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Heterogeneity in recurrent complete hydatidiform mole: Presentation of two new Turkish families with different genetic characteristics
Placenta 31 (2010) 1023e1025
Contents lists available at ScienceDirect
Placenta journal homepage: www.elsevier.com/locate/placenta
Case Report
Heterogeneity in recurrent complete hydatidiform mole: Presentation of two new Turkish families with different genetic characteristics S. Buyukkurt a, *, R.A. Fisher b, M.A. Vardar a, C. Evruke a a b
University of Cukurova School of Medicine, Department of Obstetrics & Gynecology, 01330 Adana, Turkey Institute of Reproductive and Developmental Biology, Imperial College London, London, W12 0NN, UK
a r t i c l e i n f o
a b s t r a c t
Article history: Accepted 2 September 2010
Subsequent pregnancy outcomes following complete hydatidiform moles (CHM) are usually favorable and the risk of a second CHM less than 2%. However, a small number of women have a rare autosomal recessive condition that predisposes them to CHM. Unlike typical CHM, that are androgenetic (AnCHM), the CHM in these women are diploid and biparental (BiCHM) with a contribution from each parent to the nuclear genome. To date most women with recurrent CHM have been found to have BiCHM and to have a wide variety of mutations in the causative gene, NLRP7. Our objectives were to genotype the molar tissue and identify the NLRP7 mutations in two unrelated Turkish women with recurrent CHM. Fluorescent microsatellite genotyping of molar tissue and screening of patient DNA for NLRP7 mutations was carried out in two women with five and four CHM respectively. The first case was confirmed to have BiCHM. In addition the patient was found to have a novel homozygous mutation in exon 8 of NLRP7. All CHM examined in the second case were AnCHM and no NLRP7 mutations were identified in DNA from the patient. This report describes a further individual with BiCHM and a novel mutation in NLRP7. A second patient with similar clinical history had no mutations in NLRP7 and is the first report of a patient with four CHM where the CHM are androgenetic. This study highlights the heterogeneity of recurrent CHM and the need to investigate women with recurrent molar pregnancies for appropriate clinical management. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Recurrent hydatidiform mole Familial hydatidiform mole Biparental complete mole NLRP7 Genomic imprinting
1. Introduction Hydatidiform mole (HM) is an abnormal pregnancy with over proliferation of the placenta while the embryonic development is severely abnormal or absent. In general partial HM (PHM) results from the fertilization of an ovum by two sperm while most complete HM (CHM) are sporadic and are androgenetic (AnCHM) having two sets of paternal chromosomes. The paternal contribution may be monospermic (approximately 80%) or dispermic (approximately 20%) [1]. Rarely CHM are diploid with both a maternal and paternal chromosome complement (BiCHM). These BiCHM are associated with an autosomal recessive condition in which affected women have recurrent HM (RHM). In 2006 NLRP7, located on chromosome 19q13.4, was shown to be the causative gene for these BiCHM [2]. Our objective was to perform genotyping of molar tissue and NLRP7 screening in two unrelated Turkish women with five and four RHM * Corresponding author. Çukurova Üniversitesi Tıp Fakültesi Kadın Hastalıkları ve um Anabilim Dalı, 01330 Adana, Turkey. Tel.: þ 90 322 3443252. Dog E-mail addresses: [email protected] (S. Buyukkurt), r.fisher@imperial. ac.uk (R.A. Fisher), [email protected] (M.A. Vardar), [email protected] (C. Evruke). 0143-4004/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.placenta.2010.09.003
respectively in order to compare the mutations found in these women with those previously reported. 2. Cases Case 1 is a 35-year old woman with a total of five pregnancies in the previous seven years, all of which were diagnosed as CHM. Tissue from the last molar pregnancy was available for genetic analysis. Case 2 is a 24-year old woman who has had four pregnancies in four years. The first pregnancy was diagnosed as CHM, but was treated elsewhere and pathological material was not available for review. Tissue from the three subsequent molar pregnancies was available for review and genetic analysis. There is no consanguinity or history of infertility in either family. Both the patients and their partners have normal karyoptypes. 2.1. Fluorescent microsatellite genotyping of complete hydatidiform moles Genotypes of parental and molar DNA for the two cases are shown in Table 1. In case 1 DNA from the molar tissue was found to
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S. Buyukkurt et al. / Placenta 31 (2010) 1023e1025
Table 1 Informative microsatellite polymorphisms in case 1 and 2. Microsatellite marker
Allele size in base pairs in case 1 Mother
CHM5
Father
D1S1656 D9S43 D12S391 D13S317 D15S659 D17S122
128e136 82e86 224e227 174 168e184 164
128e148 82e84 220e224 174e186 168e196 160e164
148 84e90 216e220 186e190 196 160e162
Allele size in base pairs in case 2
D3S1262 D7S669 D9S171 D12S391 D13S317 D14S306 D20S481 D22S264 DXS451 AMELX/Y
Mother
CHM2
CHM3
CHM4
Father
103e108 118 164e174 220 182e190 195e207 231e239 195e202 174e193 104
114 124 157 216 174 191 243 200 186 104
105 132 170 228 174 191 247 200 186 104
105 132 157 216 194 203 247 200 186 104
105e114 124e132 157e170 216e228 174e194 191e203 243e247 200 186 104e110
be heterozygous for six informative markers with a contribution from both parents. The relative proportion of the two alleles was consistent with a single contribution from each parent with no evidence of trisomy for any of the markers examined. The molar tissue in this case was confirmed as a BiCHM. All three hydatidiform moles examined in case 2 were found to have only a single allele for all informative markers tested. For the eight autosomal markers this allele was found only in the paternal DNA. No maternal contribution to the nuclear DNA was found for the autosomal markers. All three CHM were female, having only X (104 base pairs) alleles for the sex chromosome specific marker, AMELX/Y. For the X chromosome marker DXS451 the CHM have only the paternally derived 186 base pair allele confirming that the X chromosomes are also inherited from the father and that all three CHM are typical AnCHM. While the paternal DNA is heterozygous for 8 of the markers examined, the CHM are homozygous, consistent with a monospermic origin for all three CHM. 2.2. Mutation screening of NLRP7 Sequencing of the exonic regions of NLRP7 in case 1 revealed the patient to be homozygous for an insertion in exon 8, c.2571_2572insC (Fig. 1), resulting in a premature stop codon and truncated protein, pI858HfsX11. In case 2 no NLRP7 mutations were identified in DNA from the patient. 3. Discussion Subsequent pregnancy outcomes following CHM are usually favorable, except in a small group of women with an autosomal condition that predisposes to CHM [3]. The risk of a subsequent HM following a CHM is approximately 1.9%. Eighty per cent of these will be followed by a further CHM and 20% a PHM [4]. Since BiCHM are rare, most of the these CHM will have been AnCHM. The risk of greater than two AnCHM is likely to be low as we are aware of only two previous individuals with more than two AnCHM [5]. However, for women with an inherited predisposition to molar pregnancies who have BiCHM the risk of a further CHM is 75% and other reproductive wastage common [6,7]. Since affected women are unlikely to have a normal pregnancy and risk persistent
Fig. 1. Partial sequencing electropherogram showing the novel mutation in NLRP7. The upper panel represents wild type sequence from a normal control. The lower panel represents partial sequence from case 1 showing a homozygous insertion of a cytosine base (arrow) resulting in a premature stop codon (dotted arrow).
trophoblastic disease following each molar pregnancy, it is important to determine whether women with RHM have an inherited predisposition to these pregnancies. In this report we have screened two Turkish women with no family history of molar pregnancies whose only pregnancies were CHM, one woman having five and the other four CHM. Despite the very similar clinical presentation and the expectation that both women would have BiCHM, only case 1 was shown to have BiCHM. All three molar pregnancies tested in the second case were shown to be AnCHM of monospermic origin. To our knowledge this is the first reported case of a women with four CHM of androgenetic, rather than biparental, origin. While the function of NLRP7 in pregnancy has yet to be elucidated, mutations have been reported in over 50 families with BiCHM and include deletions, insertions, duplications and amino acid substitutions [2,7e9]. Mutations giving rise to truncated proteins are distributed throughout the gene while those resulting in amino acid substitutions appear to be clustered in the leucine rich region [7]. Two Turkish families with familial BiCHM have previously been reported to carry the same mutation, pR693 W, and to share haplotypes across the 19q13.4 region [7]. Neither of the women in the present study carried this mutation. Instead, screening of the coding sequences of NLRP7 in case 1, identified a novel homozygous insertion, the first mutation to be described in exon 8. AnCHM arise by a very different mechanism involving a conception in which the nuclear genome is effectively lost or inactivated and both sets of chromosomes are paternal in origin. It has been proposed that AnCHM arise by fertilization of an anucleate ovum by a single sperm that then duplicates or fertilization of an anucleate ovum by two sperms. Without evidence for anucleate eggs an alternative mechanism for CHM, postzygotic diploidisation of a triploid conceptus, has been suggested [10]. Mutations in NLRP7 do not appear to be associated with AnCHM. However, it is possible that another gene, predisposing to anucleate ova or triploid conceptuses, might be involved in RHM of androgenetic origin. The effect of this gene is likely to be small given the rarity of women with more than two AnCHM. The observation that CHM in case 2 are of androgenetic origin has important implications for patient management. Women with BiCHM are unlikely to have a successful pregnancy and each successive molar pregnancy carries a risk of persistent trophoblastic disease similar to that for an AnCHM [6]. Only a single family
S. Buyukkurt et al. / Placenta 31 (2010) 1023e1025
in the literature with BiCHM has achieved normal pregnancies [3]. This may be associated with a specific mutation in this family that has not been reported in any other families to date [2]. However, women with recurrent AnCHM can achieve a normal pregnancy naturally [5]. In addition a number of reproductive strategies are available to prevent further molar pregnancies in these women. However, these techniques are not appropriate for women with recurrent BiCHM. This study highlights the need to perform genetic analysis on molar tissue in women with RHM, particularly where there is no family history of molar pregnancies and the inherited nature of the condition is unclear. Although at present there is no proven strategy for preventing further molar pregnancies in women with BiCHM, women with AnCHM can expect to achieve a normal pregnancy and it is therefore clinically important to differentiate these women. As emphasised in this report a diagnosis of BiCHM cannot be made on the basis of clinical history or pathology and we therefore recommend that genotyping of molar tissue is performed for women who have RHM in the absence of normal pregnancies.
Acknowledgements This work was supported by a grants from the Cancer Treatment and Research Trust.
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References [1] Fisher RA, Povey S, Jeffreys AJ, Martin CA, Patel I, Lawler SD. Frequency of heterozygous complete hydatidiform moles, estimated by locus-specific minisatellite and Y chromosome-specific probes. Hum Genet 1989;82:259e63. [2] Murdoch S, Djuric U, Mazhar B, Seoud M, Khan R, Kuick R, et al. Mutations in NALP7 cause recurrent hydatidiform moles and reproductive wastage in humans. Nat Genet 2006;38:300e2. [3] Helwani MN, Seoud M, Zahed L, Zaatari G, Khalil A, Slim R. A familial case of recurrent hydatidiform molar pregnancies with biparental genomic contribution. Hum Genet 1999;105:112e5. [4] Sebire NJ, Fisher RA, Foskett M, Rees H, Seckl MJ, Newlands ES. Risk of recurrent hydatidiform mole and subsequent pregnancy outcome following complete or partial hydatidiform molar pregnancy. BJOG 2003;110:22e6. [5] van der Smagt JJ, Scheenjes E, Kremer JA, Hennekam FA, Fisher RA. Heterogeneity in the origin of recurrent complete hydatidiform moles: not all women with multiple molar pregnancies have biparental moles. BJOG 2006;113:725e8. [6] Fisher RA, Hodges MD, Newlands ES. Familial recurrent hydatidiform mole: a review. J Reprod Med 2004;49:595e601. [7] Wang CM, Dixon PH, Decordova S, Hodges MD, Sebire NJ, Ozalp S, et al. Identification of 13 novel NLRP7 mutations in 20 families with recurrent hydatidiform mole; missense mutations cluster in the leucine-rich region. J Med Genet 2009;46:569e75. [8] Kou YC, Shao L, Peng HH, Rosetta R, del Gaudio D, Wagner AF, et al. A recurrent intragenic genomic duplication, other novel mutations in NLRP7 and imprinting defects in recurrent biparental hydatidiform moles. Mol Hum Reprod 2008;14:33e40. [9] Hayward BE, De Vos M, Talati N, Abdollahi MR, Taylor GR, Meyer E, et al. Genetic and epigenetic analysis of recurrent hydatidiform mole. Hum Mutat 2009;30:E629e39. [10] Golubovsky MD. Postzygotic diploidization of triploids as a source of unusual cases of mosaicism, chimerism and twinning. Hum Reprod 2003;18:236e42.
Contents lists available at ScienceDirect
Placenta journal homepage: www.elsevier.com/locate/placenta
Case Report
Heterogeneity in recurrent complete hydatidiform mole: Presentation of two new Turkish families with different genetic characteristics S. Buyukkurt a, *, R.A. Fisher b, M.A. Vardar a, C. Evruke a a b
University of Cukurova School of Medicine, Department of Obstetrics & Gynecology, 01330 Adana, Turkey Institute of Reproductive and Developmental Biology, Imperial College London, London, W12 0NN, UK
a r t i c l e i n f o
a b s t r a c t
Article history: Accepted 2 September 2010
Subsequent pregnancy outcomes following complete hydatidiform moles (CHM) are usually favorable and the risk of a second CHM less than 2%. However, a small number of women have a rare autosomal recessive condition that predisposes them to CHM. Unlike typical CHM, that are androgenetic (AnCHM), the CHM in these women are diploid and biparental (BiCHM) with a contribution from each parent to the nuclear genome. To date most women with recurrent CHM have been found to have BiCHM and to have a wide variety of mutations in the causative gene, NLRP7. Our objectives were to genotype the molar tissue and identify the NLRP7 mutations in two unrelated Turkish women with recurrent CHM. Fluorescent microsatellite genotyping of molar tissue and screening of patient DNA for NLRP7 mutations was carried out in two women with five and four CHM respectively. The first case was confirmed to have BiCHM. In addition the patient was found to have a novel homozygous mutation in exon 8 of NLRP7. All CHM examined in the second case were AnCHM and no NLRP7 mutations were identified in DNA from the patient. This report describes a further individual with BiCHM and a novel mutation in NLRP7. A second patient with similar clinical history had no mutations in NLRP7 and is the first report of a patient with four CHM where the CHM are androgenetic. This study highlights the heterogeneity of recurrent CHM and the need to investigate women with recurrent molar pregnancies for appropriate clinical management. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Recurrent hydatidiform mole Familial hydatidiform mole Biparental complete mole NLRP7 Genomic imprinting
1. Introduction Hydatidiform mole (HM) is an abnormal pregnancy with over proliferation of the placenta while the embryonic development is severely abnormal or absent. In general partial HM (PHM) results from the fertilization of an ovum by two sperm while most complete HM (CHM) are sporadic and are androgenetic (AnCHM) having two sets of paternal chromosomes. The paternal contribution may be monospermic (approximately 80%) or dispermic (approximately 20%) [1]. Rarely CHM are diploid with both a maternal and paternal chromosome complement (BiCHM). These BiCHM are associated with an autosomal recessive condition in which affected women have recurrent HM (RHM). In 2006 NLRP7, located on chromosome 19q13.4, was shown to be the causative gene for these BiCHM [2]. Our objective was to perform genotyping of molar tissue and NLRP7 screening in two unrelated Turkish women with five and four RHM * Corresponding author. Çukurova Üniversitesi Tıp Fakültesi Kadın Hastalıkları ve um Anabilim Dalı, 01330 Adana, Turkey. Tel.: þ 90 322 3443252. Dog E-mail addresses: [email protected] (S. Buyukkurt), r.fisher@imperial. ac.uk (R.A. Fisher), [email protected] (M.A. Vardar), [email protected] (C. Evruke). 0143-4004/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.placenta.2010.09.003
respectively in order to compare the mutations found in these women with those previously reported. 2. Cases Case 1 is a 35-year old woman with a total of five pregnancies in the previous seven years, all of which were diagnosed as CHM. Tissue from the last molar pregnancy was available for genetic analysis. Case 2 is a 24-year old woman who has had four pregnancies in four years. The first pregnancy was diagnosed as CHM, but was treated elsewhere and pathological material was not available for review. Tissue from the three subsequent molar pregnancies was available for review and genetic analysis. There is no consanguinity or history of infertility in either family. Both the patients and their partners have normal karyoptypes. 2.1. Fluorescent microsatellite genotyping of complete hydatidiform moles Genotypes of parental and molar DNA for the two cases are shown in Table 1. In case 1 DNA from the molar tissue was found to
1024
S. Buyukkurt et al. / Placenta 31 (2010) 1023e1025
Table 1 Informative microsatellite polymorphisms in case 1 and 2. Microsatellite marker
Allele size in base pairs in case 1 Mother
CHM5
Father
D1S1656 D9S43 D12S391 D13S317 D15S659 D17S122
128e136 82e86 224e227 174 168e184 164
128e148 82e84 220e224 174e186 168e196 160e164
148 84e90 216e220 186e190 196 160e162
Allele size in base pairs in case 2
D3S1262 D7S669 D9S171 D12S391 D13S317 D14S306 D20S481 D22S264 DXS451 AMELX/Y
Mother
CHM2
CHM3
CHM4
Father
103e108 118 164e174 220 182e190 195e207 231e239 195e202 174e193 104
114 124 157 216 174 191 243 200 186 104
105 132 170 228 174 191 247 200 186 104
105 132 157 216 194 203 247 200 186 104
105e114 124e132 157e170 216e228 174e194 191e203 243e247 200 186 104e110
be heterozygous for six informative markers with a contribution from both parents. The relative proportion of the two alleles was consistent with a single contribution from each parent with no evidence of trisomy for any of the markers examined. The molar tissue in this case was confirmed as a BiCHM. All three hydatidiform moles examined in case 2 were found to have only a single allele for all informative markers tested. For the eight autosomal markers this allele was found only in the paternal DNA. No maternal contribution to the nuclear DNA was found for the autosomal markers. All three CHM were female, having only X (104 base pairs) alleles for the sex chromosome specific marker, AMELX/Y. For the X chromosome marker DXS451 the CHM have only the paternally derived 186 base pair allele confirming that the X chromosomes are also inherited from the father and that all three CHM are typical AnCHM. While the paternal DNA is heterozygous for 8 of the markers examined, the CHM are homozygous, consistent with a monospermic origin for all three CHM. 2.2. Mutation screening of NLRP7 Sequencing of the exonic regions of NLRP7 in case 1 revealed the patient to be homozygous for an insertion in exon 8, c.2571_2572insC (Fig. 1), resulting in a premature stop codon and truncated protein, pI858HfsX11. In case 2 no NLRP7 mutations were identified in DNA from the patient. 3. Discussion Subsequent pregnancy outcomes following CHM are usually favorable, except in a small group of women with an autosomal condition that predisposes to CHM [3]. The risk of a subsequent HM following a CHM is approximately 1.9%. Eighty per cent of these will be followed by a further CHM and 20% a PHM [4]. Since BiCHM are rare, most of the these CHM will have been AnCHM. The risk of greater than two AnCHM is likely to be low as we are aware of only two previous individuals with more than two AnCHM [5]. However, for women with an inherited predisposition to molar pregnancies who have BiCHM the risk of a further CHM is 75% and other reproductive wastage common [6,7]. Since affected women are unlikely to have a normal pregnancy and risk persistent
Fig. 1. Partial sequencing electropherogram showing the novel mutation in NLRP7. The upper panel represents wild type sequence from a normal control. The lower panel represents partial sequence from case 1 showing a homozygous insertion of a cytosine base (arrow) resulting in a premature stop codon (dotted arrow).
trophoblastic disease following each molar pregnancy, it is important to determine whether women with RHM have an inherited predisposition to these pregnancies. In this report we have screened two Turkish women with no family history of molar pregnancies whose only pregnancies were CHM, one woman having five and the other four CHM. Despite the very similar clinical presentation and the expectation that both women would have BiCHM, only case 1 was shown to have BiCHM. All three molar pregnancies tested in the second case were shown to be AnCHM of monospermic origin. To our knowledge this is the first reported case of a women with four CHM of androgenetic, rather than biparental, origin. While the function of NLRP7 in pregnancy has yet to be elucidated, mutations have been reported in over 50 families with BiCHM and include deletions, insertions, duplications and amino acid substitutions [2,7e9]. Mutations giving rise to truncated proteins are distributed throughout the gene while those resulting in amino acid substitutions appear to be clustered in the leucine rich region [7]. Two Turkish families with familial BiCHM have previously been reported to carry the same mutation, pR693 W, and to share haplotypes across the 19q13.4 region [7]. Neither of the women in the present study carried this mutation. Instead, screening of the coding sequences of NLRP7 in case 1, identified a novel homozygous insertion, the first mutation to be described in exon 8. AnCHM arise by a very different mechanism involving a conception in which the nuclear genome is effectively lost or inactivated and both sets of chromosomes are paternal in origin. It has been proposed that AnCHM arise by fertilization of an anucleate ovum by a single sperm that then duplicates or fertilization of an anucleate ovum by two sperms. Without evidence for anucleate eggs an alternative mechanism for CHM, postzygotic diploidisation of a triploid conceptus, has been suggested [10]. Mutations in NLRP7 do not appear to be associated with AnCHM. However, it is possible that another gene, predisposing to anucleate ova or triploid conceptuses, might be involved in RHM of androgenetic origin. The effect of this gene is likely to be small given the rarity of women with more than two AnCHM. The observation that CHM in case 2 are of androgenetic origin has important implications for patient management. Women with BiCHM are unlikely to have a successful pregnancy and each successive molar pregnancy carries a risk of persistent trophoblastic disease similar to that for an AnCHM [6]. Only a single family
S. Buyukkurt et al. / Placenta 31 (2010) 1023e1025
in the literature with BiCHM has achieved normal pregnancies [3]. This may be associated with a specific mutation in this family that has not been reported in any other families to date [2]. However, women with recurrent AnCHM can achieve a normal pregnancy naturally [5]. In addition a number of reproductive strategies are available to prevent further molar pregnancies in these women. However, these techniques are not appropriate for women with recurrent BiCHM. This study highlights the need to perform genetic analysis on molar tissue in women with RHM, particularly where there is no family history of molar pregnancies and the inherited nature of the condition is unclear. Although at present there is no proven strategy for preventing further molar pregnancies in women with BiCHM, women with AnCHM can expect to achieve a normal pregnancy and it is therefore clinically important to differentiate these women. As emphasised in this report a diagnosis of BiCHM cannot be made on the basis of clinical history or pathology and we therefore recommend that genotyping of molar tissue is performed for women who have RHM in the absence of normal pregnancies.
Acknowledgements This work was supported by a grants from the Cancer Treatment and Research Trust.
1025
References [1] Fisher RA, Povey S, Jeffreys AJ, Martin CA, Patel I, Lawler SD. Frequency of heterozygous complete hydatidiform moles, estimated by locus-specific minisatellite and Y chromosome-specific probes. Hum Genet 1989;82:259e63. [2] Murdoch S, Djuric U, Mazhar B, Seoud M, Khan R, Kuick R, et al. Mutations in NALP7 cause recurrent hydatidiform moles and reproductive wastage in humans. Nat Genet 2006;38:300e2. [3] Helwani MN, Seoud M, Zahed L, Zaatari G, Khalil A, Slim R. A familial case of recurrent hydatidiform molar pregnancies with biparental genomic contribution. Hum Genet 1999;105:112e5. [4] Sebire NJ, Fisher RA, Foskett M, Rees H, Seckl MJ, Newlands ES. Risk of recurrent hydatidiform mole and subsequent pregnancy outcome following complete or partial hydatidiform molar pregnancy. BJOG 2003;110:22e6. [5] van der Smagt JJ, Scheenjes E, Kremer JA, Hennekam FA, Fisher RA. Heterogeneity in the origin of recurrent complete hydatidiform moles: not all women with multiple molar pregnancies have biparental moles. BJOG 2006;113:725e8. [6] Fisher RA, Hodges MD, Newlands ES. Familial recurrent hydatidiform mole: a review. J Reprod Med 2004;49:595e601. [7] Wang CM, Dixon PH, Decordova S, Hodges MD, Sebire NJ, Ozalp S, et al. Identification of 13 novel NLRP7 mutations in 20 families with recurrent hydatidiform mole; missense mutations cluster in the leucine-rich region. J Med Genet 2009;46:569e75. [8] Kou YC, Shao L, Peng HH, Rosetta R, del Gaudio D, Wagner AF, et al. A recurrent intragenic genomic duplication, other novel mutations in NLRP7 and imprinting defects in recurrent biparental hydatidiform moles. Mol Hum Reprod 2008;14:33e40. [9] Hayward BE, De Vos M, Talati N, Abdollahi MR, Taylor GR, Meyer E, et al. Genetic and epigenetic analysis of recurrent hydatidiform mole. Hum Mutat 2009;30:E629e39. [10] Golubovsky MD. Postzygotic diploidization of triploids as a source of unusual cases of mosaicism, chimerism and twinning. Hum Reprod 2003;18:236e42.