Journal of Andrology, Vol. 28, No. 5, September/October 2007 Copyright E American Society of Andrology
Azoospermia Due to a Unique De Novo Balanced Reciprocal Translocation (Y;1) (q12;q25)
Case Report
MARKUS BRAUN-FALCO,* WERNER SCHEMPP,{ CLAUDIA NEVINNY-STICKEL-HINZPETER,{ ¨ HN§ AND FRANK-MICHAEL KO
Maraschio et al, 1994; Morel et al, 2002, Pabst et al, 2002; Pinho et al, 2005). We present a new variant of a balanced reciprocal (Y;1) translocation associated with azoospermia and we review the literature on this subject.
From the *Department of Dermatology; Institute of Human Genetics and Anthropology, University Medical Center Freiburg, Freiburg, Germany; `MVZ-Laboratory of Human Genetics, Munich, Germany; and §Andrologicum, Munich, Germany.
Case Report A 36-year-old man with azoospermia and a desire for children for 1.5 years was referred to the andrological outpatient department. The andrological history revealed surgery of the penis at age 3, and mumps infection without complicating autoimmune orchitis. Detailed information about the surgery was not available. Any infections or traumas in the genital area or undescended testicles were denied. The patient was a nonsmoker and nonalcoholic and was taking no regular medication. Physical examination of both testicles showed elastic consistency and a volume of approximately 15 ml; the deferent ducts, epididymides, and prostate were normal by palpation. There was a linear scar on the skin of the penis that did not influence erections. Testicular ultrasonography revealed a homogenous echo without signs of malignancy. Bilateral Doppler ultrasonography of the plexus pampiniformis did not demonstrate reflux during the Valsalva maneuver. A semen analysis after 5 days of sexual abstinence, performed twice within 2 months according to the World Health Organization guidelines (1999), demonstrated azoospermia with normal ejaculate volume (2.5 mL), pH 7.7, fructose level of 29.0 mmol/ ejaculate, and liquefaction time of 20 minutes. Although the levels of granulocyte elastase (1.038 ng/mL) and aglucosidase (22 mU/mL) in the seminal plasma were slightly abnormal, bacterial cultures excluded genital infection with pathologic bacteria, gonococci or mycoplasma. Seminal plasma IgA antibodies against Chlamydia trachomatis were not elevated. The levels of follicle-stimulating hormone (FSH) were within normal limits. A GTG-, CBG-banded cytogenetic analysis (Figure 1) was performed and demonstrated balanced (Y;1) translocation (ie, karyotype 46, X, t(Y;1) (q12;q25), without deletions in the azoospermic-factor AZF a, b or c regions), and DF508 mutation of the CFTR gene (CFTR intron 8 poly-T: 7T/9T) at one allele (heterozygous carrier of DF508). The reported t(Y;1)
A high prevalence of all types of chromosomal abnormalities has been found in male (4.29%) and female (5.88%) partners of infertile couples undergoing intracytoplasmic sperm injection (ICSI) (Morel et al, 2004). Aside from sex chromosome abnormalities (male, 1.82%; female, 4.44%), balanced reciprocal translocations are the most frequently found chromosomal abnormalities (male, 0.98%; female, 0.66%). In ICSI men, the probability of finding a balanced reciprocal translocation has been calculated to be 11.5-times higher than among newborns based on data on 7895 males referred for ICSI and 36 855 newborn males (Morel et al, 2004). Reciprocal translocation is defined as the exchange of chromosomal material between the arms of two heterologous chromosomes, thus changing the order, but usually not the amount of genetic material. Although all chromosomes can be involved in reciprocal translocations, chromosomes 12, 22, and Y are involved more often than expected on the basis of their relative lengths. A balanced reciprocal Y;autosome translocation has been demonstrated between almost every autosome, except chromosome 20 (Hsu, 1994), and even the participation of chromosome 1 seems to be relatively rare in infertile men. To our knowledge, only 10 cases of Y;1 translocation have been published previously (AlAwadi et al, 1985; Moreau et al, 1987; Narahara et al, 1987; Gregori-Romero et al, 1990; Teyssier et al, 1993; Correspondence to: Dr Markus Braun-Falco, Department of Dermatology, University of Freiburg, Hauptstraße 7, 79104 Freiburg, Germany (e-mail:
[email protected]). Received for publication November 10, 2006; accepted for publication March 22, 2007. DOI: 10.2164/jandrol.106.002030
647
648
Journal of Andrology
N
September October 2007
Figure 1. Cytogenetic analysis by GTG - and CBG-banding reveals the karyotype 46, XY, t(Y;1)(q12;q25).
(q12;q25) was further characterized by fluorescent in situ hybridization (FISH) using locus-specific probes DAZ (deleted in azoospermia), CDY (chromodomain Y), DYZ1 of Yq12, and the SYBL1 (X-Y) homologous region (pseudoautosomal region 2, PAR2) at the long arms of the X and Y chromosomes, which clearly confirmed that the breakpoint of the Y chromosome was located within the heterochromatin area of Yq12 outside the AZF a, b or c regions (Figure 2a and b).
Bilateral multiple testicular biopsies revealed almost identical alterations, namely seminiferous tubules with slightly diminished diameters, thickened fibrous membranes, and rarification of germinative epithelial tissues. Within the tubules, one could observe spermatogonia, primary and secondary spermatocytes, but no spermatids or spermatozoa, which led to a diagnosis of maturation arrest of spermatogenesis at the level of secondary spermatocytes (Figure 3).
Figure 2. FISH analysis indicating the breakage point within the Y-heterochromatin outside the AZF region. Note that only part of the Yq12 heterochromatin sequence DYZ1 (a) together with SYBL1 representing PAR2 (b) is translocated onto the long arm of the derivative chromosome 1 [der (1)], while CDY (a) and DAZ (b) remain on the derivative chromosome Y [der (Y)]. Centromeres of der (1), der (Y), and the X chromosome are indicated by bars.
Braun-Falco et al
N
Azoospermia With Translocation Y;1
649
Figure 3. Testicular histology demonstrating an arrest of spermatogenesis at the level of secondary spermatocytes (no spermatids or spermatozoa); hematoxylin and eosin staining, original magnification 4006.
Discussion The patient presented herein with azoospermia and otherwise normal phenotype displayed a de novo reciprocal translocation with breakpoints within the heterochromatic region in Yq12 outside the AZF and at chromosome 1q25. To our knowledge, a t(Y;1) (q12;q25) translocation has not been described to date. We were able to find ten other cases with t(Y;1) translocations in the literature (Table). Two of these aberrations were unbalanced with a familial der(1) t(Y;1) (q12;p36) translocation, which had been transmitted as a chromosomal variant through males and females down several generations without affecting their phenotypes. The male carriers had no reproductive problems, due to a normal Y chromosome, while the women had repeated miscarriages, although they were de facto capable of giving birth (Morel et al, 2002). Two other reports have described young children, primarily with neurological symptoms, who had normal external
genitalia (Narahara et al, 1978; Al-Awadi et al, 1985). The remaining 6 cases and our case demonstrated spermatogenic arrest. The translocation breakpoints in these cases were confined to the long arm of the Y chromosome and were variable at chromosome 1. Two of the Y-breakpoints lay within the euchromatic region at q11, whereas the others were localized to the heterochromatin, and in one case to the telomere region. AZF regions a, b, and c were investigated in 4 cases but no deletions were detected (Maraschio et al, 1994; Pabst et al, 2002; Pinho et al, 2005). Concerning the AZF regions, it has usually been assumed that male infertility results from breakpoints within the AZF regions at Yq11, whereas males are fertile when the breakpoints occur within the heterochromatin (Vogt and Fernandes, 2003). However, the azoospermia in the present case and the 3 cases mentioned above was associated with breakpoints outside the AZF region (Maraschio et al, 1994; Pabst et al, 2002; Pinho et al, 2005) and a fertile
650
Journal of Andrology
N
September October 2007
The cytogenetic and clinical spectrum of (Y;1) translocations* Reference
Karyotype
Y-breakpoint
Origin
Andrological Abnormalities
Narahara, 1978
t(Y,1) (q11;q21), balanced
n.d.
De novo
Normal external genitals of a 4-month-old male
Al-Awadi, 1985
Complex translocation t(Y;1;3) with loss of 3q22Rq24
n.d.
De novo
Normal external genitals
Moreau, 1987
t(Y;1) (q21;p13), balanced
Within heterochromatic region
n.d.
Gregori-Romero, 1990
n.d.
Teyssier, 1993
t(Y;1) (cen-q11;cen-p11) de novo and familial t(Y;15) (q12;p11) t(Y;1) (q11;q11)
Testicular hypotrophy, varicocele, azoospermia with no secondary spermatocytes, Azoospermia
Maraschio, 1994
Pabst, 2002 Morel, 2002
Pinho, 2005
Current case
Sub-centromeric eurchromatin
Familial
t(Y;1)(q12;p34.3) balanced
Telomer-region of the long arm with intact AZF
De novo
t(Y;1)(q11.2;p34.3), balanced t(Y,1)(q12;p36), unbalanced t(Y,1)(q12;p36), unbalanced t(Y;1)(q12;p12), balanced
Euchromatic region with intact AZF
n.d.
t(Y;1) (q12;q25), balanced
Familial Familial Heterchromatic region with intact AZF Intact AZF
De novo
De novo
Other Phenotypes Psychomotoric retardation, myoclonic spasms Developmental delay, mental and growth retardation, microcephaly Hodgkin’s disease
n.d.
Oligozoospermia but fertile; Partial occlusion of testicular duct system Azoospermia, hypotesticles, varicocele, spermatogenic arrest at the spermatocyte stage Cryptozoospermia
None
Fertile, daughter with miscarriage Fertile, daughter with miscarriage Azoospermia at meiosis I
None
Azoospermia with spermatogenic arrest at secondary spermatocyte stage
None
None
None None
None
*n.d., not determined; AZF, azoospermic factor.
male with breakpoint in the Yq11 euchromatic region (Teyssier et al, 1993), which demonstrates that this rule is not applicable to balanced reciprocal (Y,1) translocations. In our clinical case, FISH analysis using a variety of probes for DAZ, CDY, DYZ1, and PAR2 clearly revealed a breakpoint within the heterochromatic region of Yq12. For Y;autosome translocations outside the AZF region, a failure to form the sex vesicle due to unpairing of the Y and X chromosomes has been suggested to inhibit homolog segregation and cause spermatogenic arrest, and eventually spermatocyte degeneration (Delobel et al, 1998; Pabst et al, 2002; Pinho et al, 2005). Since the male-specific region of the Y chromosome has recently been characterized, the detailed information about more than 150 transcription units inside and outside the AZF region will help to identify distinct factors involved in genetic spermatogenic arrest (Skaletsky, 2003). In the (Y;1) translocation, Y breakpoints, as well as breakpoints in chromosome 1 obviously cause azoo-
spermia. A male-specific infertility locus on chromosome 1 has been proposed recently (Bache et al, 2004). A large analysis comparing 464 infertile males to a cohort of 912 individuals with unique rearrangements covering almost all constitutional chromosomal abnormalities, conducted in Denmark over the last 40 years, has revealed a general excess of breakpoints on chromosome 1 associated with infertility. The regions that contributed most to the significant difference in distribution of breakpoints were 1q21, 1q32, 1q24, 1p22, and 1q12 in decreasing number and significance. This contrasts to the chromosome 1 breakpoints in our list of (Y;1) translocations, which were located at 1p11, 1p12, 1q11, 1q25, and twice at 1p34.3, respectively. This inconsistency does not necessarily exclude a pathological role of chromosome 1 in t(Y;1)-related azoospermia, although no concrete explanation currently exists for its influence (Bache et al, 2004). In summary, the present case reveals a new de novo t(Y;1) translocation, with breakpoints in the hetero-
Braun-Falco et al
N
Azoospermia With Translocation Y;1
chromatin of the Y chromosome outside the AZF region and in chromosome 1q25, which is associated with azoospermia.
References Al-Awadi SA, Naguib KK, Farag T, Teebi AS, Cuschieri A, AlOthman SA, Sundareshan TS. Complex translocation involving chromosomes Y, 1, and 3 resulting in deletion of segment 3q23Rq25. J Med Genet. 1985;23:91–92. Bache I, Assche EV, Cingoz S, Bugge M, Tumer Z, et al. An excess of chromosome 1 breakpoints in male infertility. Eur J Hum Genetics. 2004;12:993–1000. Delobel B, Djlelati R, Gabriel-Robez O, Croquette M-F, RousseauxPrevost R, Rousseaux J, Rigot J-M, Rumpler Y. Y-autosome translocation and infertility: usefulness of molecular, cytogenetic and meiotic studies. Hum Genet. 1998;102:98–102. Gregori-Romero M, Lopez-Gines C, Gil R, Galan Sanchez F, PellinPerez A. Dos nuevos casos de translocacion Y-autosoma asociada con azoospermia. Rev Clin Esp. 1990;187:71–73. Hsu LYF. Phenotype/karyotype correlations of Y chromosome aneuploidy with emphasis on structural aberrations in postnatally diagnosed cases. Am J Med Genet. 1994;53:108–140. Maraschio P, Tupler R, Dainotti E, Cortinovis M, Tiepolo L. Molecular analysis of a human Y;1 translocation in an azoospermic male. Cytogenet Cell Genet. 1994;65:256–260. Moreau N, Teyssier M, Rollet J. A new case of (Y;1) balanced reciprocal translocation in an infertile man with Hodgkin’s disease. J Med Genet. 1987;24:379–380.
651 Morel F, Douet-Guilbert N, Le Bris M-J, Amice V, Le Martelot MT, Roche S, Vale´ri A, Derrien V, Amice J, De Braekeleer M. Chromosomal abnormalities in couples undergoing intracytoplasmic sperm injection. A study of 370 couples and review of the literature. Int J Androl. 2004;27:178–182. Morel F, Dugue´pe´roux I, McElreavey K, Le Bris M-J, Herry A, Parent P, Le Martelot M-T, Fellous M, De Braekeleer M. Transmission of an unbalanced (Y;1) translocation in Brittany, France. J Med Genet. 2002;39:e52. Narahara K, Yabuuchi H, Kimura S, Kimoto H. A case of a reciprocal translocation between the Y and No 1 chromosome. Jpn J Hum Genet. 1978;23:225–231. Pabst B, Glaubitz R, Schalk T, Schneider U, Schulze W, Miller K. Reciprocal translocation between Y chromosome long arm euchromatin and the short arm of chromosome 1. Ann Gen. 2002;45:5–8. Pinho MJ, Neves R, Costa P, Ferras C, Sousa M, Alves C, Almeida C, Fernandes S, Silva J, Ferras L, Barros A. Unique t(Y;1) (q12;q12) reciprocal translocation with loss of the heterochromatic region of chromosome 1 in a male with azoospermia due to meiotic arrest: a case report. Hum Reprod. 2005;20:689–696. Skaletsky H, Kuroda-Kawaguchi T, Minx PJ, Cordum HS, Hillier L, et al. The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes. Nature. 2003;423:825–837. Teyssier M, Rafat A, Pugeat M. Case of (Y;1) familial translocation. Am J Med Genet. 1993;46:339–340. Vogt PH, Fernandes S. Polymorphic DAZ gene family in polymorphic structure of AZF locus: artwork or functional for human spermatogenesis? APMIS. 2003;111:115–127. World Health Organization. WHO Laboratory Manual for the Examination of Human Semen and Semen-Cervical Mucus Interaction. New York: Cambridge University Press; 1999.
