chromosomal Mosaicism HOME





Trisomy of chromosome 1 is very rare. Trisomy 1 conceptions have not been observed in the large case reports of chromosomal mosaicism discovered in the placenta or the fetus during prenataldiagnosis (Hsu et al, 1997, Hahnemann & Vejerslev 1997). There is one report of a spontaneous pregnancy loss which was found to have trisomy 1 with no fetal development (Hanna et al, 1997).

Trisomy 1 conceptions most likely die before implantation and therefore may occur in preimplantation embryos but are not seen during prenatal diagnosis (Field et al, 1998).

There are, however, cases of mosaicism involving supernumerary marker chromosomes containing chromosome 1 material (and thus partial trisomy 1) (Rothlisberger et al. 2001)

Uniparental Disomy (UPD 1) 

Pulkkinen et al. (1997) and Field et al (1998) each reported a case of maternal UPD1. Gelb et al. (1999), Takizawa et al. (2000), Thompson (2002) and Rivolta et al. (2002) each reported a case of paternal UPD1. These cases were all discovered through rare recessive conditions. In no cases were there features indicative of imprinting, suggesting there are no imprinted genes on chromosome 1 with major phenotypic effects (Field et al, 1998).Three additional cases have since been reported, including one case also mosaic for a supernumerary marker chromosome (Rothlisberger et al. 2001).

Based on the case reports UPD1 is thought to be harmless (i.e. imprinting effects are excluded).

Link to What is UPD?
Link to
Maternal UPD 1page
Link to Paternal UPD 1 page

Internet Links  

  • Human Chromosome 1 Home Page - provide links to useful information for those involved in chromosome 1-related projects. Includes links for Chromosome 1 Workshops, on-line discussion forums, a chromosome 1 researchers directory, information for the general public, and an internet resources page.
  • HUGO Chromosome 1 -Chromosome 1 specific sites
  • Human Chromosome 1 -Each chromosome page provides links to gene maps, sequences, associated genetic disorders, nonhuman genetic models, identified genes, research efforts andlaboratories, and other information as available.
  • Human Chromosome 1 Project, The Sanger Centre - This project endeavors to construct a comprehensive map of human chromosome 1, including all genes and other biologically important sequences, up to the level of the DNA sequence itself.
  • The Human Genome, Chromosome 1
  • NCBI Locuslink for Chromosome 1


Field LL, Tobias R, Robinson WP, Paisey R, Bain S. (1998) Maternal uniparental disomy of chromosome 1 with no apparent phenotypic effects. American Journal of Human Genetics 63:1216-20. PubMed

Gelb BD, Willner JP, Dunn TM, Kardon NB, Verloes A, Poncin J, Desnick RJ (1998) Paternal uniparental disomy for chromosome 1 revealed by molecular analysis of a patient with pycnodysostosis. American Journal of Human Genetics 62:848-854 PubMed

Hahnemann JM, Vejerslev LO. (1997) Accuracy of cytogenetic findings on chorionic villus sampling (CVS)—diagnostic consequences of CVS mosaicism and non-mosaic discrepancy in centers contributing to EUCROMIC 1986-1992. Prenatal Diagnosis 17(9):801-20 PubMed

Hahnemann JM, Vejerslev LO (1997) European Collaborative Research on Mosaicism in CVS (EUCROMIC):fetal and extrafetal cell lineages in 192 gestations with CVS mosaicism involving single autosomal trisomy. American Journal of Medical Genetics 70:179-187 PubMed

Hanna JS, Shires P, Matile G (1997) Trisomy 1 in a clinically recognized pregnancy. American Journal of Human Genetics 68:98 PubMed

Hsu LY, Yu MT, Neu RL, Van Dyke DL, Benn PA, Bradshaw CL, Shaffer LG, Higgins RR, Khodr GS, Morton CC, Wang H, Brothman AR, Chadwick D, Disteche CM, Jenkins LS, Kalousek DK, Pantzar TJ, Wyatt P. (1997) Rare trisomy mosaicism diagnosed in amniocytes, involving an autosome other than chromosomes 13, 18, 20, and 21: karyotype/phenotype correlations. Prenatal Diagnosis 17(3):201-42. PubMed

Ledbetter DH, Engel E. (1995) Uniparental disomy in humans: development of an imprinting map and its implications for prenatal diagnosis. Human Molecular Genetics 4:1757-1764 PubMed

Pulkkinen L, Bullrich F, Czarnecki P, Weiss L, Uitto J (1997) Maternal uniparental disomy of chromosome 1 with reduction to homozygosity of the LAMB3 locus in a patient with Herlitz junctional epidermolysis bullosa. American Journal of Human Genetics 61:611-619 PubMed

Rivolta C, Berson EL, Drya TP (2002) Paternal uniparental heterodisomy with partial isodisomy of chromosome 1 in a patient with retinitis pigmentosa without hearing loss and a missense mutation in the Usher syndrome type II gene USH2A.

Arch Ophthalmol. 2002 Nov;120(11):1566-71 PubMed

Rothlisberger B, Zerova TE, Kotzot D, Buzhievskaya TI, Balmer D, Schinzel A (2001) Supernumerary marker chromosome (1) of paternal origin and maternal uniparental disomy 1 in a developmentally delayed child. J Med Genet 38:885-888

Takizawa Y, Pulkkinen L, Chao SC, Nakajima H, Nakano Y, Shimuzu H, Uitto J (2000) Mutation report: complete paternal uniparental isodisomy of chromosome 1: a novel mechanism for Herlitz junctional epidermolysis bullosa. J Invest Dermatol: 115(2) 307-11

Thompson DA, McHenry CL, Li Y, Richards JE, Othman MI et al. (2002) Retinal dystrophy due to paternal isodisomy for chromosome 1 or chromosome 2, with homoallelism for mutations in RPE65 or MERTK, respectively. Am J Hum Genet 70:224-229

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