International Journal of

Introduction   
It is clearly obvious that the Y chromosome is necessary for sexual development and spermatogenesis. In 1976, Tiepolo and Zuffardi (1) reported that the long arm of the Y chromosome carried genetic information that is essential for spermatogenesis. The deletions of the long arm of the Y chromosome could result breakdown in spermatogenesis, leading to infertility in human (2).

    The long arm of Y chromosome (Yq), particularly Yq11 .23 region, is considered to be critical for fertility. Macroscopic deletions of Yq11 are often observed in patients with azoospermia although many microdeletions have been implicated as significant causes of infertility. These microdeletions are often observed in the long arm, at the AZF (Azoospermia Factor) locus. Several subregions are distinguished in the AZF locus. In this locus, the structure of the Y-chromosome is rich in repeated palindromes and recombination between two flanking sequences and sharing a high degree of homology leads to various deletions: AZFa, AZFb, AZFc.
     The frequency of these microdeletions differs among different ethnical populations. In a recent study by Ristanovic et al deletions on Y chromosome were detected in 15.6% of cases, and of all cases 64.7% were detected in AZFc region, 17.6% in AZFa region and 17.6% in AZFb region (3). The most frequent deletion, AZFc, is usually associated with milder azoospermia and oligospermia (4).
     Complete deletions of AZFa, AZFb+c and AZFb regions are associated with cases of more severe azoospermia. The testicular histology shows either total lack of germline cells (SCOS, Sertoli cell only syndrome) or arrested maturation of cells from the spermatogenetic cell lineage (5). The main purpose of this study was to determine AZF microdeletions of the Y chromosome among Turkish infertile patients with azoospermia or oligoasthenospermia and their relation with intracytoplasmic sperm injection (ICSI) outcome for these patients. The association between the types of Y chromosome genetic abnormality and various histopathological features were also evaluated.
 
Materials and methods
           
Patients
     348 patients who applied to our ART (Assisted Reproductive Therapy) clinic between May 2006 and May 2007 and had the diagnosis of azoospermia or oligoasthenospermia were investigated retrospectively. An approval from local educational research committee was taken and written informed consents were obtained from all patients by post, prior to study. Twenty patients who had obstructive azoospermia and eighty patients with additional abnormal findings such as clinic varicocele, recurrent urogenital infections, recurrent urogenital surgery or monolateral cryptorchidism were excluded from the study. The remaining 248 patients were searched for Y microdeletions and forty men with normal karyotype presented AZF microdeletions of Y chromosome.
     The patients did not have additional abnormal findings such as clinic varicocele, recurrent urogenital infections or monolateral cryptorchidism. All forty patients were primary infertile. Hormonal parameters and ultrasonographic testicular volume measurements were recorded. Hormonal parameters were studied with Electrochemiluminescence Immunoassay “ECLIA” (Roche, E170, ELECSYS, Mannheim, Germany) on Elecsys and cobas immunoassay analyzers.
     The minimal detectable limit of the assay was 0.12 ng/ml and normal range of assay was 0.80-8.00 ng/ml for total testosterone. The sensitivity of the assay was 0.13 mIU/ml and range of assay was 0.13-200 mIU/ml for FSH (follicle stimulating hormone), inter-assay coefficients of variation sensitivity was %5 for this test.
     The sensitivity of assay was 0.02mIU/ml, range of assay was 0.02-200 m IU/ml, inter-assay coefficients of variation sensitivity was 5% for LH (Luteinizing hormone). Testicular volume was calculated using the ellipsoid formula (volume = 4/3 a·b·c where a, b, and c are the semiaxes of the ellipsoid). We performed ICSI to 13 patients.
     One surgeon performed all TESE procedures via micro dissection technique (6, 7) and one researcher reviewed the pathology of diagnostic biopsies.
     The procedures were performed in conjunction with controlled ovarian stimulation cycles for ICSI via standard long protocol for female partners. Spermatozoa were not cryopreserved and fresh materials were used for ICSI.
 
Y chromosome analysis
     Y chromosome analysis was carried out with a multiplex polymerase chain reaction (PCR) technique on DNA which was extracted from peripheral leukocytes.
     Genomic DNA was extracted from peripheral blood. DNA was subjected to AZF-polymerase chain reaction (PCR) simplex. A multiplex protocol with primers from all the regions was also developed.
     For patients who had failure of amplification of sequence-tagged site (STS) on Y chromosome, multiple primary pairs were used to confirm the absence of each site in a PCR reaction on multiple occasions. Method and primers described in the guideline orginezed by Simoni et al was used (8).
 
Statistical analysis
     SPSS for windows version 11.0 was used for the frequency analysis and p<0.05 was accepted significant.
 
Results
 
     Fourty patients with normal karyotype but AZF microdeletions of Y chromosome were identified.     Mean FSH value for the patients was 20.91±4.01 mIU/ml, mean LH value was 11.71±3.06 and mean total testosterone value was 2.72±0.61.
     Mean testicular volume was calculated as 1.49±0.58 cm³. Twenty of these 40 patients had AZFc microdeletions whereas 5 patients had AZFb, 3 patients had AZFa, 4 patients had AZFb+AZFc and 8 patients had total AZFa+AZFb+AZFc microdeletions (Table I).

Table I. Types of microdeletions, numbers and percentages of patients that had spermium in their ejaculate or TESE material and that achieved pregnancy.


Table II. Sperm count, type of microdeletion, missing gene locus, pathology and treatment applied to patients. (AZF: azoospermia factor, SA: spermatocytic arrest, SC: sertoli cell only, hy: hyalinization, HS: hypospermatogenesis, GA: germ cell aplasia, OAS: oligoastenospermia, TESE: testicular sperm extraction).
 

   The patients were between ages of 24 and 36 years. From these 40 patients, 32 had azoospermia and 8 had oligoasthenospermia in their semen analysis. We achieved spermium from ejaculate or TESE material and applied ICSI to 13 patients. The incidence of Y microdeletion was 11.49 % in all infertile patients (40 of 348 patients). Types of microdeletions, numbers and percentages of patients that had spermium in their ejaculate or TESE material are stated in table I. The pathological results of testicular biopsies are summarized in table II. The patients with total deletions (AZFa+AZFb+AZFc) and only AZFa microdeletions had severe impaired spermatogenesis in pathologic findings and semen analysis.
     Only two of all patients achieved a pregnancy and both had AZFc microdeletion. The patients were able to complete the pregnancy and gave birth to a healthy child. Spermia was obtained from ejaculate from one of these patients and from TESE material from the other patient. He had spermatocytic arrest in testicular pathology. We could not achieve pregnancy from patients with AZFa+b+c, AZFb+c, AZFa, AZFb microdeletions. From AZFa microdeletions, it was also impossible to achieve spermium.
 
Discussion
     Microdeletions of the Y chromosome represent an important cause of male infertility and one of the most frequent genetic etiologies of severe testiculopathy. The development of Y-specific sequence-tagged sites (STS) - based mapping strategy has permitted the rapid screening of a large number of infertile patients for Y chromosome microdeletions (9).
     The incidences of Y chromosome microdeletions in different ethnic populations reveal different results. Y chromosomal abnormality rate is reported to be 2.2% in non-selected group of males with subfertility in a study by Krausz et al (10). It was reported to be 7% in a study by Martinez et al (11) and the deletions were detected in 3.3% of Turkish male patients in a study by Sargin et al (12). In their study, Sargin et al. found that 47 patients had a diagnosis of idiopathic azoospermia (both obstructed and nonobstructed) and 13 had oligozoospermia of all 60 infertile patients with normal karyotype. In our study we determined the incidence of Y microdeletion as 11.49% in infertile male patients.
When we evaluated the pathological features of biopsies most of the biopsy specimens revealed to have sertoli only cell pattern in the cases of AZFa microdeletions, and this finding is consistent with Kamp et al (13). Moreover, no spermium could be found in any of the patients who had AZFa microdeletion which could lead to a conclusion that having AZFa microdeletion caused the worst prognosis for achieving spermium in the ejaculate or TESE material.
     In our study the incidence of AZFb microdeletions was 12.5% among patients with azospermia. AZFb microdeletions of the Y chromosome are rare. Moreover, finding spermium is also rare from TESE material from the ones having AZFb microdeletion. In our study we could achieve spermium only from two patients with AZFb (5%). In addition, the histological findings revealed a severe impared semen analysis which concurs well with the literature. It is now well established by histological analysis that complete microdeletion of AZFb region usually results in severe spermatogenesis impairment, leading to azoospermia. Complete AZFb deletion is generally associated with a maturation arrest, frequently but not exclusively at the spermatocyte stage. It is characterized by the presence of spermatogonia and spermatocytes, but no postmeiotic germ cells are found in the majority of the tubules (14).
     In general, testis histology of patients with complete deletions of the AZFa region and/or the AZFb region reveals a complete Sertoli cell-only syndrome (SCOS), while testis histology of patients with partial AZFa and AZFb deletions or with AZFc deletions can result in a broad array of testicular phenotypes ranging from complete SCOS or spermatogenetic arrest to hypospermatogenesis (15).
     Consistent with the literature through our findings, AZFc microdeletion was the most frequent type of Y microdeletion and had the best prognosis for achieving spermium among the patients with azopermia (4, 9, 16). We determined a spectrum of histologies in the specimens of patients with AZFc deletions. AZFc deletions are known to be associated with a heterogeneous histological profile, varying from SCO-syndrome to spermatogenic arrest and hypospermatogenesis (17) and the seminal parameters range between azoospermia and oligozoospermia. Oates et al (18) could not even discern a correlation between AZFc deletions and testicular histology. This is not surprising, because most men with nonobstructive azoospermia have a heterogeneous pattern of spermatogenesis.
     We determined mixed AZF microdeletions in twelve patients (four with AZFb+ AZFc and eight with AZFa+ AZFb+ AZFc). The pathologic findings revealed SCOS predominantly but also spermatocytic arrest and hypospermatogenesis areas were also determined.
     Based on these results we can conclude that AZFa microdeletions have the worst prognosis for the possibility of finding spermium in ejaculate or TESE material and consequently the poorest prognosis in ICSI outcome.  In contrary, AZFc microdeletions provide the best results for achieving spermium and pregnancy. These results also concur well with the literature (19). Men with AZFc deletion are somatically healthy, will most likely have useable sperm and chance to experience biological paternity (18). Vertical transmission of AZF deletions from father to son by ICSI was demonstrated in several studies examining larger populations of AZF deleted male (19,20). Thus genetic inheritance should also be taken into consideration in the cases of ICSI conceived sons.
In our study, we could not find an absolute correlation between diagnostic testicular biopsy findings and type of microdeletion, nor even between biopsy findings and TESE success. TESE may not always be successful in patients with non-obstructive azoospermia, as targeting a focus of active spermatogenesis site is not always possible.   Previous several studies have indicated that a single random biopsy cannot reliably predict sperm retrieval with TESE (20).
     The pathologic scan of the TESE material does not give exact information about all testicular tissue. Testis histology could not predict oligospermia or azoospermia, nor could they predict whether sperm could be found in TESE material (18). But in our study we used microTESE, therefore, the possibility of finding spermium and achieving more uniform pathologic findings increased. However, still the pathologic parameters did not correlate with the possibility of achieving spermium.
     Through assisted reproductive technology, men with Y microdeletions and severe oligozoospermia or azoospermia became capable of reproducing. The age, clinic parameters, hormonal assessments and histological evaluations are not enough to describe testicular failure in patients with Y microdeletions. As the type AZF deletions provide an important estimation for ICSI outcome, we point out the importance of genetic testing and counselling regarding Y chromosome microdeletion for couples requesting ICSI. A combination of these parameters should be used to increase the possibility of finding spermium and the chance to undergo ICSI.