Hum. Genet. 37,249--254 (1977) © by Springer-Verlag 1977
Original Investigations Meiotic Chromosomes in an Infertile Male with an Unbalanced Y / 1 3 Translocation Diana J. Curtis The University of Sheffield, Sub-Department of Medical Genetics, 117, Manchester Road, Sheffield S10 5DN, England
Summary. An infertile male carrying an unbalanced Y/13 translocation is described. Meiotic studies suggest that the unbalanced translocation does not affect meiotic division.
An individual with the karyotype 46,XY, der(13),t(Y;13)(q12;pll) was found during a cytogenetic survey of male subfertile patients. The mitotic and meiotic chromosome complements of this patient are described together with testicular histology, spermiogram, hormone levels and clinical history.
Clinical Description The patient, aged 26 years, has been involuntarily infertile for 4 years. He is 6 ft 1 ins tall with normal male physique, normal sexual organs, normal sexuality and there is no history of previous testicular trauma or disease. Urinary and plasma FSH and LH levels are within normal limits. The patient's family were not available for chromosome studies. The patient has one sister who is fertile and there is no history of infertility in his parents' generation.
Mitotic Karyotype Mitotic chromosomes, routinely prepared from short-term leucocyte culture, were subjected to trypsin-Leishman banding prior to analysis. Fifty metaphase plates were analysed and all metaphases showed 46 chromosomes with a normal XY complement. One chromosome 13 had prominent short arms with a strong dark band present (Fig. 1 a). The abnormal chromosome 13 did not look like a Dgroup chromosome with large satellites, other members of the D-group were strongly satellited for comparison. Metaphases stained with lacto-aceto-orcein demonstrated an abnormal chromosome (Fig. 1b), which was often difficult to distinguish from an extra C-group chromosome. Further metaphases were Cbanded with hot BaOH (Sumner, 1972); the C-banding demonstrated the hetero-
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Fig. 1 a--c. Partial mitotic karyotype of D-group and Y chromosomes, a) Trypsin-Leishman banded chromosomes, b) Lacto-aceto-orcein staining, c) C-banded chromosomes
chromatic nature of the extra material attached to the short arm of the abnormal chromosome 13 (Fig.1 c). A comparable heterochromatic region was present on the distal long arm of the normal Y chromosome. In Q-stained metaphase plates (for which photographs are unavailable due to technical limitations in the laboratory) there were two areas of intense fluorescence. One of the fluorescing areas was located on the distal long arm of the normal Y chromosome, the other was located on a D-group chromosome. The abnormal chromosome was interpreted as the distal long arm segment of a broken extra Y chromosome translocated onto a chromosome 13. The breakpoint on the extra Y chromosome appeared to be in the region Y q l 2 (Paris Conference, 1971). Evidence was not found for the survival of the major part of the extra Y chromosome.
Meiotic Karyotype A small testicular biopsy was taken from the right testis under general anaesthetic. H a l f the biopsy was processed for meiotic chromosome analysis (Evans et al., 1964; Stock et al., 1972). Diplotene plates stained with lacto-aceto-orcein were analysed as MI 23,XY or MI 24,X,Y (Fig. 2a). Twenty-five such diplotene plates studied did not show an association of the XY bivalent with any other bivalent. Subsequently slides were treated with hot B a O H and stained with Leishman.
A Y/13 Unbalanced Translocation
251
Fig. 2 a and b. Meiotic chromosomes, a) Diplotene plate stained with Leishman. b) Same diplotene plate following C-banding
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D.J. Curtis
These preparations, in which the contromeres were darkly stained, showed an abnormal D-group bivalent with a strongly stained heterochromatic short arm area (Fig. 2b). This was interpreted as the distal area of the broken and translocated extra Y chromosome.
Histology and Spermiogenesis Half of the testis biopsy was processed for routine histology. The sample showed normal tube diameter and there was no evidence of fibrosis or hyalinisation. Spermatogenesis proceeded through to sperm-head stage in a number of tubes (Fig. 3). There was a general reduction in the number of spermatogonial cells present in the germinal epithelium and a reduction in the frequency of sperm-
Fig. 3. T.S. Testis. Haematoxylin-Eosin stain. A: Primary spermatocyte. B: Secondary spermatocyte. C: Sperm-head stage
Table 1. Sperm characteristics Of the patient, determined on two occasions separated bY a 3-months interval Vol. ml
Count × 106/ml
% Motility Maturation
4.7 4.0
9 3
30 40
Normal Normal
A Y/13 Unbalanced Translocation
253
head stages seen. The sample was classified as general maturation arrest. A testicular biopsy score count (Johnsen, 1970) gave a score of 8.3. The mean score for normal testis is 9.38 +0.24. Sperm counts were made on two occasions separated by a 3-month interval (Table 1). The patient was classified as severe oligospermic with reduced sperm motility.
Discussion A number of Y/autosome translocations were described prior to the introduction of banding techniques. However, without the aid of C- or Q-banding to identify the presence of Y chromosome material, these cases remain equivocal. Recent banded chromosome identifications of Y/autosome translocations fall into two groups. There are those identified through Y fluorescent screening programmes (Frtind et al., 1972; Lundsteen and Phillips, 1973) and those through the patients' infertility (Noel et al., 1971; Chandley et al., 1975) which include the present case. All these Y/autosome translocations involved translocations onto acrocentric autosomes. All result from similar break-points on the Y chromosomes preserving the distal brilliantly fluorescing segment of the extra Y chromosome. In two cases (Chandley et al., 1975; Lundsteen and Phillips, 1973) the translocation was onto a chromosome 22. In the other two cases the translocation was onto a chromosome 15. The present case describes an extra broken Y translocated onto a chromosome 13. Meiotic studies in the present case confirmed the karyotype. All the diplotene plates studied showed that the abnormal bivalent 13 carrying the translocation was never involved with the normal XY bivalent. Metaphase II plates were frequent in preparations from this patient. Analysis of meiotic stages therefore strongly suggests that the unbalanced translocation present in this case does not hinder the segregation of bivalents during meiosis. The lack of intimate pairing of the Y chromosome during meiosis in fact presupposes that the presence of extra Y material, wherever it is located, will not affect segregation. Thus in the present case the primary cause of the patient's infertility cannot be related to the presence of extra chromosome material in his karyotype. Evidence from population studies (Chandley et al., 1975) suggests that the frequency of male subfertile individuals carrying extra Y chromosome material is not significantly different from the frequency of individuals carrying extra Y chromosome material in the general population.
Acknowledgement. This work forms part of a larger study into causes of male infertility and was funded by a grant to Professor I. D. Cooke, Professor of Obstetrics and Gynaecology at the Jessop Hospital for Women, Sheffield. I am grateful to Professor I. D. Cooke and Mr. L. L. Williams, Consultant Urologist at the Royal Hospital, Sheffield, for permission to describe the cytogenetics of this patient. Dr. A. Thomas, Clinical Research Assistant, obtained and kept the clinical records.
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D.J. Curtis
References Chandley, A. C., Edmond, P., Christie, S., Gowans, L., Fletcher, V., Frackiewicz, A., Newton, M.: Cytogenetics and infertility in man. Ann. hum. Genet. 39, 231--252 (1975) Evans, E. P., Breckon, G., Ford, C. E.: An air-drying method for meiotic preparations from mammalian testes. Cytogenetics 3, 289--294 (1964) Frtind, S., Koske-Westphal, T., Fuchs-Mecke, S., Passarge, E.: Quinacrine mustard fluorescence of a second Y chromosome in a Y-autosomal translocation. Humangenetik 14, 133--136 (1972) Johnsen, S. G.: Testicular biopsy score count. A method for registration of spermatogenesis in human testes. Normal values and results in 335 hypogonadal males. Hormones 1, 2--25 (1970) Lundsteen, C., Phillips, J.: Y/22 translocation in a YY male. Cytogenet. Cell Genet.12, 53--59 (1973) Noel, B., Emerit, I., Luciani, J. M., Quack, B.: A familial Y/autosome translocation in man. Clin. Genet. 2, 1--6 (1971) Paris Conference 1971: Standardization in human genetics. Birth defects: Original article series, vol. 8, No. 7. The National Foundation, NY 1972 Stock, A. D., Burnham, D. B., Hsu, T. D.: Giemsa banding of meiotic chromosomes with description of a procedure for cytological preparations from solid tissues. Cytogenetics 11, 534--539 (1972) Sumner, A. T.: A simple technique for demonstrating centromeric heterochromatin. Exp. Cell Res. 75, 304--306 (1972)
Received March 3, 1977
Original Investigations Meiotic Chromosomes in an Infertile Male with an Unbalanced Y / 1 3 Translocation Diana J. Curtis The University of Sheffield, Sub-Department of Medical Genetics, 117, Manchester Road, Sheffield S10 5DN, England
Summary. An infertile male carrying an unbalanced Y/13 translocation is described. Meiotic studies suggest that the unbalanced translocation does not affect meiotic division.
An individual with the karyotype 46,XY, der(13),t(Y;13)(q12;pll) was found during a cytogenetic survey of male subfertile patients. The mitotic and meiotic chromosome complements of this patient are described together with testicular histology, spermiogram, hormone levels and clinical history.
Clinical Description The patient, aged 26 years, has been involuntarily infertile for 4 years. He is 6 ft 1 ins tall with normal male physique, normal sexual organs, normal sexuality and there is no history of previous testicular trauma or disease. Urinary and plasma FSH and LH levels are within normal limits. The patient's family were not available for chromosome studies. The patient has one sister who is fertile and there is no history of infertility in his parents' generation.
Mitotic Karyotype Mitotic chromosomes, routinely prepared from short-term leucocyte culture, were subjected to trypsin-Leishman banding prior to analysis. Fifty metaphase plates were analysed and all metaphases showed 46 chromosomes with a normal XY complement. One chromosome 13 had prominent short arms with a strong dark band present (Fig. 1 a). The abnormal chromosome 13 did not look like a Dgroup chromosome with large satellites, other members of the D-group were strongly satellited for comparison. Metaphases stained with lacto-aceto-orcein demonstrated an abnormal chromosome (Fig. 1b), which was often difficult to distinguish from an extra C-group chromosome. Further metaphases were Cbanded with hot BaOH (Sumner, 1972); the C-banding demonstrated the hetero-
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D.J. Curtis
Fig. 1 a--c. Partial mitotic karyotype of D-group and Y chromosomes, a) Trypsin-Leishman banded chromosomes, b) Lacto-aceto-orcein staining, c) C-banded chromosomes
chromatic nature of the extra material attached to the short arm of the abnormal chromosome 13 (Fig.1 c). A comparable heterochromatic region was present on the distal long arm of the normal Y chromosome. In Q-stained metaphase plates (for which photographs are unavailable due to technical limitations in the laboratory) there were two areas of intense fluorescence. One of the fluorescing areas was located on the distal long arm of the normal Y chromosome, the other was located on a D-group chromosome. The abnormal chromosome was interpreted as the distal long arm segment of a broken extra Y chromosome translocated onto a chromosome 13. The breakpoint on the extra Y chromosome appeared to be in the region Y q l 2 (Paris Conference, 1971). Evidence was not found for the survival of the major part of the extra Y chromosome.
Meiotic Karyotype A small testicular biopsy was taken from the right testis under general anaesthetic. H a l f the biopsy was processed for meiotic chromosome analysis (Evans et al., 1964; Stock et al., 1972). Diplotene plates stained with lacto-aceto-orcein were analysed as MI 23,XY or MI 24,X,Y (Fig. 2a). Twenty-five such diplotene plates studied did not show an association of the XY bivalent with any other bivalent. Subsequently slides were treated with hot B a O H and stained with Leishman.
A Y/13 Unbalanced Translocation
251
Fig. 2 a and b. Meiotic chromosomes, a) Diplotene plate stained with Leishman. b) Same diplotene plate following C-banding
252
D.J. Curtis
These preparations, in which the contromeres were darkly stained, showed an abnormal D-group bivalent with a strongly stained heterochromatic short arm area (Fig. 2b). This was interpreted as the distal area of the broken and translocated extra Y chromosome.
Histology and Spermiogenesis Half of the testis biopsy was processed for routine histology. The sample showed normal tube diameter and there was no evidence of fibrosis or hyalinisation. Spermatogenesis proceeded through to sperm-head stage in a number of tubes (Fig. 3). There was a general reduction in the number of spermatogonial cells present in the germinal epithelium and a reduction in the frequency of sperm-
Fig. 3. T.S. Testis. Haematoxylin-Eosin stain. A: Primary spermatocyte. B: Secondary spermatocyte. C: Sperm-head stage
Table 1. Sperm characteristics Of the patient, determined on two occasions separated bY a 3-months interval Vol. ml
Count × 106/ml
% Motility Maturation
4.7 4.0
9 3
30 40
Normal Normal
A Y/13 Unbalanced Translocation
253
head stages seen. The sample was classified as general maturation arrest. A testicular biopsy score count (Johnsen, 1970) gave a score of 8.3. The mean score for normal testis is 9.38 +0.24. Sperm counts were made on two occasions separated by a 3-month interval (Table 1). The patient was classified as severe oligospermic with reduced sperm motility.
Discussion A number of Y/autosome translocations were described prior to the introduction of banding techniques. However, without the aid of C- or Q-banding to identify the presence of Y chromosome material, these cases remain equivocal. Recent banded chromosome identifications of Y/autosome translocations fall into two groups. There are those identified through Y fluorescent screening programmes (Frtind et al., 1972; Lundsteen and Phillips, 1973) and those through the patients' infertility (Noel et al., 1971; Chandley et al., 1975) which include the present case. All these Y/autosome translocations involved translocations onto acrocentric autosomes. All result from similar break-points on the Y chromosomes preserving the distal brilliantly fluorescing segment of the extra Y chromosome. In two cases (Chandley et al., 1975; Lundsteen and Phillips, 1973) the translocation was onto a chromosome 22. In the other two cases the translocation was onto a chromosome 15. The present case describes an extra broken Y translocated onto a chromosome 13. Meiotic studies in the present case confirmed the karyotype. All the diplotene plates studied showed that the abnormal bivalent 13 carrying the translocation was never involved with the normal XY bivalent. Metaphase II plates were frequent in preparations from this patient. Analysis of meiotic stages therefore strongly suggests that the unbalanced translocation present in this case does not hinder the segregation of bivalents during meiosis. The lack of intimate pairing of the Y chromosome during meiosis in fact presupposes that the presence of extra Y material, wherever it is located, will not affect segregation. Thus in the present case the primary cause of the patient's infertility cannot be related to the presence of extra chromosome material in his karyotype. Evidence from population studies (Chandley et al., 1975) suggests that the frequency of male subfertile individuals carrying extra Y chromosome material is not significantly different from the frequency of individuals carrying extra Y chromosome material in the general population.
Acknowledgement. This work forms part of a larger study into causes of male infertility and was funded by a grant to Professor I. D. Cooke, Professor of Obstetrics and Gynaecology at the Jessop Hospital for Women, Sheffield. I am grateful to Professor I. D. Cooke and Mr. L. L. Williams, Consultant Urologist at the Royal Hospital, Sheffield, for permission to describe the cytogenetics of this patient. Dr. A. Thomas, Clinical Research Assistant, obtained and kept the clinical records.
254
D.J. Curtis
References Chandley, A. C., Edmond, P., Christie, S., Gowans, L., Fletcher, V., Frackiewicz, A., Newton, M.: Cytogenetics and infertility in man. Ann. hum. Genet. 39, 231--252 (1975) Evans, E. P., Breckon, G., Ford, C. E.: An air-drying method for meiotic preparations from mammalian testes. Cytogenetics 3, 289--294 (1964) Frtind, S., Koske-Westphal, T., Fuchs-Mecke, S., Passarge, E.: Quinacrine mustard fluorescence of a second Y chromosome in a Y-autosomal translocation. Humangenetik 14, 133--136 (1972) Johnsen, S. G.: Testicular biopsy score count. A method for registration of spermatogenesis in human testes. Normal values and results in 335 hypogonadal males. Hormones 1, 2--25 (1970) Lundsteen, C., Phillips, J.: Y/22 translocation in a YY male. Cytogenet. Cell Genet.12, 53--59 (1973) Noel, B., Emerit, I., Luciani, J. M., Quack, B.: A familial Y/autosome translocation in man. Clin. Genet. 2, 1--6 (1971) Paris Conference 1971: Standardization in human genetics. Birth defects: Original article series, vol. 8, No. 7. The National Foundation, NY 1972 Stock, A. D., Burnham, D. B., Hsu, T. D.: Giemsa banding of meiotic chromosomes with description of a procedure for cytological preparations from solid tissues. Cytogenetics 11, 534--539 (1972) Sumner, A. T.: A simple technique for demonstrating centromeric heterochromatin. Exp. Cell Res. 75, 304--306 (1972)
Received March 3, 1977
