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| BRIEF REPORT |
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| Year : 2010 | Volume : 1 | Issue : 1 | Page : 20-22 |
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PGD for a Robertsonian translocation by FISH: First successful pregnancy from India
Prochi F Madon, Arundhati S Athalye, Nandkishor J Naik, Dattatray J Naik, Firuza R Parikh
Department of Assisted Reproduction and Genetics, Jaslok Hospital and Research Centre, Mumbai-400 026, India
| Date of Web Publication |
31-Mar-2010 |
Correspondence Address:
Firuza R Parikh
Director, Department of Assisted Reproduction and Genetics, Jaslok Hospital and Research Centre, 15, Dr. G. Deshmukh Marg, Mumbai-400 026
India
DOI: 10.4103/0976-1756.62138
 Abstract |
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Preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridization (FISH) for a Robertsonian translocation was carried out in a young couple with 2 missed abortions. The wife had a karyotype of 45,XX,rob(13;14)(q10;q10). One normal embryo was obtained in the first cycle and transferred at the blastocyst stage, resulting in a successful pregnancy. This is the first reported case of PGD for a translocation from India, resulting in an ongoing pregnancy.
Keywords: Aneuploidy, balanced translocations, fluorescence in situ hybridization, preimplantation genetic diagnosis, Robertsonian
How to cite this article:
Madon PF, Athalye AS, Naik NJ, Naik DJ, Parikh FR. PGD for a Robertsonian translocation by FISH: First successful pregnancy from India. J Prenat Diagn Ther 2010;1:20-2 |
How to cite this URL:
Madon PF, Athalye AS, Naik NJ, Naik DJ, Parikh FR. PGD for a Robertsonian translocation by FISH: First successful pregnancy from India. J Prenat Diagn Ther [serial online] 2010 [cited 2013 Oct 6];1:20-2. Available from: https://jpdt.org/text.asp?2010/1/1/20/62138 |
| Introduction |
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Preimplantation genetic diagnosis (PGD) involves an additional step in ICSI, where usually one cell of each clevage stage embryo is biopsied on day-3 of the cycle and analyzed for particular genetic abnormalities. Only normal embryos are selected for transfer. PGD by the fluorescence in situ hybridization (FISH) technique is carried out in India, at the Dept. of Assisted Reproduction and Genetics of Jaslok Hospital since 2000 for detection of chromosome aneuploidies such as monosomy and trisomy. [1],[2],[3] However, PGD for detection of unbalanced translocations by FISH in cases where one of the parents is a carrier of a balanced translocation has not been reported from India earlier, though it is carried out in a few centres abroad to improve the chances of a successful pregnancy outcome. [4],[5],[6] We report the first successful case from India, where PGD was done as the wife was a carrier of a balanced Robertsonian translocation between the acrocentric chromosomes 13 and 14, resulting in an ongoing pregnancy.
Carriers of balanced translocations are phenotypically normal, hence they are generally detected only when karyotyping is done on a couple with recurrent first trimester spontaneous abortions to find its cause. Such recurrent miscarriages are often due to an unbalanced translocation in the fetus, which occurs when only one of the two chromosomes involved in the translocation is transmitted. Embryos with an unbalanced translocation can be detected by FISH during PGD, though the normal and balanced translocation embryos cannot be differentiated. Hence only the abnormal embryos with an unbalanced translocation are eliminated by PGD. Since multiple embryos are obtained during IVF, PGD gives a greater chance of finding at least one normal embryo which can be transferred, thereby increasing the chances of a normal pregnancy.
The FISH technique is used to rapidly detect specific chromosomal abnormalities even on interphase nuclei, besides metaphases. DNA probes complementary to the region of interest are labeled with different coloured fluorophores, hybridized to the test sample and analyzed through a fluorescent microscope. For PGD, multicolour FISH with a probe mixture of 5 colours (red, green, aqua, gold and blue) helps to visualize signals of 5 chromosomes simultaneously in the first round within 3-4 hours, followed by subsequent rounds on the same cell, enabling analysis of upto 12 chromosomes. [7] Proper fixation of the individual blastomeres is a critical step where the cytoplasm is removed to expose the nucleus. For PGD of translocations, probes for the chromosomes involved have to be used.
| Materials and Methods |
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A young couple married since 4 years, with a history of two missed abortions after natural conceptions visited us with a request for PGD as the wife was found to be a carrier of a balanced Robertsonian translocation with a karyotype of 45,XX,rob(13;14)(q10;q10). After genetic counseling and informed consent, PGD was carried out during the ICSI cycle. Four oocytes were retrieved, of which two fertilized and both cleaved.
A single blastomere was biopsied from each of the two embryos at the six to ten cell stage, the development of one embryo being slower than that of the other. The zona was drilled with a laser (Fertilase® , MTG Medical Technologies G.M.B.H. Germany). After hypotonic treatment the blastomeres were fixed on slides with Carnoy's fixative. After dehydration, the PGT probe (Vysis Abbott, USA) for chromosomes 13-red, 21-green, 18-aqua, X-blue and Y-gold was applied and the slide was placed on a petri plate warmer (Trivector, India) for codenaturation at 75°C for 5 minutes. Hybridization was at 37°C in a humid chamber for 3 hours. Post hybridization washing was according to the probe manufacturer's protocol and the slide was mounted in antifade. The cells were located under phase contrast and the signals viewed and captured on a Zeiss (Carl Zeiss, Germany) Axioskop-2 fluorescent microscope with Metasystems (Germany) isis software. The slides were then washed with water and the IGH-FGFR3 probe for chromosomes 14-green and 4-orange was applied for the second round of hybridization. The signals were viewed after washing and mounting in DAPI.
| Results |
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The first round of FISH on the blastomere from the well developed embryo showed two red signals for chromosome 13. Aneuploidy for chromosomes 21, 18 and sex chromosome abnormalities were ruled out, though the signals for the sex chromosomes were deleted as the sex was not revealed [Figure 1]a. The second round of FISH on the same cell showed two green signals for chromosome 14 and two orange signals for chromosome 4 [Figure 1]b, showing that this embryo was normal for the 7 chromosomes tested. This embryo had reached the blastocyst stage and was transferred. The slow growing embryo had a fragmented nucleus which was uninformative, hence a second cell was requested for biopsy, but this embryo had already arrested.
Transfer of the single normal embryo resulted in a confirmed pregnancy in the 1 st IVF cycle itself.
| Discussion |
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A few hundred children have been born worldwide after PGD for inherited translocations. This is the first successful ongoing pregnancy reported from India, after PGD for a translocation and will give hope to other childless couples with a similar history. FISH cannot differentiate if this fetus carries a balanced translocation like the mother, or has two separate copies of chromosomes 13 and 14 like the father. However, carriers of balanced translocations are generally phenotypically normal like the parent except in rare instances, which was explained to the couple during genetic counseling.
A lot of practice on arrested embryos and expertise is required in interpretation of FISH results, due to the possibility of split signals or rare signal polymorphisms which may be inherited. Hence it is advisable to test the FISH probes on blood of the couple prior to PGD. If the husband is the carrier of a balanced translocation, sperm FISH with probes of the translocated chromosomes could give an idea of the percentage of normal embryos expected.
Embryos reaching the blastocyst stage after PGD have a higher chance of being normal. [8] Genetic counseling helps the patients to make an informed decision regarding PGD. [9],[10] This is a report of a successful ongoing pregnancy for the first time in India using PGD by FISH for a translocation.
| Acknowledgements |
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The authors wish to thank the entire technical, clinical and other staff of the Department of Assisted Reproduction and Genetics for their contribution and team-work. Support from Research Grants RP 318 and RP293 of Jaslok Hospital and Research Centre, Mumbai is acknowledged.
| References |
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| 1. |
Parikh FR, Madon PF, Athalye AS, Naik NJ, Gada SD, Ganla KN, et al. Preimplantation genetic diagnosis of chromosomal abnormalities by multicolour fluorescence in situ hybridization. J Indian Med Assoc 2001;99:441-4.  |
| 2. |
Athalye AS, Madon, PF, Parikh FR. Preimplantation genetic diagnosis: Indian experience. Int J Hum Genet 2006;Suppl 2,38. |
| 3. |
Madon PF, Athalye AS, Naik NJ, Parikh FR. Pre-implantation genetic diagnosis. In: Telang M, editor. Atlas of human assisted reproductive technologies. New Delhi: Jaypee; 2007. p. 167-74. |
| 4. |
Munné S. Preimplantation genetic diagnosis for translocations. Hum Reprod 2006;21:839-40. |
| 5. |
Verlinsky Y, Tur-Kaspa I, Cieslak J, Bernal A, Morris R, Taranissi M, et al. Preimplantation testing for chromosomal disorders improves reproductive outcome of poor-prognosis patients. Reprod Biomed Online 2005;11:219-25. |
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Otani T, Roche M, Mizuike M, Colls P, Escudero T, Munné S. Preimplantation genetic diagnosis significantly improves the pregnancy outcome of translocation carriers with a history of recurrent miscarriage and unsuccessful pregnancies. Reprod Biomed Online 2006;13:869-74. |
| 7. |
Colls P, Goodall N, Zheng X, Munné S. Increased efficiency of preimplantation genetic diagnosis for aneuploidy by testing 12 chromosomes. Reprod Biomed Online 2009;19:532-8. |
| 8. |
Huang J, Lian Y, Qiao J, Chen Y, Ren X, Liu P. Characteristics of embryo development in Robertsonian translocations' preimplantation genetic diagnosis cycles. Prenat Diagn 2009: 29:1167-70. |
| 9. |
Keymolen K, Staessen C, Verpoest W, Michiels A, Bonduelle M, Haentjens P, et al. A proposal for reproductive counselling in carriers of Robertsonian translocations: 10 years of experience with preimplantation genetic diagnosis. Hum Reprod 2009;24:2365-71. |
| 10. |
Fischer J, Colls P, Escudero T, Munne S. Preimplantation genetic diagnosis (PGD) improves pregnancy outcome for translocation carriers with a history of recurrent losses. Fertil Steril 2010 (Article in press). |
[Figure 1]
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