[ Ana Sayfa | Editörler | Danışma Kurulu | Dergi Hakkında | İçindekiler | Arşiv | Yayın Arama | Yazarlara Bilgi | E-Posta ]
Fırat Tıp Dergisi
2008, Cilt 13, Sayı 1, Sayfa(lar) 077-079
[ Özet ] [ PDF ] [ Benzer Makaleler ] [ Yazara E-Posta ] [ Editöre E-Posta ]
A Case With 46,X, +mar (Y), inv (Y) (p11.2;q11.23)? Karyotype
Ülkü ÖZBEY, Hüseyin YÜCE
Fırat Üniversitesi, Tıp Fakültesi Tıbbi Biyoloji Anabilim Dalı, ELAZIĞ
Keywords: Prenatal diagnosis, SRY, marker Y chromosome, FISH, inversion, Prenatal tanı, SRY, marker Y kromozom, FISH, inversiyon
Summary
Pericentric inversion of Y chromosome has an estimated frequency of the one per thousand. This inversion is always inherited but also is possible a de novo presentation. Sometimes this inverted chromosome is associated with the Down, Klinefelter and other chromosomal syndromes. For the carriers of pericentric inversion the risk of the mental retardation or multiple abortion is not apparently increase and there is not relation with abnormal phenotypic features. The pericentric inversion of Y chromosome is only a rare chromosomal heteromorphism. Chromosome analysis of the father is advisable to determine whether or not the inversion is familial in order to be able to provide genetic counselling. Cytogenetic analysis from amniotic fluid cells and parents’ peripheral blood lymphocyte cultures were prepared by routine methods. Fluorescence in situ hybridization (FISH) was performed on cultured amniotic fluid cells to confirm the presence of Y-bearing cells. We performed molecular genetic analysis for Y chromosomal loci (SRY, ZFY, SY84, SY86, SY127, SY134, SY254, SY255). In cytogenetic analysis, the karyotype of male fetus, other brother’s and his father’s were exhibited as 46,X, +mar (Y), inv (Y) (p11.2;q11.23)?. His mother’s was 46, XX. In these cases, it was concluded that there was no clinical significance because the same abnormality was found in other members of the family. All of them have normavl phenotypic features. This finding suggests that the pericentric inversion of the Y chromosome affects neither the phenotype nor reproductive performance. ©2008, Firat University, Medical Faculty.
  • Top
  • Summary
  • Introduction
  • Case Presentation
  • Disscussion
  • References
  • Introduction
    Pericentric inversion of the human Y chromosome has an estimated frequency of the one per thousand. This inversion is always inherited but also is possible a de novo presentation. Sometimes this inverted chromosome is associated with the Down, Klinefelter and other chromosomal syndromes. For the carriers of pericentric inversion the risk of the mental retardation or multiple abortion is not apparently increase and there is not relation with abnormal phenotypic features. For some authors the pericentric inversion of the human Y chromosome is only a rare chromosomal heteromorphism1,2.

    In this paper, we report a rare male case with no malformation and a 46,X,+mar (Y), inv(Y) (p11.2;q11.23)? karyotype, in whom the marker chromosome appears by molecular analysis to have been derived from the Y chromosome. The importance of banding studies for precise identification of structurally abnormal chromosomes and the need for chromosome study of family members for the peroper counseling of prenatal diagnosis of such a variant chromosome are discussed. In the presentation of this case, it has been aimed to resolve the socio-psychologic problems at the patients and his/her relatives and to be a guide to doctors about this subject.

  • Top
  • Summary
  • Introduction
  • Case Presentation
  • Disscussion
  • References
  • Case Presentation
    Cytogenetic analysis was performed with GTG-banding. Cytogenetic analysis analyses from amniotic fluid cells and parents’ peripheral blood lymphocyte cultures were prepared by routine methods. For each case at least 25 metaphases were evaluated. Structural anomalies were recorded according to the International System for Human Cytogenetic Nomenclature. Fluorescence in situ hybridization (FISH) was performed on cultured amniotic fluid cells to confirm the presence of a Ybearing cell line and determine its distribution in the fetal tissue examined. The cases were analysed by also interphase FISH technique using dual prob (Vysis, Ullinois, USA) to exhibit exist Y chromosome. Hybridization was performed in according to the manufacturer’s instructions. Dual-labeling hybridization was performed using 10Vl of the hybridization mixture containing fluorescein direct labeled chromosome Y alpha-satellite probe and rhodamine direct-labelled SRY gene probe. Molecular analysis of sex-reversed patients led to the discovery of the SRY gene (sex-determining region on Y). We performed molecular genetic analysis for Y chromosomal loci (SRY, ZFY, SY84, SY86, SY127, SY134, SY254, SY255) blood leukocytes with Y Chromosoma Deletion Kit (Dr.Zeydanlı Life Science, Ankara, Turkey).

    Genomic DNA was extracted from peripheral leukocytes collected from a venous blood sample. Genomic DNA was extracted by standard methods from peripheral leukocytes of all patients3. The DNA was amplified for 30 cycles with denaturation at 94ºC for 5 min, at 94ºC for 1 min, at 54ºC 1 min, at 72ºC for 2 min and extension at 72ºC for 6 min using a PTC-100 thermal cycler (MJ Research). The PCR products were separated by electrophoresis on 2 per cent agarose gel containing ethidium bromide and photographed using Gel Doc system (Hero Lab, Germany). Product was obtained 947 bp for Y. Health male and female samples were used as positive and negative control.

    A pericentric inversion of chromosome Y was detected in an unborn baby by a second-trimester amniocentesis for prenatal diagnosis because of advanced maternal age. Cytogenetic investigations of the fetal cells revealed a male karyotype with a pericentric inversion of the Y chromosome. Cytogenetic analysis from amniotic fluid cells showed 46,X,+mar (Y) inverted Y (p11.2;q11.23)? (Figure 1). Chromosome analysis of the proband’s father and other elder brother was also undertaken in order to decide whether this inversion was inherited or of de novo origin. The identical pericentric inversion was found in the phenotypically normal proband's father and a elder brother. In this case of familial pericentric inversion, the parents were assured that their unborn baby was anticipated to be normal.


    Click Here to Zoom
    Figure 1: Pericentric inversion of the Y chromosome in this family. Left, diagram showing a normal Y (Y) from a healthy individual and the common inv(Y)(p11.2;q11.23) chromosome [inv(Y)] of the male family members. Right, high resolution G banding of a normal Y (N) and the Y chromosome of case (P).

    The existence of Y chromosome was determined by interphase FISH besides a number of metaphase analysis. It was detected SRY gene and centromeric signals in patients with 46,X,+mar(Y), inverted Y(p11.2; q11.23) karyotype (Figure 2). The formation of testes can be considered as existence of SRY (sex-determining region of Y) as a testisdetermining factor. The sequence tagged sites (STS) primers SY14, ZFY, sY84, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc) were used for each case. In all cases the SRY gene was present. No mutations were identified in this gene in any of the patients (Figure 3).


    Click Here to Zoom
    Figure 2: The existence of SRY gene was determined by interphase FISH.


    Click Here to Zoom
    Figure 3: Gel photograph showing Y microdeletion. Lane 1, molecular weight marker; lane 2 and 3 negative control (female and male samples), lane 4,5,6,7,8,9,10 and 11: SY14, sY84, ZFY, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc).

    The amplified loci by PCR in each patient are indicated in the Table 1. The present report illustrates the importance of FISH and molecular techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.


    Click Here to Zoom
    Table 1: Amplified loci by PCR in two patients with 46,X,inv(Y)

  • Top
  • Summary
  • Introduction
  • Case Presentation
  • Disscussion
  • References
  • Discussion
    We are reporting three subjects with apparently the same chromosomal constitutions (46,X,mar(Y)) as demonstrated by cytogenetic and molecular analyses performed in peripheral blood lymphocytes and amniotic fluid cells. All patients had the same Y-chromosome specific sequences. FISH hybridization signals on marker chromosomes confirmed that they are derived from Y-chromosome in all patients. Furthermore, PCR analysis with Y-chromosome specific sequences allow us to conclude definitively that these marker chromosomes were Y-derived.

    Prenatal diagnosis has become the major focus of genetic counselling and for this, several important areas of technology have evolved. Especially cytogenetic prenatal diagnosis using analysis of cultured cells from the amniotic fluid at midtrimester was introduced in 1966 by Steele and Breg4. Most cases with structural aberrations of sex chromosomes are associated with abnormalities of the external genitalia at birth or lack of secondary sexual characteristics at puberty5. The molecular study of individuals with abnormal gonadal differentiation and sex chromosome anomalies has led to the assignment of specific regions for sexual differentiation and gonadal function on the Y chromosome6-8. Recently, investigation with DNA probes has allowed the generation of a physical deletion map dividing the Y chromosome into eight intervals9, and more detailed deletion mapping has been reported10. Many individuals with sex chromosome abnormalities remain undiagnosed because usually their phenotype falls within the limits of ‘normality,’ although the karyotypic change has an effect on most non-mosaic cases. Even now, when many abnormalities of the sex chromosomes have been defined and their clinical consequences reported in detail, the precise role of the sex chromosomes in sex differentiation and in the genetic control of gametogenesis still remain obscure. FISH is a rapid method for the detection of specific DNA target sequen ces in metaphase and interphase chromosomes. These techniques, combined with conventional G-banding, have a clear diagnostic and prognostic value, and contribute to genetic counselling11.

    In 1999, Acar et al were reported conventional and molecular cytogenetic studies in a patient with multiple anomalies who is a carrier of a pericentric inversion on chromosome Y and a chromosome 15p+. His parents were phenotypically normal. The father is a carrier of a pericentric inversion of chromosome Y, and the mother carries a large chromosome 15p+ variant12.

    In our study, the inverted Y was found to be of paternal origin. Maternal chromosomal pattern was normal 46,XX. Cytogenetic investigation of a healthy couple with 2 spontaneous abortions revealed a pericentric inversion of the Y chromosome. In these cases, it was concluded that there was no clinical significance because the same abnormality was found in two other members of the family. All of them have not anormal phenotype. Chromosome analysis of the father is advisable to determine whether or not the inversion is familial in order to be able to provide genetic counselling. This finding suggests that the pericentric inversion of the Y chromosome affects neither the phenotype nor reproductive performance. After reviewing the literature, it was concluded that an inverted Y chromosome does not impede the production of normal sperm and does not predispose to non-disjunction of other chromosomes in the progeny. Thus, the earlier concept of nondisjunction was rejected, and it is suggested that aberrant cases with aneuploidy and an inverted Y are fortuitous. The prevalence of males with pericentric Y inversion in the general population is approximately 1 per 1000. It is suggested that a pericentric inversion of the Y chromosome is a rare chromosomal heteromorphism and should be called type III. The pericentric inverted Y is inherited from generation to generation and has no clinical significance.

  • Top
  • Summary
  • Introduction
  • Case Presentation
  • Discussion
  • References
  • References

    1) Motos Guirao MA. Pericentric inversion of the human Y chromosome. An Esp Pediatr. 1989; 31: 583-587.

    2) Shapiro LR, Pettersen RO, Wilmot PL, Warburton D, Benn PA, Hsu LY. Pericentric inversion of the Y chromosome and prenatal diagnosis. Prenat Diagn.1984; 4: 463-465.

    3) Sambrook J, Fritsch EF, Maniatis T. Molecular cloning: A laboratory manual. Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 1989.

    4) Park SY, Kim JW, Kim YM, Kim JM, Lee MH, Lee BY, Han JY, Kim MY, Yang JH, Ryu HM. Frequencies of fetal chromosomal abnormalities at prenatal diagnosis: 10 years experiences in a single institution. J Korean Med Sci. 2001; 16: 290-293.

    5) Davis RM. Localization of male determining factors in man: a thorough review of structural anomalies of the Y chromosome. J. Med. Genet.1981; 18: 161-195.

    6) Page, DC. Sex reversal: deletion mapping the male-determining function of the human Y chromosome, Cold Spring Harbor Symp. Quant. Biol. 1986; 51: 229-235.

    7) Page DC, Mosher R, Simpson E.M, Fisher EMC, Mardon G, Pollack J, McGillivray B, de la Chapelle A, Brown LG. The sexdetermining region of the human Y chromosome encodes a finger protein. Cell.1987; 51: 1091-1104.

    8) Simpson E, Chandler P, McLaren A, Goulmy E, Disteche C.M, Page, D.C, Ferguson-Smith, M.A. Mapping the H-Y gene. Development.1987; 101(Suppl.): 157-161.

    9) Vergnaud G, Page DC, Simmler M-C, Brown L, Rouyer F, Noel B, Botstein D, de la Chapelle A, Simpson JL. A deletion map of the human Y chromosome based DNA hybridization. Am. J. Hum. Genet. 1986; 38: 109-124.

    10) Vollrath D, Foote S, Hilton A, Brown LG, Beer-Romero P, Bogan JS, Page DC. The human Y chromosome: a 43-interval map based on naturally occurring deletions, Science.1992; 258: 52-59.

    11) Hernando C, Carrera M, Ribas I, Parear N, Baraibar R, Egocue J, Fuster C. Prenatal and postnatal characterization of Y chromosome structural anomalies by molecular cytogenetic analysis.Prenat Diagn. 2002; 22: 802-805.

    12) Acar H, Cora T, Erkul I. Coexistence of inverted Y, chromosome 15p+ and abnormal phenotype.Genet Couns. 1999; 10: 163-70.

  • Top
  • Summary
  • Introduction
  • Case Presentation
  • Discussion
  • References
  • [ Başa Dön ] [ Özet ] [ PDF ] [ Benzer Makaleler ] [ Yazara E-Posta ] [ Editöre E-Posta ]
    [ Ana Sayfa | Editörler | Danışma Kurulu | Dergi Hakkında | İçindekiler | Arşiv | Yayın Arama | Yazarlara Bilgi | E-Posta ]