- Email: [email protected]
Preliminary study of the relationship between DAZ gene copy deletions and spermatogenic impairment in Chinese men
CORRESPONDENCE Preliminary study of the relationship between DAZ gene copy deletions and spermatogenic impairment in Chinese men Copy deletion screening of DAZ gene family on the Y chromosome in 485 patients with idiopathic azoospermia or oligozoospermia and 236 fertile men revealed that the prevalence of deletion patterns of the entire DAZ gene and DAZ1/DAZ2 gene were significantly higher in the patients than in fertile men. The deletion patterns correlate with spermatogenic impairment in a Chinese population. (Fertil Steril威 2006;85: 1061–3. ©2006 by American Society for Reproductive Medicine.)
Spermatogenic impairment is a primary etiology of male infertility, in which genetic abnormalities play an important role. In 1976, according to the results from cytogenetic analysis of azoospermic patients the azoospermia factor (AZF) locus was mapped to Yq11.2 (1). Subsequent studies have confirmed that deletion of the AZF locus is the second most frequent genetic cause after chromosomal abnormalities and accounts for ⬃10% cases with azoospermia or oligozoospermia (2, 3). In the three regions of AZF locus defined by Vogt et al. in 1996 (2), AZFc region is remarkable for it contains 12 genes and a total of 32 gene copies, most of which express exclusively in testicular tissue and the deletion of this region is the most frequent AZF deletion in infertile men (4, 5). In 1995, DAZ (deleted in azoospermia) gene was first isolated as a candidate gene for spermatogenesis in AZFc. The gene encodes an RNA-binding protein and has four copies in most cases (6, 7). DAZ was transposed to the AZFc region ⬃35 million years ago from its ancestor gene DAZ-Like 1 (DAZL1) located on 3p25, which is an essential gene for normal spermatogenesis in animals (8). Although the function of DAZ is not clear yet, the human DAZ transgene can partially rescue spermatogenesis in Dazl null mouse (9), indicating a spermatogenic role of the gene, and this is also consistent with the observation that men with all DAZ copies deleted in AZFc suffer from azoospermia or oligozoospermia. Further studies on partial DAZ copy deletion indicated that DAZ1/DAZ2 doublet deReceived March 22, 2005; revised and accepted September 12, 2005. Supported by National High Technology Research and Development Program, grants 2002BA711A08 and 2004AA216090, P.R. China; National Natural Science Foundation of China, grant 30371491, P.R. China; Population and Family Planning Committee Foundation of Sichuan Province, grant 200149, P.R. China; and the China Medical Board Foundation. Reprint requests: Prof. Sizhong Zhang, Department of Medical Genetics, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, P.R. China (FAX: 86-28-85164009; E-mail: [email protected]).
0015-0282/06/$32.00 doi:10.1016/j.fertnstert.2005.09.025
letion is another common deletion pattern with the prevalence of 8%–10% in infertile men and may cause spermatogenic impairment (10, 11). In recent years, with the understanding that the AZFc region consists of high homologous repetitive sequences named amplicons, many studies on sequence-tagged sites with or without single nucleotide variant (SNV) focused on the mechanism and precise size of AZFc deletions. At present, at least six different deletion patterns of AZFc have been reported, four of which resulted from homologous recombination between amplicons and the rest are caused by inversion. It has been found that the deletion of b2/b4 removes the entire AZFc with all copies of the DAZ gene and strongly associates with spermatogenic impairment (5, 6, 12, 13), whereas in partial AZFc deletions the gr/gr deletion is more common, and the missing DAZ1/DAZ2 also represents a risk factor for spermatogenic impairment (4, 14, 15). More recently, three novel rare patterns of partial AZFc deletion have been reported in infertile men, two of them remove partial copies of DAZ, yet the exact extension deleted has not been determined (16). Although the genetic effect of the DAZ gene on spermatogenesis is not understood completely, results of these studies imply that the DAZ gene family is the most important candidate responsible for the AZFc deletion phenotype. Because the prevalence and phenotype of the DAZ copy deletion are variable depending on the different Y chromosome haplogroups throughout the world, studies in populations of different origin may provide more evidence for the effect of the number of DAZ copy on spermatogenesis (16, 17). Although China is the most populous country in the world, the DAZ copy deletion have not yet been studied systematically in Chinese. Therefore the present study was aimed to analyze the patterns of DAZ gene deletion in the Chinese population and their relationship with spermatogenic impairment.
Fertility and Sterility姞 Vol. 85, No. 4, April 2006 Copyright ©2006 American Society for Reproductive Medicine, Published by Elsevier Inc.
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TABLE 1 Haplotype frequencies of DAZ gene copy deletion in infertile and fertile men. Fertile men
DAZ2 DAZ4 DAZ1/2 DAZ2/4 DAZ3/4 DAZ2/3/4 DAZ1/2/3 All DAZ copies
P valuea
Infertile men
Total (n ⴝ 236)
Total (n ⴝ 485)
Azoospermic men (n ⴝ 267)
Oligozoospermic men (n ⴝ 218)
[1]
[2]
[3]
60 (25.4) 12 (5.1) 7 (3.0) 2 (0.8) 10 (4.2) 0 0 0
133 (27.4) 42 (8.7) 42 (8.7) 3 (0.6) 39 (8.0) 3 (0.6) 3 (0.6) 42 (8.7)
82 (30.7) 29 (10.9) 24 (9.0) 2 (0.75) 23 (8.6) 2 (0.7) 1 (0.4) 17 (6.4)
51 (23.4) 13 (6.0) 18 (8.3) 1 (0.5) 16 (7.3) 1 (0.5) 2 (0.9) 25 (11.5)
.5695 .0870 .0044 .8960 .0807 ND ND .0000
.1886 .0181 .0051 .7047 .0479 ND ND .0001
.6152 .6818 .0135 .9450 .1552 ND ND .0000
Note: Data are presented as n (%); ND ⫽ Not determined due to low frequency. a Fertile men vs. [1] total infertile men, [2] azoospermic men, and [3] oligozoospermic men. Yang. DAZ gene copy deletion in Chinese men. Fertil Steril 2006.
Four hundred eighty-five infertile men, aged 21–37 years, with azoospermia (n ⫽ 267) or oligozoospermia (n ⫽ 218) were recruited from West China Hospital, Sichuan University and Sichuan Institute of Reproductive Health from 2000 through 2004. Semen analyses were performed three times according to the World Health Organization criteria and all oligozoospermic patients had sperm count less than 10 ⫻ 106/mL. Patients with vas deferens obstruction, chromosomal abnormalities, or microdeletions of AZFa or AZFb were excluded (18). Among the 236 fertile control men, 37 were fathers of the patients, and the rest fathered at least one child naturally. The study was approved by the Institutional Ethical Review Board of West China Hospital, Sichuan University, and signed informed consent forms were obtained from all subjects studied. All gene analyses were performed with genomic DNA extracted from peripheral blood lymphocytes using DNA isolation kits (TaKaRa Co, Otsu, Japan). For each subject, DAZ-specific sequence-tagged sites sY254 and sY255 were used to amplify the DAZ-specific region to determine whether all the DAZ copies were deleted. Complete deletion could be assured if both sY254 and sY255 failed to be amplified in two repetitive tests and the internal control fragment of ZFY (zinc finger protein Y-linked) gene was amplified. If DAZ-specific markers sY254 and sY255 gave normal amplification results, then possible partial deletion of DAZ gene copies was screened with DAZ sequence family variants analysis in SNV sites including SNV-I, SNV-II, SNV-III, SNV-IV, and SNV-V by denaturing high performance liquid chromatography (HPLC) on WAVE System (Transgenomics, Omaha, NE). For optimal heteroduplex separation under partial DNA denaturation the oven temperature was selected according to WAVEMAKE Soft1062
Yang et al.
Correspondence
ware Version 4.1. After denaturing HPLC analysis, the samples with homozygous elution profile of SNVs including SNVI–VI were picked out for further polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) test and routine PCR of DAZ1⫹4 and Y-DAZ3 to determine which DAZ copy was deleted. The accession numbers of these loci in GenBank are G73167 for SNV-I, G73166 for SNV-II, G63907 for SNV-III, G73168 for SNVIV, G63908 for SNV-V, G73169 for SNV-VI, G75623 for DAZ1⫹4, and G73170 for Y-DAZ3 (11). As a result of routine PCR, denaturing HPLC, and PCRRFLP analyses, eight copy deletion haplotypes of DAZ gene were identified and their prevalence in infertile and fertile men was obtained (Table 1). As shown in Table 1 the entire DAZ gene deletion is one of the most frequent patterns responsible for spermatogenic impairment of infertile men. With the DNA features of AZFc region in mind (5), we suggest that the homologous recombination between amplicons b2 and b4 is the major event leading to these entire DAZ gene deletions. The DAZ1/DAZ2 deletion was another frequent deletion pattern observed in the infertile men, suggesting that it might also associate with spermatogenic impairment as previously reported. According to the mechanisms of partial AZFc deletion, most DAZ1/DAZ2 deletions result from the gr/gr deletion with removal of other gene copies (14, 15). The deletion of three DAZ gene copies was rarely reported and the mechanism of such partial AZFc deletion was difficult to explain (10, 11). In present study the deletions of DAZ1/DAZ2/DAZ3 and DAZ2/DAZ3/DAZ4 were rare and found only in patients. However, the presence and genetic effect of such deletion patterns should not Vol. 85, No. 4, April 2006
be ignored when taking into account the dose– effect of the gene. Attention should be paid also to the possible characteristic haplogroups in Chinese men. In the present study we noticed a significant difference of the deletion frequencies of DAZ4 and DAZ3/DAZ4 between fertile and azoospermic men, which was not reported in other population studies. However, no difference of frequencies was found between fertile and oligozoospermic men. Other investigators observed that haplotypes with partial copy deletion of the DAZ gene were more likely to be polymorphisms of the Y chromosome and had little or no effect on spermatogenesis. In summary, we report the patterns and distribution of DAZ copy deletions in Chinese men and demonstrate that the deletions of the entire DAZ gene or the DAZ1/DAZ2 cluster are associated with impaired spermatogenesis. Further investigations are needed to clarify whether DAZ deletions alone, or in combination with other gene deletions, are important for spermatogenesis impairment, and to understand the effect of certain partial AZFc deletions on spermatogenic function (16, 19). To achieve this, further analyses of the deletion of AZFc-specific sequence-tagged sites and new partial deletion patterns in Chinese men are necessary. Yuan Yang, M.D.a Cuiying Xiao, M.D., Ph.D.a Sizhong Zhang, M.D.a Zhoucun A, Ph.D.a Xiang Li, M.D.b Sixiao Zhang, M.D.b a Department of Medical Genetics, West China Hospital, Sichuan University; Division of Human Morbid Genomics, National Key Laboratory of Biotherapy of Human Diseases and b Department of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan, People’s Republic of China REFERENCES 1. Tiepolo L, Zuffardi O. Localization of factors controlling spermatogenesis in the nonfluorescent portion of the human Y chromosome long arm. Hum Genet 1976;34:119 –24. 2. Vogt PH, Edelmann A, Kirsch S, Henegariu O, Hirschmann P, Kiesewetter F, et al. Human Y chromosome azoospermia factors (AZF) mapped to different subregions in Yq11. Hum Mol Genet 1996;5:933– 43.
Fertility and Sterility姞
3. Lanfranco F, Kamischke A, Zitzmann M, Nieschlag E. Klinefelter’s syndrome. Lancet 2004;364:273– 83. 4. Repping S, Skaletsky H, Brown L, van Daalen SK, Korver CM, Pyntikova T, et al. Polymorphism for a 1.6-Mb deletion of the human Y chromosome persists through balance between recurrent mutation and haploid selection. Nat Genet 2003;35:247–51. 5. Kuroda-Kawaguchi T, Skaletsky H, Brown LG, Minx PJ, Cordum HS, Waterston RH, et al. The AZFc region of the Y chromosome features massive palindromes and uniform recurrent deletions in infertile men. Nat Genet 2001;29:279 – 86. 6. Reijo R, Lee TY, Salo P, Alagappan R, Brown LG, Rosenberg M, et al. Diverse spermatogenic defects in humans caused by Y chromosome deletions encompassing a novel RNA-binding protein gene. Nat Genet 1995;10:383–93. 7. Saxena R, de Vries JW, Repping S, Alagappan RK, Skaletsky H, Brown LG, et al. Four DAZ genes in two clusters found in the AZFc region of the human Y chromosome. Genomics 2000;67:256 – 67. 8. Seboun E, Barbaux S, Bourgeron T, Nishi S, Agulnik A, Egashira M, et al. Gene sequence, localization, and evolutionary conservation of DAZLA, a candidate male sterility gene. Genomics 1997;41:227–35. 9. Slee R, Grimes B, Speed RM, Taggart M, Maguire SM, Ross A, et al. A human DAZ transgene confers partial rescue of the mouse DAZ1 null phenotype. Proc Natl Acad Sci USA 1999;96:8040 –5. 10. de Vries JW, Hoffer MJ, Repping S, Hoovers JM, Leschot NJ, van der Veen F. Reduced copy number of DAZ genes in subfertile and infertile men. Fertil Steril 2002;77:68 –75. 11. Fernandes S, Huellen K, Goncalves J, Dukal H, Zeisler J, Rajpert De Meyts E, et al. High frequency of DAZ1/DAZ2 gene deletions in patients with severe oligozoospermia. Mol Hum Reprod 2002;8:286 –98. 12. Foresta C, Moro E, Ferlin A. Y chromosome microdeletions and alterations of spermatogenesis. Endocrinol Rev 2001;22:226 –39. 13. Repping S, Skaletsky H, Lange J, Silber S, Van Der Veen F, Oates RD, et al. Recombination between palindromes P5 and P1 on the human Y chromosome causes massive deletions and spermatogenic failure. Am J Hum Genet 2002;71:906 –22. 14. Ferlin A, Tessari A, Ganz F, Marchina E, Barlati S, Garolla A, et al. Association of partial AZFc region deletions with spermatogenic impairment and male infertility. J Med Genet 2005;42:209 –13. 15. de Llanos M, Ballesca JL, Gazquez C, Margarit E, Oliva R. High frequency of gr/gr chromosome Y deletions in consecutive oligozoospermic ICSI candidates. Hum Reprod 2005;20:216 –20. 16. Hucklenbroich K, Gromoll J, Heinrich M, Hohoff C, Nieschlag E, Simoni M. Partial deletions in the AZFc region of the Y chromosome occur in men with impaired as well as normal spermatogenesis. Hum Reprod 2005;20:191–7. 17. Fernandes S, Paracchini S, Meyer LH, Floridia G, Tyler-Smith C, Vogt PH. A large AZFc deletion removes DAZ3/DAZ4 and nearby genes from men in Y haplogroup N. Am J Hum Genet 2004;74: 180 –7. 18. Simoni M, Bakker E, Krausz C. EAA/EMQN best practice guidelines for molecular diagnosis of Y-chromosomal microdeletions. State of the art 2004. Int J Androl 2004;27:240 –9. 19. Machev N, Saut N, Longepied G, Terriou P, Navarro A, Levy N, et al. Sequence family variant loss from the AZFc interval of the human Y chromosome, but not gene copy loss, is strongly associated with male infertility. J Med Genet 2004;41:814 –25.
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Spermatogenic impairment is a primary etiology of male infertility, in which genetic abnormalities play an important role. In 1976, according to the results from cytogenetic analysis of azoospermic patients the azoospermia factor (AZF) locus was mapped to Yq11.2 (1). Subsequent studies have confirmed that deletion of the AZF locus is the second most frequent genetic cause after chromosomal abnormalities and accounts for ⬃10% cases with azoospermia or oligozoospermia (2, 3). In the three regions of AZF locus defined by Vogt et al. in 1996 (2), AZFc region is remarkable for it contains 12 genes and a total of 32 gene copies, most of which express exclusively in testicular tissue and the deletion of this region is the most frequent AZF deletion in infertile men (4, 5). In 1995, DAZ (deleted in azoospermia) gene was first isolated as a candidate gene for spermatogenesis in AZFc. The gene encodes an RNA-binding protein and has four copies in most cases (6, 7). DAZ was transposed to the AZFc region ⬃35 million years ago from its ancestor gene DAZ-Like 1 (DAZL1) located on 3p25, which is an essential gene for normal spermatogenesis in animals (8). Although the function of DAZ is not clear yet, the human DAZ transgene can partially rescue spermatogenesis in Dazl null mouse (9), indicating a spermatogenic role of the gene, and this is also consistent with the observation that men with all DAZ copies deleted in AZFc suffer from azoospermia or oligozoospermia. Further studies on partial DAZ copy deletion indicated that DAZ1/DAZ2 doublet deReceived March 22, 2005; revised and accepted September 12, 2005. Supported by National High Technology Research and Development Program, grants 2002BA711A08 and 2004AA216090, P.R. China; National Natural Science Foundation of China, grant 30371491, P.R. China; Population and Family Planning Committee Foundation of Sichuan Province, grant 200149, P.R. China; and the China Medical Board Foundation. Reprint requests: Prof. Sizhong Zhang, Department of Medical Genetics, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, P.R. China (FAX: 86-28-85164009; E-mail: [email protected]).
0015-0282/06/$32.00 doi:10.1016/j.fertnstert.2005.09.025
letion is another common deletion pattern with the prevalence of 8%–10% in infertile men and may cause spermatogenic impairment (10, 11). In recent years, with the understanding that the AZFc region consists of high homologous repetitive sequences named amplicons, many studies on sequence-tagged sites with or without single nucleotide variant (SNV) focused on the mechanism and precise size of AZFc deletions. At present, at least six different deletion patterns of AZFc have been reported, four of which resulted from homologous recombination between amplicons and the rest are caused by inversion. It has been found that the deletion of b2/b4 removes the entire AZFc with all copies of the DAZ gene and strongly associates with spermatogenic impairment (5, 6, 12, 13), whereas in partial AZFc deletions the gr/gr deletion is more common, and the missing DAZ1/DAZ2 also represents a risk factor for spermatogenic impairment (4, 14, 15). More recently, three novel rare patterns of partial AZFc deletion have been reported in infertile men, two of them remove partial copies of DAZ, yet the exact extension deleted has not been determined (16). Although the genetic effect of the DAZ gene on spermatogenesis is not understood completely, results of these studies imply that the DAZ gene family is the most important candidate responsible for the AZFc deletion phenotype. Because the prevalence and phenotype of the DAZ copy deletion are variable depending on the different Y chromosome haplogroups throughout the world, studies in populations of different origin may provide more evidence for the effect of the number of DAZ copy on spermatogenesis (16, 17). Although China is the most populous country in the world, the DAZ copy deletion have not yet been studied systematically in Chinese. Therefore the present study was aimed to analyze the patterns of DAZ gene deletion in the Chinese population and their relationship with spermatogenic impairment.
Fertility and Sterility姞 Vol. 85, No. 4, April 2006 Copyright ©2006 American Society for Reproductive Medicine, Published by Elsevier Inc.
1061
TABLE 1 Haplotype frequencies of DAZ gene copy deletion in infertile and fertile men. Fertile men
DAZ2 DAZ4 DAZ1/2 DAZ2/4 DAZ3/4 DAZ2/3/4 DAZ1/2/3 All DAZ copies
P valuea
Infertile men
Total (n ⴝ 236)
Total (n ⴝ 485)
Azoospermic men (n ⴝ 267)
Oligozoospermic men (n ⴝ 218)
[1]
[2]
[3]
60 (25.4) 12 (5.1) 7 (3.0) 2 (0.8) 10 (4.2) 0 0 0
133 (27.4) 42 (8.7) 42 (8.7) 3 (0.6) 39 (8.0) 3 (0.6) 3 (0.6) 42 (8.7)
82 (30.7) 29 (10.9) 24 (9.0) 2 (0.75) 23 (8.6) 2 (0.7) 1 (0.4) 17 (6.4)
51 (23.4) 13 (6.0) 18 (8.3) 1 (0.5) 16 (7.3) 1 (0.5) 2 (0.9) 25 (11.5)
.5695 .0870 .0044 .8960 .0807 ND ND .0000
.1886 .0181 .0051 .7047 .0479 ND ND .0001
.6152 .6818 .0135 .9450 .1552 ND ND .0000
Note: Data are presented as n (%); ND ⫽ Not determined due to low frequency. a Fertile men vs. [1] total infertile men, [2] azoospermic men, and [3] oligozoospermic men. Yang. DAZ gene copy deletion in Chinese men. Fertil Steril 2006.
Four hundred eighty-five infertile men, aged 21–37 years, with azoospermia (n ⫽ 267) or oligozoospermia (n ⫽ 218) were recruited from West China Hospital, Sichuan University and Sichuan Institute of Reproductive Health from 2000 through 2004. Semen analyses were performed three times according to the World Health Organization criteria and all oligozoospermic patients had sperm count less than 10 ⫻ 106/mL. Patients with vas deferens obstruction, chromosomal abnormalities, or microdeletions of AZFa or AZFb were excluded (18). Among the 236 fertile control men, 37 were fathers of the patients, and the rest fathered at least one child naturally. The study was approved by the Institutional Ethical Review Board of West China Hospital, Sichuan University, and signed informed consent forms were obtained from all subjects studied. All gene analyses were performed with genomic DNA extracted from peripheral blood lymphocytes using DNA isolation kits (TaKaRa Co, Otsu, Japan). For each subject, DAZ-specific sequence-tagged sites sY254 and sY255 were used to amplify the DAZ-specific region to determine whether all the DAZ copies were deleted. Complete deletion could be assured if both sY254 and sY255 failed to be amplified in two repetitive tests and the internal control fragment of ZFY (zinc finger protein Y-linked) gene was amplified. If DAZ-specific markers sY254 and sY255 gave normal amplification results, then possible partial deletion of DAZ gene copies was screened with DAZ sequence family variants analysis in SNV sites including SNV-I, SNV-II, SNV-III, SNV-IV, and SNV-V by denaturing high performance liquid chromatography (HPLC) on WAVE System (Transgenomics, Omaha, NE). For optimal heteroduplex separation under partial DNA denaturation the oven temperature was selected according to WAVEMAKE Soft1062
Yang et al.
Correspondence
ware Version 4.1. After denaturing HPLC analysis, the samples with homozygous elution profile of SNVs including SNVI–VI were picked out for further polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) test and routine PCR of DAZ1⫹4 and Y-DAZ3 to determine which DAZ copy was deleted. The accession numbers of these loci in GenBank are G73167 for SNV-I, G73166 for SNV-II, G63907 for SNV-III, G73168 for SNVIV, G63908 for SNV-V, G73169 for SNV-VI, G75623 for DAZ1⫹4, and G73170 for Y-DAZ3 (11). As a result of routine PCR, denaturing HPLC, and PCRRFLP analyses, eight copy deletion haplotypes of DAZ gene were identified and their prevalence in infertile and fertile men was obtained (Table 1). As shown in Table 1 the entire DAZ gene deletion is one of the most frequent patterns responsible for spermatogenic impairment of infertile men. With the DNA features of AZFc region in mind (5), we suggest that the homologous recombination between amplicons b2 and b4 is the major event leading to these entire DAZ gene deletions. The DAZ1/DAZ2 deletion was another frequent deletion pattern observed in the infertile men, suggesting that it might also associate with spermatogenic impairment as previously reported. According to the mechanisms of partial AZFc deletion, most DAZ1/DAZ2 deletions result from the gr/gr deletion with removal of other gene copies (14, 15). The deletion of three DAZ gene copies was rarely reported and the mechanism of such partial AZFc deletion was difficult to explain (10, 11). In present study the deletions of DAZ1/DAZ2/DAZ3 and DAZ2/DAZ3/DAZ4 were rare and found only in patients. However, the presence and genetic effect of such deletion patterns should not Vol. 85, No. 4, April 2006
be ignored when taking into account the dose– effect of the gene. Attention should be paid also to the possible characteristic haplogroups in Chinese men. In the present study we noticed a significant difference of the deletion frequencies of DAZ4 and DAZ3/DAZ4 between fertile and azoospermic men, which was not reported in other population studies. However, no difference of frequencies was found between fertile and oligozoospermic men. Other investigators observed that haplotypes with partial copy deletion of the DAZ gene were more likely to be polymorphisms of the Y chromosome and had little or no effect on spermatogenesis. In summary, we report the patterns and distribution of DAZ copy deletions in Chinese men and demonstrate that the deletions of the entire DAZ gene or the DAZ1/DAZ2 cluster are associated with impaired spermatogenesis. Further investigations are needed to clarify whether DAZ deletions alone, or in combination with other gene deletions, are important for spermatogenesis impairment, and to understand the effect of certain partial AZFc deletions on spermatogenic function (16, 19). To achieve this, further analyses of the deletion of AZFc-specific sequence-tagged sites and new partial deletion patterns in Chinese men are necessary. Yuan Yang, M.D.a Cuiying Xiao, M.D., Ph.D.a Sizhong Zhang, M.D.a Zhoucun A, Ph.D.a Xiang Li, M.D.b Sixiao Zhang, M.D.b a Department of Medical Genetics, West China Hospital, Sichuan University; Division of Human Morbid Genomics, National Key Laboratory of Biotherapy of Human Diseases and b Department of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan, People’s Republic of China REFERENCES 1. Tiepolo L, Zuffardi O. Localization of factors controlling spermatogenesis in the nonfluorescent portion of the human Y chromosome long arm. Hum Genet 1976;34:119 –24. 2. Vogt PH, Edelmann A, Kirsch S, Henegariu O, Hirschmann P, Kiesewetter F, et al. Human Y chromosome azoospermia factors (AZF) mapped to different subregions in Yq11. Hum Mol Genet 1996;5:933– 43.
Fertility and Sterility姞
3. Lanfranco F, Kamischke A, Zitzmann M, Nieschlag E. Klinefelter’s syndrome. Lancet 2004;364:273– 83. 4. Repping S, Skaletsky H, Brown L, van Daalen SK, Korver CM, Pyntikova T, et al. Polymorphism for a 1.6-Mb deletion of the human Y chromosome persists through balance between recurrent mutation and haploid selection. Nat Genet 2003;35:247–51. 5. Kuroda-Kawaguchi T, Skaletsky H, Brown LG, Minx PJ, Cordum HS, Waterston RH, et al. The AZFc region of the Y chromosome features massive palindromes and uniform recurrent deletions in infertile men. Nat Genet 2001;29:279 – 86. 6. Reijo R, Lee TY, Salo P, Alagappan R, Brown LG, Rosenberg M, et al. Diverse spermatogenic defects in humans caused by Y chromosome deletions encompassing a novel RNA-binding protein gene. Nat Genet 1995;10:383–93. 7. Saxena R, de Vries JW, Repping S, Alagappan RK, Skaletsky H, Brown LG, et al. Four DAZ genes in two clusters found in the AZFc region of the human Y chromosome. Genomics 2000;67:256 – 67. 8. Seboun E, Barbaux S, Bourgeron T, Nishi S, Agulnik A, Egashira M, et al. Gene sequence, localization, and evolutionary conservation of DAZLA, a candidate male sterility gene. Genomics 1997;41:227–35. 9. Slee R, Grimes B, Speed RM, Taggart M, Maguire SM, Ross A, et al. A human DAZ transgene confers partial rescue of the mouse DAZ1 null phenotype. Proc Natl Acad Sci USA 1999;96:8040 –5. 10. de Vries JW, Hoffer MJ, Repping S, Hoovers JM, Leschot NJ, van der Veen F. Reduced copy number of DAZ genes in subfertile and infertile men. Fertil Steril 2002;77:68 –75. 11. Fernandes S, Huellen K, Goncalves J, Dukal H, Zeisler J, Rajpert De Meyts E, et al. High frequency of DAZ1/DAZ2 gene deletions in patients with severe oligozoospermia. Mol Hum Reprod 2002;8:286 –98. 12. Foresta C, Moro E, Ferlin A. Y chromosome microdeletions and alterations of spermatogenesis. Endocrinol Rev 2001;22:226 –39. 13. Repping S, Skaletsky H, Lange J, Silber S, Van Der Veen F, Oates RD, et al. Recombination between palindromes P5 and P1 on the human Y chromosome causes massive deletions and spermatogenic failure. Am J Hum Genet 2002;71:906 –22. 14. Ferlin A, Tessari A, Ganz F, Marchina E, Barlati S, Garolla A, et al. Association of partial AZFc region deletions with spermatogenic impairment and male infertility. J Med Genet 2005;42:209 –13. 15. de Llanos M, Ballesca JL, Gazquez C, Margarit E, Oliva R. High frequency of gr/gr chromosome Y deletions in consecutive oligozoospermic ICSI candidates. Hum Reprod 2005;20:216 –20. 16. Hucklenbroich K, Gromoll J, Heinrich M, Hohoff C, Nieschlag E, Simoni M. Partial deletions in the AZFc region of the Y chromosome occur in men with impaired as well as normal spermatogenesis. Hum Reprod 2005;20:191–7. 17. Fernandes S, Paracchini S, Meyer LH, Floridia G, Tyler-Smith C, Vogt PH. A large AZFc deletion removes DAZ3/DAZ4 and nearby genes from men in Y haplogroup N. Am J Hum Genet 2004;74: 180 –7. 18. Simoni M, Bakker E, Krausz C. EAA/EMQN best practice guidelines for molecular diagnosis of Y-chromosomal microdeletions. State of the art 2004. Int J Androl 2004;27:240 –9. 19. Machev N, Saut N, Longepied G, Terriou P, Navarro A, Levy N, et al. Sequence family variant loss from the AZFc interval of the human Y chromosome, but not gene copy loss, is strongly associated with male infertility. J Med Genet 2004;41:814 –25.
1063