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LETTER TO EDITOR  
Year : 2011  |  Volume : 54  |  Issue : 3  |  Page : 655-657
Mixed gonadal dysgenesis with 45,X/46,X,idic(Y) karyotype: A case report


Transplant Immunology, Molecular Biology and Transfusion Medicine, Apollo Hospitals, Sarita Vihar, Delhi Mathura Road, New Delhi, India

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Date of Web Publication20-Sep-2011
 

How to cite this article:
Srivastava P, Makroo R N, Chowdhry M, Mishra M, Fauzdar A. Mixed gonadal dysgenesis with 45,X/46,X,idic(Y) karyotype: A case report. Indian J Pathol Microbiol 2011;54:655-7

How to cite this URL:
Srivastava P, Makroo R N, Chowdhry M, Mishra M, Fauzdar A. Mixed gonadal dysgenesis with 45,X/46,X,idic(Y) karyotype: A case report. Indian J Pathol Microbiol [serial online] 2011 [cited 2019 Dec 9];54:655-7. Available from: http://www.ijpmonline.org/text.asp?2011/54/3/655/85141


Sir,

This is in reference to the article on mixed gonadal dysgenesis with normal karyotype: A rare case report published in 2010. [1] Here, we present a mosaic 45,X/46,X,idic(Y) boy with a slightly ambiguous male genitalia, whose abnormal Ycontaining marker chromosome was delineated as an idic(Y)(p11.3) on peripheral blood karyotyping, which was further confirmed on fluorescence in situ hybridization (FISH). Mosaic sex chromosome disorder is a difficult issue in genetic counselling. We thus find our case interesting and clinically relevant because of the extensive laboratory workup.

Mixed gonadal dysgenesis (MGD) comprises a heterogeneous group of diverse chromosomal, gonadal, and phenotypic abnormalities, which are characterized by the presence of a testis on one side and a contra-lateral streak or an absent gonad. [2] One of the most common abnormal Y chromosome is a dicentric fragment present as part of a mosaic karyotype, which includes a 45,X cell line.[3] The phenotype ranges from female to male, depending on the presence or absence of the testis-determining gene SRY and, on the degree of mosaicism and the tissue distribution of the 45,X cell line. [4] As dicentric chromosomes are inherently unstable, a mosaic monosomic X (45,X) cell line is frequently present. Mosaicism for 45,X/46,XY exhibits wide variability ranging from Turner syndrome to mixed gonadal dysgenesis to normal males with 45,X/46,XY mosaicism. [2]

The patient is a 30-year-old male referred to our hospital for evaluation of ambiguous external genitalia. He is the first child in a sib ship of two of a non-consanguineous marriage with uneventful birth history. The family reports his development delay and was shorter than his peers. His physical examination was normal. The external genitalia comprised of proximal penile hypospadia. Dorsal hood and chordee were present. No gonadal structures were palpable. Pelvic ultrasonography did not detect any gonadal tissue. No prostrate was detected on ultrasonography. The patient underwent excision of right testis in 1989 and reported as ovo-testis. He underwent orchidopexy of the left testis followed by excision of the left testis in 1990. His follicle stimulating hormone (FSH) and luteinizing hormone levels were raised, whereas the levels of testosterone were decreased.

Cytogenetic analysis of the peripheral blood showed the presence of two cell lines. Of the 100 cells analyzed, the karyotype was 45,X(20)/46,X,idic(Y)(80) by conventional G-banding analysis [Figure 1] and [Figure 2]. FISH analysis for centromeric Y sequences (DYZ3; Vysis) and for Satellite III region Yp 12 of Chromosome Y Spectrum Green was performed and the chromosome was found to be isodicentric [Figure 3] and [Figure 4].
Figure 1: Modal karyotype: 46,X,Idic(Y)(p11.3)

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Figure 2: Modal karyotype: 45,X

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Figure 3: FISH Probe for Centromeric Y Sequences for region Yp 11.1 - q11.1 (DYZ3) Alpha Satellite Spectrum Orange was successfully hybridized and two spectrum orange signals are seen signifying
dicentricity


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Figure 4: FISH Probe for Satellite III region Yp 12 of Chromosome Y Spectrum Green was successfully hybridized and two spectrum green signals are seen signifying isodicentricity

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In most cases of 45,X/46,XY mosaicism, the cause is considered to be the loss by nondsjunction of the Y chromosome after normal disomic fertilization. In the monozygotic patients described in previous reports, they have distinct sexual phenotypes due to different ratios of mosaicism. Previous reports on Y-containing derivative chromosomes in mosaic 45,X cases revealed that the derivative Y chromosomes could be idic(Yp), idic (Yq), or Y microdeletions. [4] Such rearrangements are generally unstable and an additional 45,X cell line is frequently present. [5] In the present case, the peripheral blood lymphocytes showed 80% of cells with an idicY chromosome. As gonadal tissues are not easily available, there are few reports on such comparisons [6] , and most studies correlate phenotype with peripheral lymphocyte karyotypes, which was also the case in our study.

FISH-based technology is more useful in studying mosaic genotypes. [1] We successfully used FISH for the present study, which complemented well with the peripheral blood karyotyping.

Formation of the testis from the undifferentiated embryonic gonad depends on the presence of the short arm of the Y chromosome, containing SRY-sequences. There seems to be the necessity of a minimal amount of SRY to be present for the undifferentiated gonad to become a testis. Apparently, in our case, the threshold of SRY-containing cells required for the development of the embryonic gonad into a testis was obviously adequate to enable complete differentiation of the left gonad into a testis, although infertility may be a distinct possibility.

 
   References Top

1.Anand A, Gupta NP, Singh MK, Mathur SR, Nayyar R. Mixed gonadal dysgenesis with normal karyotype: A rare case report. Indian J Pathol Microbiol 2010;53:313-5.  Back to cited text no. 1
[PUBMED]  Medknow Journal  
2.Caglayan AO, Demiryilmaz F, Kendirci M, Ozyazgan I. Mixed gonadal dysgenesis with 45,X/46,X,idic(Y)/46,XY,idic(Y) karyotype. Genet Couns 2009;20:173-9.  Back to cited text no. 2
    
3.Robinson DO, Dalton P, Jacobs PA, Mosse K. A molecular and FISH analysis of structurally abnormal Y chromosomes in patients with Turner syndrome. J Med Genet 1999;36:279-84.  Back to cited text no. 3
    
4.Fernandez R, Pasaro E. Molecular analysis of an idic(Y)(qter®p11.32: p11.32®qter) chromosome from a female patient with a complex karyotype. Genet Mol Res 2006;5:399-406.  Back to cited text no. 4
    
5.Hsu LY. Phenotype/karyotype correlations of Y chromosome aneuploidy with emphasis on structural aberrations in postnatally diagnosed cases. Am J Med Genet 1994;53:108-10.  Back to cited text no. 5
    
6.Quilter CR, Nathwani N, Conway GS, Stanhope R, Ralph D, Bahadur G, et al. A comparative study between infertile males and patients with Turner syndrome to determine the influence of sex chromosome mosaicism and the breakpoints of structurally abnormal Y chromosome on phenotyping sex. J Med Genet 2002;39:80-4.  Back to cited text no. 6
    

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Correspondence Address:
Mohit Chowdhry
Transplant Immunology, Molecular Biology and Transfusion Medicine, Apollo Hospitals, Sarita Vihar, Delhi Mathura Road, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.85141

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