Frequency of Y chromosome microdeletions and chromosomal abnormalities in infertile Thai men with oligozoospermia and azoospermia

Aim： To investigate the possible causes of oligozoospermia and azoospermia in infertile Thai men, and to find the frequencies of Y chromosome microdeletions and cytogenetic abnormalities in this group. Methods： From June 2003 to November 2005, 50 azoospermic and 80 oligozoospermic men were enrolled in the study. A detailed history was taken for each man, followed by general and genital examinations. Y chromosome microdeletions were detected by multiplex polymerase chain reaction （PCR） using 11 gene-specific primers that covered all three regions of the azoospermic factor （AZFa, AZFb and AZFc）. Fifty men with normal semen analysis were also studied. Karyotyping was done with the standard G- and Q-banding. Serum concentrations of follicle stimulating hormone （FSH）, luteinizing hormone （LH）, prolactin （PRL） and testosterone were measured by electrochemiluminescence immunoassays （ECLIA）. Results： Azoospermia and oligozoospermia could be explained by previous orchitis in 22.3%, former bilateral cryptorchidism in 19.2%, abnormal karyotypes in 4.6% and Y chromosome microdeletions in 3.8% of the subjects. The most frequent deletions were in the AZFc region （50%）, followed by AZFb （33%） and AZFbc （17%）. No significant difference was detected in hormonal profiles of infertile men, with or without microdeletions. Conclusion： The frequencies of Y chromosome microdeletions and cytogenetic abnormalities in oligozoospermic and azoospermic Thai men are comparable with similarly infertile men from other Asian and Western countries.

The prevalence of azoospermia factor microdeletion on the Y chromosome of Chinese infertile men detected by multi-analyte suspension array technology

Aim： To develop a high-throughput multiplex, fast and simple assay to scan azoospermia factor （AZF） region microdeletions on the Y chromosome and establish the prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. Methods： In total, 178 infertile patients with azoospermia （nonobstructed）, 134 infertile patients with oligozoospermia as well as 40 fertile man controls were included in the present study. The samples were screened for AZF microdeletion using optimized multi-analyte suspension array （MASA） technology. Results： Of the 312 patients, 36 （11.5%） were found to have deletions in the AZF region. The rnicrodeletion frequency was 14% （25/178） in the azoospermia group and 8.2% （11/134） in the oligospermia group. Among 36 patients with microdeletions, 19 had deletions in the AZFc region, seven had deletions in AZFa and six had deletions in AZFb. In addition, four patients had both AZFb and AZFc deletions. No deletion in the AZF region was found in the 40 fertile controls. Conclusion： There is a high prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. The MASA technology, which has been established in the present study, provides a sensitive and high-throughput method for detecting the deletion of the Y chromosome. And the results suggest that genetic screening should be advised to infertile men before starting assisted reproductive treatments.

Y chromosome microdeletions in azoospermic patients with Klinefelter's syndrome

Aim： To study the occurrence of Y chromosome microdeletions in azoospermic patients with Klinefelter＇s syndrome （KFS）. Methods： Blood and semen samples were collected from azoospermic patients with KFS （n = 14） and a control group of men of proven fertility （n = 13）. Semen analysis was done according to World Health Organization （WHO） guidelines. Blood samples were processed for karyotyping, fluorescent in situ hybridization （FISH） and measurement of plasma follicle stimulating hormone （FSH） by radioimmunoassay. To determine Y chromosome microdeletions, polymerase chain reaction （PCR） of 16 sequence tagged sites （STS） and three genes （DFFRY, XKRY and RBM1 Y） was performed on isolated genomic DNA. Testicular fine needle aspiration cytology （FNAC） was done in selected cases. Results： Y chromosome microdeletions spanning the azoospermia factor （AZF）a and AZFb loci were found in four of the 14 azoospermic patients with KFS. Karyotype and FISH analysis revealed that, of the four cases showing Y chromosome microdeletion, three cases had a 47,XXY/46,XY chromosomal pattern and one case had a 46,XY/47,XXY/48,XXXY/48,XXYY chromosomal pattern. The testicular FNAC of one sample with Y chromosome microdeletion revealed Sertoli cell-only type of morphology. However, no Y chromosome microdeletions were observed in any of the 13 fertile men. All patients with KFS had elevated plasma FSH levels. Conclusion： Patients with KFS may harbor Y chromosome microdeletions and screening for these should be a part of their diagnostic work-up, particularly in those considering assisted reproductive techniques. （Asian JAndrol 2006 Jan; 8： 81-88）

Routine screening for classical azoospermia factor deletions of the Y chromosome in azoospermic patients with Klinefelter syndrome

Aim： To evaluate the occurrence of classical azoospermia factor （AZF） deletions of the Y chromosome as a routine examination in azoospermic subjects with Klinefelter syndrome （KS）. Methods： Blood samples were collected from 95 azoospermic subjects with KS （91 subjects had a 47,XXY karyotype and four subjects had a mosaic 47,XXY/46, XY karyotype） and a control group of 93 fertile men. The values of testosterone, follicle stimulating hormone （FSH） and luteinizing hormone （LH） were measured. To determine the presence of Y chromosome microdeletions, polymerase chain reaction （PCR） of five sequence-tagged site primers （sY84, sY 129, sY 134, sY254, sY255） spanning the AZF region, was performed on isolated genomic DNA. Results： Y chromosome microdeletions were not found in any of the 95 azoosperrnic subjects with KS. In addition, using similar conditions of PCR, no microdeletions were observed in the 93 fertile men evaluated. The level of FSH in KS subjects was higher than that in fertile men （38.2 ± 10.3 mIU/mL vs. 5.4 ±2.9 mIU/mL, P 〈 0.001） and the testosterone level was lower than that in the control group （1.7 ±0.3 ng/mL vs. 4.3 ± 1.3 ng/mL, P 〈 0.001）. Conclusion： Our data and review of the published literature suggest that classical AZF deletions might not play a role in predisposing genetic background for the phenotype of azoospermic KS subjects with a 47,XXY karyotype. In addition, routine screening for the classical AZF deletions might not be required for these subjects. Further studies including partial AZFc deletions （e.g. gr/gr or b2/b3） are necessary to establish other mechanism underlying severe spermatogenesis impairment in KS.

Clinical and pathological correlation of the microdeletion of Y chromosome for the 30 patients with azoospermia and severe oligoasthenospermia

Aim: To review the accumulated 30 patients with different area of Y chromosome microdeletions, focusing on their correlation with the clinical and pathological findings. Methods: A total of 334 consecutive infertile men with azoospermia (218 patients) and severe oligoasthenospermia (116 patients) were screened. Complete physical and endocrinological examinations, general chromosome study and multiplex polymerase chain reaction assay to evaluate the Y chromosome microdeletion were performed. Ten patients received testicular biopsy. Then the clinical and pathological findings were analyzed with reference to the areas of Y chromosome microdeletion. Results: There is a decline of the percentage of sperm appearing in semen in the group that the gene deletion region from AZFc to AZFb. The clinical evidence of the impairment (decreased testicular size and elevated serum FSH) is also relevantly aggravated in this group. However, the pathology of testicular biopsy specimen was poorly correlated with the different deletion areas of the Y chromosome, which may be due to the limited number of specimens. Conclusion: The clinical correlation of spermatogenic impairment to the different AZF deletion regions may provide the information for the infertile couples in pre-treatment counseling.

Multiplex PCR Screening of Y Chromosome Microdeletions in Azoospermic Patients

Objective To develop a multiplex PCR protocol for routine screening of microdeletions on the Y chromosome Methods Five multiplex sets were established and Y chromosome microdeletions screening were carried out in 26 azoospermic men who undertook ICSI and 30 azoospermic men who undertook testicular biopsy. Results In 56 azoospermic men, 5 patients were found with AZFc/DAZ microdeletions, 2 patients were accompanied by AZFc/DAZ and AZFb/RBM1 double microdeletion, and 1 patient had only single sY153 microdeletion. Conclusion The multiplex PCR protocol presented in this study is an easy and reliable method for detecting microdeletions on the Y chromosome. Routine screening for microdeletions on the Y chromosome in azoospermic patients is essential.

Screening for Y chromosome microdeletions in idiopathic and nonidiopathic infertile men with varicocele and cryptorchidism

Cytogenetic and molecular studies of azoospermic and oligozoospermic males have suggested the presence of azoospermia factors （AZF） in the Y chromosome. Deletion in AZF regions has been reported to disrupt spermatogenesis and cause infertility. Several candidate genes responsible for spermatogenesis have been identified in this region and some of them are thought to be functional in human spermatogenesis. And we reported clinical and molecular studies of Y chromosome microdeletions in Chinese. This study aimed at assessing the frequency of microdeletions in Chinese men with idiopathic and nonidiopathic infertility problems and dicussing the clinical significance of the AZF region.

Roles of the Y chromosome genes in human cancers

Male and female differ genetically by their respective sex chromosome composition, that is, XY as male and XX as female. Although both X and Y chromosomes evolved from the same ancestor pair of autosomes, the Y chromosome harbors male-specific genes, which play pivotal roles in male sex determination, germ cell differentiation, and masculinization of various tissues. Deletions or translocation of the sex-determining gene, SRY, from the Y chromosome causes disorders of sex development （previously termed as an intersex condition） with dysgenic gonads. Failure of gonadal development results not only in infertility, but also in increased risks of germ cell tumor （GCT）, such as gonadoblastoma and various types of testicular GCT. Recent studies demonstrate that either loss of Y chromosome or ectopic expression of Y chromosome genes is closely associated with various male-biased diseases, including selected somatic cancers. These observations suggest that the Y-linked genes are involved in male health and diseases in more frequently than expected. Although only a small number of protein-coding genes are present in the male-specific region of Y chromosome, the impacts of Y chromosome genes on human diseases are still largely unknown, due to lack of in vivo models and differences between the Y chromosomes of human and rodents. In this review, we highlight the involvement of selected Y chromosome genes in cancer development in men.

Convergence of Y Chromosome STR Haplotypes from Different SNP Haplogroups Compromises Accuracy of Haplogroup Prediction

The paternally inherited Y chromosome has been widely used in forensics for personal identification, in anthropology and population genetics to understand origin and migration of human populations, and also in medical and clinical studies （Wang and Li, 2013; Wang et al., 2014）. There are two kinds of extremely useful markers in Y chromosome, single nucle- otide polymorphism （SNP） and short tandem repeats （STRs）. With a very low mutation rate on the order of 3.0 x 10-8 mutations/nucleotide/generation （Xue et al., 2009）, SNP markers have been used in constructing a robust phylogeny tree linking all the Y chromosome lineages from world pop- ulations （Karafet et al., 2008）. Those lineages determined by the pattern of SNPs are called haplogroups. That is to say, we have to genotype an appropriate number of SNPs in order to assign a given Y chromosome to a haplogroup. Compared with SNPs, the mutation rates of STR markers are about four to five orders of magnitude higher （Gusmgo et al., 2005; Ballantyne et al., 2010）. Typing STR has advantages of saving time and cost compared with typing SNPs in phylogenetic assignment of a Y chromosome （Wang et al., 2010）. A set of STR values for an individual is called a haplotype. Because of the disparity in mutation rates between SNP and STR, one SNP haplogroup could actually comprise many STR haplotypes （Wang et al., 2010）. It is most interesting that STR variability is clustered more by haplogroups than by populations （Bosch et al., 1999; Behar et al., 2004）, which indicates that STR haplotypes could be used to infer the haplogroup information of a given Y chromosome. There has been increasing interest in this cost- effective strategy for predicting the haplogroup from a given STR haplotype when SNP data are unavailable. For instance, Vadim Urasin＇s YPredictor （http：//predictor.ydna.ru/）, Whit Atheys＇ haplogroup predictor （http：//www.hprg.com/hapest5/） （Athey, 2005, 2006）, and haplogroup classifier of Arizona University （Schlecht et al., 2008） have been widely employed in previous studies for haplogroup prediction （Larmuseau et al., 2010; Bembea et al., 2011; Larmuseau et al., 2012; Tarlykov et al., 2013）.

Y chromosome microdeletion screening using a new molecular diagnostic method in 1030 Japanese males with infertility

The azoospermia factor(AZF)region is important for spermatogenesis,and deletions within these regions are a common cause of oligozoospermia and azoospermia.Although several studies have reported this cause,the present research,to the best of our knowledge,is the first large-scale study assessing this factor in Japan.In this study,1030 male patients with infertility who were examined for Y chromosome microdeletion using the polymerase chain reaction-reverse sequence-specific oligonucleotide(PCR-rSSO)method,a newly developed method for Y chromosome microdeletion screening,were included.The study enrolled 250 patients with severe oligospermia and 717 patients with azoospermia.Among the 1030 patients,4,4,10,and 52 had AZFa,AZFb,AZFb+c,and AZFc deletions,respectively.The sperm recovery rate(SRR)of microdissection testicular sperm extraction in patients with AZFc deletions was significantly higher than that in those without AZF deletions(60.0%vs 28.7%,P=0.04).In patients with gr/gr deletion,SRR was 18.7%,which was lower than that in those without gr/gr deletion,but was not statistically significant.In conclusion,our study showed that the frequency of Y chromosome microdeletion in male patients in Japan was similar to that reported in patients from other countries,and SRR was higher in patients with AZFc deletion.

A Hu sheep genome with the first ovine Y chromosome reveal introgression history after sheep domestication

The Y chromosome plays key roles in male fertility and reflects the evolutionary history of paternal lineages.Here,we present a de novo genome assembly of the Hu sheep with the first draft assembly of ovine Y chromosome(o MSY),using nanopore sequencing and Hi-C technologies.The o MSY that we generated spans 10.6 Mb from which 775 Y-SNPs were identified by applying a large panel of whole genome sequences from worldwide sheep and wild Iranian mouflons.Three major paternal lineages(HY1a,HY1b and HY2)were defined across domestic sheep,of which HY2 was newly detected.Surprisingly,HY2 forms a monophyletic clade with the Iranian mouflons and is highly divergent from both HY1a and HY1b.Demographic analysis of Y chromosomes,mitochondrial and nuclear genomes confirmed that HY2 and the maternal counterpart of lineage C represented a distinct wild mouflon population in Iran that diverge from the direct ancestor of domestic sheep,the wild mouflons in Southeastern Anatolia.Our results suggest that wild Iranian mouflons had introgressed into domestic sheep and thereby introduced this Iranian mouflon specific lineage carrying HY2 to both East Asian and Africa sheep populations.

Molecular genetic evidence of Y chromosome loss in male patients with hematological disorders

Background There has been continuous debate as to whether Y chromosome loss is an age related phenomenon or a cytogenetic marker indicating a malignant change. This study aimed to investigate the frequency of Y chromosome loss in the specific patients in order to determine whether it is an age related phenomena or a cytogenetic marker indicating a malignant change. Methods Five hundred and ninety-two male patients with a median age of 59 years old （22-95 years） were included in this study. These patients were divided into two groups： the study group, including 237 patients who had hematological disorders included myeloproliferative disorder （MPD）, myelodysplastic syndrome （MDS）, acute myeloid leukemia （AML）, chronic myeloid leukemia （CML）, multiple myeloma （MM）, and lymphoma and the control group including 355 patients with no evidence of hematological disease. Both conventional cytogenetics and fluorescence in situ hybridization using DNA probes specific for the centromere of chromosomes X or Y were performed according to our standard laboratory protocols. Results Twenty-four out of 237 patients with hematological disorders （10.1%） had Y chromosome loss. Of these 24 patients, 2 patients had AML （5.0% of all AML patients）, 2 patients had CML （5.7% of all CML patients）, 2 patients had MPD （8.0% of all MPD patients）, 3 patients had MM （10.0% of all MM patients）, 5 patients had lymphoma （10.6% of all lymphoma patients） and 10 patients had MDS （16.7% of all MDS patients）. Twenty-one out of these 24 patients had a loss of Y chromosome as the sole anomaly and the remaining three had a loss of Y chromosome accompanied with other structural changes detected by conventional cytogenetic analysis. Fluorescence in situ hybridization （FISH） analysis confirmed the routine cytogenetic results. All 24 patients had a loss of Y chromosome with a range of 17.5%-98.5% of cells. Two of the patients, one with AML and another with CML, had karyotype and FISH testing done both at the initial diagnosis and during remission. The results showed a loss of Y chromosome at initial diagnosis but a normal 46,XY karyotype dunng remission. Only 9 out of 355 patients （2.5%） without evidence of hematological disease had Y chromosome loss, among them 7 patients had cardiovascular diseases and 2 patients had kidney diseases. Comparison of the incidence of Y chromosome loss in patients with hematological disorders or without evidence of hematological disease using statistical analysis showed a statistically significance difference （P〈0.05）. Conclusions The present study demonstrated that the frequency of Y chromosome loss is significantly higher in patients with hematological disorders than in patients without hematological disorders, which indicates that the loss of Y chromosome is associated with a neoplastic change.

Expression of the human TSPY gene in the brains of transgenic mice suggests a potential role of this Y chromosome gene in neural functions

The testis specific protein Y-encoded （TSPY） is a member of TSPY/SET/NAP1 superfamily, encoded within the gonadoblastoma locus on the Y chromosome. TSPY shares a highly conserved SET/NAP-domain responsible for protein--protein interaction among TSPY/SET/NAP 1 proteins. Accumulating data, so far, support the role of TSPYas the gonadoblastoma gene, involved in germ cell tumorigenesis. The X-chromosome homolog of TSPY, TSPX is expressed in various tissues at both fetal and adult stages, including the brain, and is capable of interacting with the multi-domain adapter protein CASK, thereby influencing the synaptic and transcriptional functions and developmental regulation of CASK in the brain and other neural tissues. Similar to TSPX, we demonstrated that TSPY could interact with CASK at its SET/NAP-domain in cultured cells. Transgenic mice harboring a human TSPYgene and flanking sequences showed specific expression of the human TSPYtransgene in both testis and brain. The neural expression pattern of the human TSPYgene overlapped with those of the endogenous mouse Cask and Tspx gene. Similarly with TSPX, TSPY was co-localized with CASK in neuronal axon fibers in the brain, suggesting a potential role（s） of TSPY in development and/or physiology of the nervous system.

Natural Selection on Human Y Chromosomes

In the field of anthropology, the uniparerttally inherited Y chromosome has long been used to trace the paternal lineage of the populations and to understand differences in migration and population genetics between males and females, with additional advantages of small effective population size, suf- ficient markers, and population-specific haplotype distribution （Jobling and Tyler-Smith, 1995; Jin and Su, 2000; Underhill et al., 2000）. Many such population studies have rested on the assumption that all the Y chromosome markers in the non- recombination regions are selectively neutral （Jobling and Tyler-Smith, 2003）.

High risk genetic factor in Chinese patients with idiopathic male infertility: deletion of DAZ gene copy on Y chromosome

Idiopathic azoospermia or oligozoospermia affects approximately 2% -4% of allmarried males. Recently studies have confirmed that the deletion of DAZ in AZFc region of Ychromosome may be one of the important genetic aetiologies of Caucasian male infertility. Todetermine the relationship between DAZ gene deletion and idiopathic male infertility in Chinesepopulation, we analysed the DAZ gene copy number of AZFc region in patients with idiopathicazoospermia or oligozoospermia, as well as fertile Chinese men.

Synteny search identifies carnivore Y chromosome for evolution of male specific genes

The explosive accumulation of mammalian genomes has provided a valuable resource to characterize the evo­lution of the Y chromosome.Unexpectedly,the Y-chromosome sequence has been characterized in only a small handful of species,with the majority being model organisms.Thus,identification of Y-linked scaffolds from un­ordered genome sequences is becoming more important.Here,we used a syntenic-based approach to generate the scaffolds of the male-specific region of the Y chromosome(MSY)from the genome sequence of 6 male car­nivore species.Our results identified 14,15,9,28,14 and 11 Y-linked scaffolds in polar bears,pacific walruses,red pandas,cheetahs,ferrets and tigers,covering 1.55 Mbp,2.62 Mbp,964 Kb,1.75 Mb,2.17 Mbp and 1.84 Mb MSY,respectively.All the candidate Y-linked scaffolds in 3 selected species(red pandas,polar bears and ti­gers)were successfully verified using polymerase chain reaction.We re-annotated 8 carnivore MSYs including these 6 Y-linked scaffolds and domestic dog and cat MSY;a total of 11 orthologous genes conserved in at least 7 of the 8 carnivores were identified.These 11 Y-linked genes have significantly higher evolutionary rates com­pared with their X-linked counterparts,indicating less purifying selection for MSY genes.Taken together,our study shows that the approach of synteny search is a reliable and easily affordable strategy to identify Y-linked scaffolds from unordered carnivore genomes and provides a preliminary evolutionary study for carnivore MSY genes.

Gonadal dysgenesis in Turner syndrome with Y-chromosome mosaicism:Two case reports

BACKGROUND Turner syndrome(TS)has a variety of different karyotypes,with a wide range of phenotypic features,but the specific karyotype may not always predict the phenotype.TS with Y chromosome mosaicism may have mixed gonadal dysgenesis,and the mosaicism is related to the potential for gonadoblastoma.CASE SUMMARY In this case report,we report two cases of TS with different karyotypes and gonadal dysgenesis.Patient 1 had obvious virilization,and was positive for the SRY gene,but her karyotype in peripheral blood lymphocytes was 45X.Patient 2 had a mosaic karyotype,45X/46X,dic(Y:Y)(p11.3:p11.2),and the proportion of Y-bearing cells was 50%in peripheral blood lymphocytes,but the patient had normal female external genitalia and streaky gonads,with no genital virilism.Different tissues in the same TS individual may exhibit different ratios of mosaicism.The gonadal determination and differentiation of mosaic TS are primarily dependent on the predominant cell line in the gonads.CONCLUSION In TS patients with virilization,it is necessary to test at least two to three tissues to search for cryptic Y material.

Origin of modern humans in East Asia:clues from the Y chromosome

East Asia is one of the most important regions for studying modern human origin and evolution.A lot of efforts have been made to detect the genetic diversity and to reconstruct the evolutionary history of East Asians,especially using Y chromosome genetic data,in recent years.The Y chromosome data supports the African origin of modern humans in East Asia and the later migration to East Asia through the southern tropic coastline route,and then the northward migration occurred,leading to peopling of the main continent.The genetic data of the Y chromosome reflects a clear prehistoric evolution and migration course of East Asians.As well,the Y chromosome data of East Asians provides clues to elucidate modern human origins and evolution in the neighboring regions,i.e.America,Oceania and the Pacific Islands.

Effects of age on segregation of the X and Y chromosomes in cultured lymphocytes from Chinese men

Chromosome malsegregation in binucleated lymphocytes is a useful endpoint to evaluate age effect on genetic stability. However, the investigations on chromosome malsegregation in binucleated lymphocytes from Chinese are scarce. In this study, peripheral blood lym- phocytes were collected from 14 old （60-70 years） and 10 young （22-26 years） healthy Chinese men. To detect malsegregation of the sex chromosomes, multi-color fluorescence in situ hybridization （FISH） was performed on binucleated lymphocytes, cytokinesis-blocked by cytochalasin B at the first mitosis after phytohaemagglutinin stimulation. Compared with that in young men, a significant increase in frequencies of loss of chromosome X （9.2± 3.2‰ vs. 1.1 ± 0.9‰, P 〈 0.001） and Y （2.5 ± 1.9‰ vs. 0.2± 0.3‰, P 〈 0.001） was found in old men. Similarly, nondisjunction of chromosome X （16.5± 3.4‰ vs. 3.5 ± 1.1‰, P 〈 0.001） and Y （7.2 ± 2.6‰ vs. 2.4 ± 1.3‰, P 〈 0.001） occurred more frequently in old men than in young men. Regardless of donor＇s age, nondisjunction is more prevalent than loss for both chromosome X and Y. The frequencies of observed simultaneous malsegregation were relatively higher than the expected, suggest- ing an association between malsegregation. These results indicated that in Chinese men, malsegregation of the sex chromosomes increases with age in an associated fashion, and nondisjunction accounts for the majority of spontaneous chromosome malsegregation.

Y-chromosomal microdeletions and partial deletions of the Azoospermia Factor c(AZFc)region in normozoospermic,severe oligozoospermic and azoospermic men in Sri Lanka

Aim： To assess for the first time the occurrence of Y chromosomal microdeletions and partial deletions of the Azoospermia Factor c （AZFc） region in Sri Lankan men and to correlate them with clinical parameters. Methods： In a retrospective study, we analyzed 96 infertile men （78 with non-obstructive azoospermia） and 87 controls with normal spermatogenesis. AZFa, AZFb, AZFc and partial deletions within the AZFc region were analyzed by multiplex polymerase chain reaction （PCR） according to established protocols. Results： No AZFa, AZFb or AZFc deletions were found in the control group. Seven patients in the group of infertile men were found to have deletions as following： one AZFa, two AZFc, two AZFbc and two AZFabc. The relative distribution of these patterns was significantly different compared with that found in the German population. Extension analysis confirmed that the deletions occurred according to the current pathogenic model, gr/gr deletions were found to be equally present both in the patients （n = 4） and in the control group （n = 4）. One b2/b3 deletion was found in the patient group. Conclusion： These results suggest that the frequency and pattern of microdeletions of the Y chromosome in Sri Lankan men are similar to those found in other populations and confirm that gr/gr deletions are not sufficient to cause spermatogenetic failure. （Asian J Androl 2006 Jan; 8： 39-44）