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Title: Somatic mosaicism and female-to-female transmission in a kindred with hemophilia B (factor IX deficiency)

Abstract

Studies have shown that hemophilia B (Christmas disease; factor IX deficiency) results from many different mutations in the factor IX gene, of which {gt}95% are single nulceotide substitutions. This study has identified a previously unreported form of hemophilia B in a patient who was a somatic mosaic for a guanine-to-cytosine transversion at nucleotide 31,170 in the factor IX gene. This point mutation changes the codon for residue 350 in the catalytic domain of factor IX from a cysteine to a serine. The authors used differential termination of primer extension to confirm and measure the degree of mosaicism. The study shows that a varying proportion of cells from hepatic, renal, smooth muscle, and hematopoietic populations possessed normal as well as mutant factor IX sequences. These results indicate that the mutation in this patient occurred either as an uncorrected half-chromatid mutation in the female gamete or as a replication or postreplication error in the initial mitotic divisions of the zygote preceding implantation. In addition, this kindred also contains two females in successive generations who have moderately severe factor IX deficiency. The molecular pathogenesis of this latter phenomenon has been studied and seems to relate to the unaccompanied expression of the mutant factormore » IX gene consequent upon a second, as yet undefined, genetic event that has prevented inactivation of sequences including the mutant factor IX gene on the X chromosome inherited from the affected male.« less

Authors:
; ;  [1]
  1. (Queen's Univ., Kingston, Ontario (Canada))
Publication Date:
OSTI Identifier:
5079758
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States); Journal Volume: 88:1
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; DNA; AUTORADIOGRAPHY; GENE MUTATIONS; DNA SEQUENCING; HEMOPHILIA; MOLECULAR BIOLOGY; DNA BASE TRANSITIONS; HEREDITARY DISEASES; PATIENTS; DISEASES; HEMIC DISEASES; MUTATIONS; NUCLEIC ACIDS; ORGANIC COMPOUNDS; STRUCTURAL CHEMICAL ANALYSIS; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Taylor, S.A.M., Deugau, K.V., and Lillicrap, D.P. Somatic mosaicism and female-to-female transmission in a kindred with hemophilia B (factor IX deficiency). United States: N. p., 1991. Web. doi:10.1073/pnas.88.1.39.
Taylor, S.A.M., Deugau, K.V., & Lillicrap, D.P. Somatic mosaicism and female-to-female transmission in a kindred with hemophilia B (factor IX deficiency). United States. doi:10.1073/pnas.88.1.39.
Taylor, S.A.M., Deugau, K.V., and Lillicrap, D.P. 1991. "Somatic mosaicism and female-to-female transmission in a kindred with hemophilia B (factor IX deficiency)". United States. doi:10.1073/pnas.88.1.39.
@article{osti_5079758,
title = {Somatic mosaicism and female-to-female transmission in a kindred with hemophilia B (factor IX deficiency)},
author = {Taylor, S.A.M. and Deugau, K.V. and Lillicrap, D.P.},
abstractNote = {Studies have shown that hemophilia B (Christmas disease; factor IX deficiency) results from many different mutations in the factor IX gene, of which {gt}95% are single nulceotide substitutions. This study has identified a previously unreported form of hemophilia B in a patient who was a somatic mosaic for a guanine-to-cytosine transversion at nucleotide 31,170 in the factor IX gene. This point mutation changes the codon for residue 350 in the catalytic domain of factor IX from a cysteine to a serine. The authors used differential termination of primer extension to confirm and measure the degree of mosaicism. The study shows that a varying proportion of cells from hepatic, renal, smooth muscle, and hematopoietic populations possessed normal as well as mutant factor IX sequences. These results indicate that the mutation in this patient occurred either as an uncorrected half-chromatid mutation in the female gamete or as a replication or postreplication error in the initial mitotic divisions of the zygote preceding implantation. In addition, this kindred also contains two females in successive generations who have moderately severe factor IX deficiency. The molecular pathogenesis of this latter phenomenon has been studied and seems to relate to the unaccompanied expression of the mutant factor IX gene consequent upon a second, as yet undefined, genetic event that has prevented inactivation of sequences including the mutant factor IX gene on the X chromosome inherited from the affected male.},
doi = {10.1073/pnas.88.1.39},
journal = {Proceedings of the National Academy of Sciences of the United States of America; (United States)},
number = ,
volume = 88:1,
place = {United States},
year = 1991,
month = 1
}
  • Previous molecular estimates of mosaicism in the dystrophin and other genes generally have focused on the transmission of the mutated allele to two or more children by an individual without the mutation in leukocyte DNA. We have analyzed 414 families with hemophilia B by direct genomic sequencing and haplotype analysis, and have deduced the origin of mutation in 56 families. There was no origin individual who transmitted a mutant allele to more than one child. However, somatic mosaicism was detected by sequence analysis of four origin individuals (3{female} and 1{male}). The sensitivity of this analysis is typically one part inmore » ten. In one additional female who had close to a 50:50 ratio of mutant to normal alleles, three of four noncarrier daughters inherited the haplotype associated with the mutant allele. This highlights a caveat in molecular analysis: a presumptive carrier in a family with sporadic disease does not necessarily have a 50% probability of transmitting the mutant allele to her offspring. After eliminating those families in which mosaicism could not be detected because of a total gene deletion or absence of DNA from a deduced origin individual, 5 of 43 origin individuals exhibited somatic mosaicism at a level that reflects a mutation within the first few cell divisions after fertilization. In one patient, analysis of cervical scrapings and buccal mucosa confirm the generalized distribution of somatic mutation. Are the first few cell divisions post-fertilization highly mutagenic, or do mutations at later divisions also give rise to somatic mosaicism? To address this question, DNA from origin individuals are being analyzed to detect somatic mosaicism at a sensitivity of 1:1000. Single nucleotide primer extension (SNuPE) has been utilized in eight families to date and no mosaicism has been detected. When the remaining 30 samples are analyzed, it will be possible to compare the frequency of somatic mosaicism at 0.1-10% with that of {ge}10%.« less
  • In aiming to develop a gene therapy approach for hemophilia B, the authors expressed and characterized human factor IX in rat capillary endothelial cells (CECs). Moloney murine leukemia virus-derived retrovirus vectors that contain human factor IX cDNA linked to heterologous promoters and the neomycin-resistant gene were constructed and employed to prepare recombinant retroviruses. Rat CECs and NIH 3T3 cells infected with these viruses were selected with the neomycin analogue, G418 sulfate, and tested for expression of factor IX. A construct with the factor IX cDNA under direct control by long terminal repeat gave the highest level of expression as quantitatedmore » by immunoassays as well as clotting activity assays. A single RNA transcript of 4.4 kilobases predicted by the construct and a recombinant factor IX were found. The recombinant human factor IX produced showed full clotting activity, demonstrating that CECs have an efficient mechanism for posttranslational modifications, including {gamma}-carboxylation, essential for its biological activity. These results, in addition to other properties of the endothelium, including large number of cells, accessibility, and direct contact with the circulating blood, suggest that CECs can serve as an efficient drug delivery vehicle producing factor IX in a somatic gene therapy for hemophilia B.« less
  • The authors report studies of a female with severe hemophilia A resulting from a complex de novo translocation of chromosomes X and 17 (46,X,t(X; 17)). Somatic cell hybrids containing the normal X, the der(X), or the der(17) were analyzed for coagulation factor VIII (F8C) sequences using Southern blots and polymerase chain reaction. The normal X, always late replicating, contains a normal F8C gene, whereas the der(X) has no F8C sequences. The der(17) chromosome containing Xq24-Xq28 carries a functional G6PD locus and a deleted F8C allele that lacks exons 1--15. Also, it lacks the DXYS64-X locus, situated between the F8C locusmore » and the Xq telomere. These results indicate that a cryptic breakpoint within Xq28 deleted the 5[prime] end of F8C, but left the more proximal G6PD locus intact on the der(17)chromosome. As the deleted segment includes the 5[prime] half of F8C as well as the subtelomeric DXYS64 locus, F8C must be oriented on the chromosome with its 5[prime] region closest to the telomere. Therefore, the order of these loci is Xcen-G6PD-3[prime]F8C-5[prime]F8C-DXYS64-Xqtel. The analysis of somatic cell hybrids has elucidated the true nature of the F8C mutation in the pro-band, revealing a more complex rearrangement (three chromosomes involved) than that expected from cytogenetic analysis, chromosome painting, and Southern blots. A 900-kb segment within Xq28 has been translocated to another autosome. Hemophilia A in this heterozygous female is due to the decapitation of the F8C gene on the der(17) and inactivation of the intact allele on the normal X. 27 refs., 5 figs., 1 tab.« less
  • Familial idiopathic gonadotropin deficiency (FIGD) is an autosomal recessive disorder which results in failure to develop secondary sexual characteristics. The origin is a hypothalamic defect resulting in insufficient secretion of gonadotropin-releasing hormone GnRH (also called LHRH, luteinizing hormone releasing hormone) and follicle-stimuating hormone (FSH). FIGD has been determined to be a separate entity from Kallmann syndrome which presents with hypogonadism as well as anosmia. The FIGD phenotype appears to be analogous to the phenotype of the hpg (hypogonadal) mouse. Because the hpg phenotype is the result of a structurally abnormal GnRH gene, we have studied the GnRH gene in individualsmore » from a previously reported Brazilian FIGD family. An informative dimorphic marker in the signal peptide sequence of the GnRH gene allowed assessment of linkage between the disease gene and the GnRH locus in this pedigree. We have concluded that the GnRH locus is not linked to the disease-causing mutation in these hypogonadal individuals. Recent evidence suggests that neuropeptide Y (NPY) may play a role in the initiation of puberty. We hypothesize that mutations in NPY may result in failure to secrete GnRH. We have characterized three diallelic frequent-cutter restriction fragment length polymorphisms within the human NPY locus, and are currently using these markers to determine if the NPY gene is linked to, and possibly the site of the disease mutation in this kindred.« less