non-carrier. Twenty five of 65 (38.5%) severe cases were found intron 22 inversion. Of the 25 cases 1 was FVIII antibody positive. Nine female members in 5 HA families which had patients with intron 22 inversion were identified as 7 carries and 2 non-carriers.

CONCLUSIONBesides intron 22 inversion, intron 1 inversion was another important molecular defect in resulting in severe HA. Intron inversion analysis can also be used for deviation rectification of experiment grouping in HA patients. Intron 1 and 22 inversions may be one of the higher risk factors for resulting in FVIII antibodies.

Chromosome Inversion ; Chromosomes, Human, X ; Factor VIII ; genetics ; Female ; Hemophilia A ; genetics ; Humans ; Introns ; Male

OBJECTIVEInversions of intron 1 (Inv1) or intron 22 (Inv22) of the coagulation factor VIII gene (F8) may be found in 40%-50% of patients with severe hemophilia A. Such inversions cannot be detected by conventional sequencing. Due to homologous recombination, family-based linkage analysis may yield false positive or false negative results. In this study, Inverse-shifting PCR (IS-PCR) was used to detect potential inversions in two families affected with hemophilia A.

METHODSPeripheral venous blood, fetal amniotic fluid and fetal chorionic cells were harvested for genome DNA extraction. IS-PCR was used to detect Inv1 or Inv22 detection or its subtypes.

RESULTSIS-PCR has accurately detected Inv22 and Inv1 in both families and verified the subtypes of Inv22.

CONCLUSIONCarriers of Inv22 or Inv1 may be precisely detected with IS-PCR. The results have provided valuable information for genetic counseling and prenatal diagnosis for the affected families.

Child ; Chromosome Inversion ; Factor VIII ; genetics ; Genetic Counseling ; Hemophilia A ; diagnosis ; genetics ; Humans ; Introns ; Male ; Prenatal Diagnosis