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Uniparental Disomy and Genome Imprinting: an Overview

Published online by Cambridge University Press:  01 August 2014

E. Engel*
Affiliation:
University of Geneva Medical School, Geneva, Switzerland
*
Division of Medical Genetics – 1, Rue Michel Servet, 1211 Geneva, Switzerland

Extract

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The following paper is concerned with potential changes in the normal epigenetic process in a diploid individual, when a chromosome pair or segment is inherited from one parent only, instead of the expected biparental contribution. This aberrant mode of transmission arises from the high rate of gamete aneuploidy in humans. It has received the name uniparental disomy (UPD), and has emerged as an important factor in the new field of nontraditional inheritance, depicted in Table 1.

The following definitions may foster a better understanding of this discussion.

UPD is the inheritance of both copies of a chromosome [or chromosomal segment(s)] from a single parent, instead of the normal biparental transmission of the pair. In isodisomy, the two uniparental copies are identical, being derived from the same parental chromosome. In heterodisomy, the two uniparental chromosomes are different, being derived from the homologues of a pair.

Type
Research Article
Copyright
Copyright © The International Society for Twin Studies 1996

References

REFERENCES

1. Engel, E: A new genetic concept: Uniparental disomy and its potential effect, isodisomy. Am J Med Genet 1980; 6: 137143.Google Scholar
2. James, RS, Temple, IK, Patch, C, Thomson, EM, Hassold, T, Jacobs, PA: A systematic search for uniparental disomy in carriers of chromosome translocations. Eur J Hum Genet 1994; 2: 8395.Google Scholar
3. Nicholls, RD, Knoll, JHM, Butler, MG, Karam, S, Lalande, M: Genetic imprinting suggested by maternal heterodisomy in non-deletion Prader-Willi syndrome. Nature 1989; 342: 281285.Google Scholar
4. Malcolm, S, Clayton-Smith, J, Nichols, M, Robb, S, Webb, T, Armour, JAL, Jeffreys, AJ, Pembrey, ME: Uniparental paternal disomy in Angelman's syndrome. Lancet 1991; 337: 694697.Google Scholar
5. Spence, JE, Perciaccante, RG, Greig, GM, Willard, HF, Ledbetter, DH, Hejtmancik, JF, Pollack, MS, O'Brien, WE, Beaudet, AL: Uniparental disomy as a mechanism for human genetic disease. Am J Hum Genet 1988; 42: 217226.Google Scholar
6. Kalousek, DK, Howard-Peebles, PN, Olson, SB, Barrett, IJ, Dorfmann, A, Black, SH, Schulman, JD, Wilson, RD: Confirmation of CVS mosaicism in term placentae and high frequency of intrauterine growth retardation: association with confined placental mosaicism. Prenat Diagn 1991; 11: 743750.CrossRefGoogle ScholarPubMed
7. Wang, J-CC, Passage, MB, Yen, PH, Shapiro, LJ, Mohandas, TK: Uniparental heterodisomy for chromosome 14 in a phenotypically abnormal familial balanced 13/14 Robertsonian translocation carrier. Am J Hum Genet 1991; 48: 10691074.Google Scholar
8. Purvis-Smith, SG, Saville, T, Manass, S, Yip, M-Y, Lam-Po-Tang, PRL, Duffy, B, Johnston, H, Leigh, D, McDonald, B: Uniparental disomy 15 resulting from “correction” of an initial trisomy 15. Am J Hum Genet 1992; 50: 13481350.Google Scholar
9. Cassidy, SB, Lai, LW, Erickson, RP, Magnusson, L, Thomas, E, Gendron, R, Herrmann, J: Trisomy 15 with loss of the paternal 15 as a cause of Prader-Willi syndrome due to maternal disomy. Am J Hum Genet 1992; 51: 701708.Google Scholar
10. Voss, R, Ben-Simon, E, Avital, A, Godfrey, S, Zlotogora, J, Dagan, J, Tikoschinski, Y, Hillel, J: Isodisomy of chromosome 7 in a patient with cystic fibrosis: Could uniparental disomy be common in humans? Am J Hum Genet 1989; 45: 373380.Google Scholar
11. Pentao, L, Lewis, RA, Ledbetter, DH, Patel, PI, Lupski, JR: Maternal uniparental isodisomy for chromosome 14: Association with autosomal recessive rod monochromacy. Am J Hum Genet 1992; 50: 690699.Google Scholar
12. Freeman, SB, May, KM, Pettay, P, Fernhoff, PM, Hassold, TJ: Paternal uniparental disomy in a child with a balanced 15; 15 translocation and Angelman syndrome. Am J Med Genet 1993; 45: 625630.Google Scholar
13. Bottani, A, Robinson, WP, DeLozier-Blanchet, CD, Engel, E, Morris, M, Schmitt, B, Thun Hohenstein, L, Schinzel, A: Angelman syndrome due to paternal uniparental disomy of chromosome 15: A milder phenotype? Am J Med Genet 1994; 51: 3540.CrossRefGoogle ScholarPubMed
14. Saitoh, S, Mutirangura, A, Kuwano, A, Ledbetter, DH, Niikawa, N: Isochromosome 15q of maternal origin in two Prader-Willi syndrome patients previously diagnosed erroneously as cytogenetic deletions. Am J Med Genet 1994; 50: 6467.Google Scholar
15. Bettio, D, Giardino, D, Rizzi, N, Barantani, E, Volpi, L, Riva, P: Maternal uniparental disomy in a Prader-Willi patient with a t (15q;15q) and pituitary adenoma: Fortuity or a rare association? Int. Symp. Genomic Imprinting, Florence, 1994, A 3.Google Scholar
16. Petersen, MB, Bartsch, O, Adelsberger, PA, Mikkelsen, M, Schwinger, E, Antonarakis, SE: Uniparental isodisomy due to duplication of chromosome 21 occurring in somatic cells monosomic for chromosome 21. Genomics 1992; 13: 269274.Google Scholar
17. Robinson, WP, Wagstaff, , Bernasconi, F, Baccichelti, B, Artifoni, L, Franzoni, E, Suslak, L, Shih, L-Y, Aviv, H, Schinzel, AA: Uniparental disomy explains the occurrence of the Angelman or Prader-Willi syndrome in patients with an additional small inv-dup (15) chromosome. J Med Genet 1993; 30: 756760.Google Scholar
18. Temple, IK, James, RS, Sitch, FL, Howell, WM, Dennis, NR, Crolla, JA: An imprinted gene on chromosome 6 associated with neonatal diabetes: The importance of a systematic search for uniparental disomy. Int. Symp. Genomic Imprinting, Florence, 1994, A 37.Google Scholar
19. Robinson, WP, Bernasconi, F, Basaran, S, Yüksel-Apak, M, Neri, G, Serville, F, Balicek, P, Haluza, R, Farah, LMS, Lüleci, G, Schinzel, AA: A somatic origin of homologous Robertsonian translocations and isochromosomes. Am J Hum Genet 1994; 54: 290302.Google Scholar
20. Cavenee, WK, Dryja, TP, Phillips, RA, Benedict, WF, Godbout, R, Gallie, BL, Murphree, AL, Strong, LC, White, RL: Expression of recessive alleles by chromosomal mechanisms in retinoblastoma. Nature 1983; 305: 779784.CrossRefGoogle ScholarPubMed
21. Henry, I, Bonaïti-Pellié, C, Chenhensse, V, Beldjord, C, Schwartz, C, Utermann, G, Junien, C: Uniparental paternal disomy in a genetic, cancer predisposing syndrome. Nature 1991; 351: 665667.Google Scholar
22. DeLozier-Blanchet, CD, Engel, E, Extermann, P, Pastori, B: Trisomy 7 in chorionic villi: Follow up studies of pregnancy, normal child, and placental clone anomalies. Prenat Diagn 1988; 8: 281286.Google Scholar
23. Engel, E, DeLozier-Blanchet, CD: Uniparental disomy, isodisomy and imprinting: Probable effects in man and strategies for their detection. Am J Med Genet 1991; 40: 432439.Google Scholar
24. Engel, E: Uniparental disomy revisited, the first twelve years. Am J Med Genet 1993; 46: 670674.Google Scholar
25. Kalousek, DK, Langlois, S, Barrett, I, Yam, I, Wilson, DR, Howard-Peebles, PN, Johnson, MP, Giorgiutti, E: Uniparental disomy for chromosome 16 in humans. Am J Hum Genet 1993; 52: 816.Google ScholarPubMed
26. Bennett, P, Vaugh, J, Henderson, D, Longhna, S, Moore, G: Association between confined placental trisomy, fetal uniparental disomy and early intrauterine growth retardation. Lancet 1992; 340: 12841285.Google Scholar
27. Dorfmann, AD, Perszyk, J, Robinson, P, Black, SH, Schulman, JD: Rare non mosaic trisomies in chorionic villus tissue not confirmed at amniocentesis. Prenat Diagn 1992; 12: 899902.Google Scholar
28. Dworniczak, B, Koppers, B, Bogdanova, N, Exeler, R, Tercanli, S, Holzgreve, W, Horst, J, Miny, P: Clinical follow up of uniparental disomy 16 (abstract 28). Am J Hum Genet 1994; (55) Suppl. A7.Google Scholar
29. Dworniczak, B, Koppers, B, Kuriemann, G, Holzgreve, W, Horst, J, Miny, P: Uniparental disomy with normal phenotype. Lancet 1992; 340: 1285.Google Scholar
30. Willatt, LR, Clare Davison, BC, Goudie, D, Alexander, J, Dysen, HM, Jenks, PE, Ferguson-Smith, ME: A male with trisomy 9 mosaicism and maternal uniparental disomy for chromosome 9 in the euploid cell line. J Med Genet 1992; 29: 742744.Google Scholar
31. Harrison, KB, Eisenger, K, Yeboa, KA, Brown, S: Maternal uniparental disomy of chromosome 2 in a baby with trisomy 2 mosaicism in amniotic fluid culture (abstract 603). Am J Hum Genet 1994; 55 (Suppl.) A106.Google Scholar
32. Kalousek, DK, Langlois, S, Harrison, KJ, Wilson, RD, McGillivray, BC, Yong, SL, Barrett, IJ, Johnson, M, Howard-Peebles, P: Confined placental mosaicism and uniparental disomy (abstract 39). Am J Hum Genet 1994; (55) Suppl: A9.Google Scholar
33. Hogge, WA, Schonberg, SA, Golbus, MS: Chorionic villus sampling: Experience of the first 1000 cases. Am J Obstet Gynecol 1986; 154: 12491252.Google Scholar
34. Mikkelsen, M, Aymé, S: Chromosome findings in chorionic villi: A collaborative study. 7th Int Congr Hum Genet, Berlin, 1986.Google Scholar
35. Simoni, G, Fraccaro, M, Gimelli, G: False positive and false negative findings on chorionic villus sampling. Prenat Diagn 1987; 7: 671672.Google Scholar
36. Ledbetter, DH, Martin, AO, Verlinsky, Y, et al: Cytogenetic results of chorionic villus sampling: High success rate and diagnostic accuracy in the United States collaborative study. Am J Obstet Gynecol 1990; 162: 495501.Google Scholar
37. DeLozier-Blanchet, CD: Anomalies cytogénétiques et fonction placentaire. Rev Fr Gynécol Obstét 1991; 86: 723729.Google Scholar
38. Antonarakis, S, Blouin, JL, Mäher, J, Avramopoulos, D, Thomas, G, Talbot, CC: Maternai uni-parental disomy for human chromosome 14, due to loss of a chromosome 14 from somatic cells with t(13;14) trisomy 14. Am J Hum Genet 1993; 52: 11451152.Google Scholar
39. Devi, AS, Velinor, M, Kamoth, V, Eisenfeld, L, Neu, R, Ciarleglio, L, Greenstein, R, Benn, P: Variable clinical expression of mosaic trisomy 16 in the new born infant. Am J Med Genet 1993; 47: 294298.Google Scholar
40. Sirchia, SM, DeAndreis, C, Pariani, S, Grimoldi, MG, Molinari, A, Buscaglia, M, Simoni, G: Chromosome 14 maternal uniparental disomy in the euploid cell line of a fetus with mosaic 46,XX/47,XX, + 14 karyotype. Hum Genet 1994; 94: 355358.Google Scholar
41. DeLozier-Blanchet, CD, Hahnemann, JM, Veierslev, LO: Eucromic (European collaborative research on mosaicisms in chorionic villus sampling (abstract 40). Am J Hum Genet 1994; 55 (suppl): A10.Google Scholar
42. Morichon-Delvallez, N, Seques, B, Pinson, MP, Bérubé, D, Dommergues, M, Aubry, MC, Cessot, F, Lyonnet, S, Munnich, A, Vekemans, M: Maternal uniparental disomy for chromosome 14 by secondary non-disjunction of an initial trisomy (abstract 2224). Am J Hum Genet 1994; (55 suppl): A379.Google Scholar
43. Spinner, NB, Rand, E, Bucan, M, Jirik, F, Gogolin-Ewens, C, Riethman, HC, McDonald-McGinn, DM, Zackaï EH: Paternal uniparental isodisomy. for human chromosome 20 and absence of external ears (abstract 674). Am J Hum Genet 1994; (55 suppl): A118.Google Scholar
44. Milunsky, JM, Wyandt, HE, Amos, JA, Kang, Z, Huang, XL, Elias, E, Milunsky, A: Trisomy 15 mosaicism in uniparental disomy (UPD) in a live born infant (abstract 636). Am J Hum Genet 1994; 55 (suppl): A112.Google Scholar
45. Rocklin, ML, Elder, FFB, Ledbetter, DH, Christian, S, Huang, B, Rosenberg, H, Sheppard, C, Wilkins, I: True fetal trisomy 15 mosaicism with maternal uniparental disomy (abstract 1677). Am J Hum Genet 1994; 55 (suppl): A286.Google Scholar
46. Temple, IK, Cockwell, A, Hassold, T, Pettay, D, Jacobs, P: Maternal uniparental disomy for chromosome 14. J Med Genet 1991; 28: 511514.Google Scholar
47. Hamabe, JI, Fukushima, Y, Harada, N, Abe, K, Matsuo, N, Nagai, T, Yoshioka, A, Tonoki, H, Tsukino, R, Niikawa, N: Molecular study of the Prader-Willi syndrome: Deletion, RFLP and phenotype analyses of 50 patients. Am J Med Genet 1991, 41: 5463.Google Scholar
48. Smeets, DMCF, Hamel, BCJ, Nelen, MR, Smeets, HJM, Bollen, JHM, Smits, APT, Ropers, HH, Van Oost, BA: Prader Willi syndrome and Angelman syndrome in cousins from a family with a translocation between chromosomes 6 and 15. New Engl J Med 1992; 326: 807811.Google Scholar
49. Smith, A, Robson, L, Neumann, A, Mulcahy, M, Chabros, M, Deng, V, Woodage, ZM, Trent, RJ: Fluorescence in situ hybridization and molecular studies used in the characterisation of a Robertsonian translocation (13ql5q) in Prader-Willi syndrome. Clin Genet 1993; 43: 58.Google Scholar
50. Healey, S, Powell, F, Battersby, M, Chenevix-Trench, G, McGill, J: Distinct phenotype in maternal uniparental disomy of chromosome 14. Am J Med Genet 1994; 51: 147149.Google Scholar
51. Tomkins, DJ, Waye, JS, Whelan, DT, Cox, DW: Maternal uniparental disomy of chromosome 14 in a boy with t(14q;14q) associated with a paternal t(13q;14q) (abstract 685). Am J Hum Genet 1994; 55 (suppl): A120.Google Scholar
52. Driscoll, DJ: Genomic imprinting in humans. Mol Genet Med 1994; 4: 3777.Google Scholar
53. Driscoll, DJ, Waters, MF, Williams, CA, Zori, RT, Glenn, CC, Avidano, KM, Nicholls, RD: A DNA methylation imprint, determined by the sex of the parent, distinguishes the Angelman and Prader-Willi syndromes. Genomics 1992; 13: 917924.Google Scholar
54. Schinzel, AA: Uniparental disomy and gene localization. Am J Hum Genet 1991; 48: 424425.Google Scholar
55. Spotila, LD, Sereda, L, Prockop, DJ: Partial isodisomy for maternal chromosome 7 and short stature in an individual with a mutation at the COLIA2 locus. Am J Hum Genet 1992; 51: 13961405.Google Scholar
56. Eggerding, FA, Schonberg, SA, Chehab, FF, Norton, ME, Cox, VA, Epstein, CJ: Uniparental isodisomy for paternal 7p and maternal 7q in a child with growth retardation. Am J Hum Genet 1994; 55: 255263.Google Scholar
57. Williams, JC, Brown, KW, Mott, MG, Montland, NJ: Maternal allele loss in Wilms tumor. Lancet 1989; i: 283284.CrossRefGoogle Scholar
58. Betz, A, Turleau, C, deGrouchy, J: Heterozygotie et homozygotie pour une inversion péricen-trique du 3 humain. Am Génét 1974; 17: 7780.Google Scholar
59. Palmer, CG, Schwartz, S, Hodes, ME: Transmission of a balanced homologous t(22q;22q) translocation from mother to normal daughter. Clin Genet 1980; 17: 418422.Google Scholar
60. Kirkels, VGHJ, Hustinx, TWJ, Scheres, JMJC: Habitual abortion and translocation (22q;22q): Unexpected transmission from mother to her phenotypically normal daughter. Clin Genet 1980; 18: 456461.Google Scholar
61. Stallard, R, Krueger, S, Schwartz, S: Uniparental disomy (UD) in a normal female due to transmission of a maternal t(13q;13q). Am J Hum Genet 1993; (53) (suppl): 256.Google Scholar
62. Slater, H, Shaw, JH, Dawson, G, Bankur, A, Forrest, SM: Maternal uniparental disomy of chromosome 13 in a phenotypically normal child. J Med Genet 1994; 31: 644646.CrossRefGoogle Scholar
63. Brzustowicz, LM, Alletto, BA, Matscoane, D, Theve, R, Michand, L, Chatkupt, S, Sugarman, E, Penchaszaden, GK, Suslak, L, Koenigsberger, MR, Gilliam, TC, Handelen, BL: Paternal isodisomy for chromosome 5 in a child with spinal muscular atrophy. Am J Hum Genet 1994; 54: 482488.Google Scholar
64. Welch, TR, Beischel, LS, Choi, E, Balakrishnan, K, Bishof, NA: Uniparental isodisomy 6 associated with deficiency of the fourth components of complement. J Clin Invest 1990; 86: 675678.Google Scholar
65. Abramowicz, MJ, Adrien, M, Dupont, E, Dorchy, H, Parma, J, Duprez, L, Ledley, FD, Courtens, W, Vamos, E: Isodisomy for chromosome 6 in a newborn with methylmalonic acidemia and agenesis of pancreatic beta cells causing diabetes mellitus. J Clin Invest 1994; 94: 418421.Google Scholar
66. Höglund, P, Holmberg, C, de la Chapelle, A, Kore, J: Paternal isodisomy for chromosome 7 is compatible with normal growth and development in a patient with congenital chloride diarrhea. Am J Hum Genet 1994; 55: 747752.Google Scholar
67. Saliralo, T, Makitie, O, Ruuskanen, O, de la Chapelle, A, Kaitila, J: Maternal uniparental disomy may result in an unusually severe cartilage-hair hypoplasia. Int Symp Genomic Imprinting, Florence, 1994, A33.Google Scholar
68. Beldjord, C, Henry, I, Bennani, C, Vanhaeke, D, Labie, D: Uniparental disomy: A novel mechanism for thalassemia major. Blood 1992; 80: 287289.Google Scholar
69. Woodage, T, Prasad, M, Dixon, JW, Selby, RE, Romain, DR, Columbano-Green, LM, Graham, D, Rogan, PK, Serp, JR, Smith, A, Trent, RE: Bloom syndrome and maternal uniparental disomy for chromosome 15. Am J Hum Genet 1994; 55: 7480.Google Scholar
70. Ngo, KY, Lee, J, Dixon, B, Liu, D, Jones, OW: Paternal, uniparental isodisomy in a hydrops fetalis α-thalassemia fetus. Am J Hum Genet 1993; 53 (suppl): 1207.Google Scholar
71. Korenstein, A, Ravia, Y, Avivi, L: Uniparental disomy of chromosome 16 in offsprings of familial Mediterranean fever (FMF) patients treated with colchicine (abstract 616). Am J Hum Genet 1994; 55 (suppl): A109.Google Scholar
72. Carpenter, NJ, Say, B, Barber, ND: A homozygote for pericentric inversion of chromosome 4. J Med Génét 1982; 19: 469471.Google Scholar
73. Lindenbaum, RH, Woods, CG, Norbury, CG, Povey, S, Rysieck, G: An individual with maternal disomy of chromosome 4 and iso(4p), iso(4q). Am J Hum Genet 1991, 49 (suppl): 285.Google Scholar
74. Diamond, TM, Mueller, OT, Sutcliffe, M, Papenhausen, PR, Tedesco, TA, Kouseff, BG: Uniparental disomy for chromosome 14 Evidence for an imprinting effect. Am J Hum Genet 1993; 53: 541.Google Scholar
75. Schinzel, AA, Robinson, WP, Binkert, F, Torresani, T, Werder, EA: Exclusively paternal X chromosomes in a girl with short stature. Hum Genet 1993; 92: 175178.Google Scholar
76. Créau-Goldberg, N, Gegoine, A, Delabar, J, Cochet, C, Cabanis, MO, Stehelin, D, Turleau, C, deGrouchy, J: Maternal origin of a de novo balanced t(21q;21q) identified by ets-2 polymorphisms. Hum Genet 1987; 76: 396398.Google Scholar
77. Blouin, JL, Avramopoulos, D, Pangalos, C, Antonarakis, SE: Normal phenotype with paternal uniparental isodisomy for chromosome 21. Am J Hum Genet 1993; 53: 10741078.Google Scholar
78. Schinzel, AA, Basaran, S, Bernasconi, F, Karaman, B, Yüksel-Apak, M, Robinson, WP: Maternal uniparental disomy 22 has no impact on the phenotype. Am J Hum Genet 1994; 54: 2124.Google Scholar
79. Avivi, L, Korenstein, A, Braier-Goldstein, O, Goldman, B, Ravia, Y: Uniparental disomy of sex chromosomes in man (abstract 33). Am Soc Hum Genet 1993; E1 (suppl): A11.Google Scholar
80. Vidaud, D, Vidaud, M, Plassa, F, Gazengel, C, Noël, B, Goossens, M: Father-to-son transmission of hemophilia A due to uniparental disomy, (abstract 889). 40th Ann Meet Am Soc Hum Genet, 1989.Google Scholar
81. Bricarelli, D, Borrone, C, Mantero, MM, Perfumo, C, Guelfi, M, Panucci, E, Corrillo, DA: Paternal uniparental disomy for chromosome 14. Int Symp Genomic Imprinting, Florence, 1994; SR/15.Google Scholar
82. Vaughan, J, Ali, Z, Bower, S, Bennnett, P, Chard, T, Moore, G: Human maternal uniparental disomy for chromosome 16 and fetal development. Prenat Diagn 1994; 14: 751756.Google Scholar
83. Ledbetter, DH, Riccardi, VM, Airhart, SD, Strobel, RJ, Keenan, BS, Crawford, JD: Deletions of chromosome 15 as a cause of the Prader-Willi syndrome. New Engl J Med 1981; 304: 325329.Google Scholar
84. Kaplan, LC, Wharton, R, Elias, E, Mandell, F, Donlon, T, Latt, SA: Clinical heterogeneity associated with deletions in the long arm of chromosome 15: Report of 3 new cases and their possible significance. Am J Med Genet 1987; 28: 4553.CrossRefGoogle Scholar
85. Wagstaff, J, Knoll, JHM, Glatt, KA, Shugart, JJ, Sommer, A, Lalande, M: Maternal but not paternal transmission of 15q 11-13 linked non deletion Angelman syndrome leads to phenotypic expression. Nat Genet 1992; 1: 291294.Google Scholar
86. Özcelik, T, Leff, S, Robinson, W, Darlon, P, Lalande, M, Saupiver, E, Schinzel, A: Small nuclear ribonucleoprotein polysephide N (SNRPN): An expressed gene in the Prader Willi syndrome critical region. Nat Genet 1992; 2: 265269.Google Scholar
87. Beaudet, AL, Nakao, M, Durtschi, BA, Mutirangevra, A, Ledbetter, DH, Sutcliffe, JS: Molecular analysis of the Prader-Willi Angelman critical region identifies a cluster of imprinted genes. J Cell Biochem 1994; 18 (suppl A): 205.Google Scholar
88. Reis, A, Dittrich, B, Greger, V, Buiting, K, Lalande, M, Gillessen-Kaeschbach, G, Anvret, M, Horsthemko, B: Imprinting mutations suggested by abnormal DNA methylation patterns in familial Angelman and Prader-Willi syndromes. Am J Hum Genet 1994; 54: 741747.Google Scholar
89. Nicholls, RD: New insights reveal complex mechanisms involved in genomic imprinting. Am J Hum Genet 1994; 54: 733740.Google Scholar
90. Steenman, MJC, Rainier, S, Dobry, CJ, Grundy, P, Horan, IL, Feinberg, AP: Loss of imprinting of IGF2 is linked to reduced expression and abnormal methylation of H19 in Wilms tumor. Nat Genet 1994; 7: 433439.Google Scholar
91. Copeland, NG, Jenkins, NA, Gilbert, DJ: A genetic linkage map of the mouse: Current Applications and future prospects. Science 1993; 262: 5766.Google Scholar