Trisomy 13

From EyeWiki

Disease Entity

Trisomy 13, also known as Patau Syndrome, is a disorder of fetal development with wide-ranging and often severe developmental manifestations, including ocular malformations. The disorder was first described by Patau, et al., in 1960 as "cerebral defects, apparent anophthalmia, cleft palate, hare lip, simian creases, trigger thumbs, polydactyly, and capillary hemangiomata."[1]


Trisomy 13 is an aneuploidy (less or more than 46 chromosomes) in which three copies of chromosome 13—instead of the typical two—are present. Complete, mosaic, and partial forms of trisomy 13 exist.

A complete trisomy occurs when a chromosomal nondisjunction happens during meiosis, a process that occurs in sex cells before fertilization. In such cases, all cells in an organism fertilized by the aneuploid sex cell will harbor an aneuploid genome. Complete trisomy 13 is the most common form of the disorder.[2][3] The vast majority of trisomy 13 cases are due to nondisjunction in the female gamete.[4][5]

Translocation trisomy 13, “when part of chromosome 13 becomes attached (translocated) to another chromosome during the formation of eggs or sperm, or very early in fetal development” accounts for ~20% of cases. This results in two normal copies of chromosome 13 and an extra copy of chromosome 13 attached to another chromosome. Translocation trisomy 13 can be inherited.[3]

Mosaic trisomy 13 occurs when some cells contain euploid genomes and others contain aneuploid genomes. Mosaicism accounts for 5% of trisomy 13 cases.[6] The phenotypes of such cases are generally less severe. Mosaicism occurs due to nondisjunction during mitosis, the process of cell division during development. Only cells derived from the errant cell will harbor extra copies of the chromosome.[7]

Partial trisomy 13 occurs when cells contain two full copies plus an additional portion of chromosome 13. Phenotypes of partial trisomy 13 are also less severe than the complete form.[8]


Phenotypes that arise from aneuploidy are thought to occur due to abnormal levels of gene expression involving genes of the duplicated chromosome.[3][7] The following fetal developmental processes are thought to be disrupted during eye development in trisomy 13:[9]

  • Organogenesis (third-fourth weeks): optic pit changes into the optic vesicle
    • Potential abnormality in trisomy 13: anophthalmia
  • End of fourth week: lens pit and vesicle appear, optic vesicle invaginates to form optic cup
    • Potential abnormalities in trisomy 13: aphakia, congenital cystic eye, disturbed retinal lamination
  • Sixth week: fetal fissures close; lens separates from surface and primary fibers form, retinal differentiation begins, tunica vasculosa begins
    • Potential abnormalities in trisomy 13: coloboma, microphthalmia with orbital cysts, nuclear cataract
  • Seventh-ninth weeks: secondary lens fibers form, secondary vitreous forms, neural crest cells grow into the anterior segment
    • Potential abnormalities in trisomy 13: nuclear cataract, anomalies of the retina and/or vitreous, anterior segment dysgenesis
  • Tenth-twelfth weeks: secondary lens fibers progress, development of ectodermal layers of iris and ciliary body begins
    • Potential abnormalities in trisomy 13: zonular cataract, malformations of anterior segment


The estimated prevalence of trisomy 13 is 1:5,300 in Europe[10] and 1:14,000 in the United States.[11] It is the third most common autosomal trisomy in newborns after trisomy 21 and trisomy 18[12][13] and appears to affect females slightly more frequently than males.[3] The clearest risk factor for fetal aneuploidy is advanced maternal age, as the risk begins to increase significantly after a maternal age of 35 years for trisomies 13, 18, and 21.[13] Most cases are not inherited.[3]

Clinical Features

Systemic Manifestations

Complete trisomy 13 typically results in malformations of multiple organ systems and severe intellectual disability.[3] Common findings include microcephaly; cleft lip and/or palate; polydactyly; hypotonia; failure to thrive; feeding difficulties; cutis aplasia (i.e. missing skin); capillary hemangiomas; low-set ears; deafness; and cardiac, CNS (brain (holoprosencephaly) and spinal cord), and genitourinary anomalies.[7][10][14] Trisomy 13 is the most common cause of holoprosencephaly, which causes severe abnormalities of midline facial structures.[15] Many other systemic features of trisomy 13 have been described.[2][3]

Ocular Manifestations

Figure 1: anophthalmia

The incidence of any particular ocular finding is difficult to ascertain due to the rarity of the disorder and the brief lifespan of affected individuals. These symptoms have been reported in 80-99% of people with trisomy 13[2]:

Figure 2: iris coloboma

These symptoms have been reported in 30-79% of individuals with trisomy 13[2]:

  • Abnormal eyelash morphology[2]
  • Aplasia/hypoplasia of the iris (aniridia)[18]
  • Congenital cataract[10][14]
  • Deeply set eye[2]
  • Iris coloboma (usually inferonasal,[14] Figure 2)
  • Optic atrophy[2]
  • Retinal dysplasia[19][20]
Figure 3: persistent fetal vasculature (PFV). Reproduced with permission from[21] under a Creative Commons license.

Other reported findings include:

  • Acute elevation of intraocular pressure[6]
  • Cartilaginous mass of the anterior segment[14][16]
  • Ciliary body coloboma[20]
  • Coats disease (retinal telangiectasias)[14]
  • Congenital glaucoma/buphthalmos[18][22][23]
  • Corneal opacity[16]
  • Cyclopia[15][19]
  • Dysgenesis of the anterior segment[19][24]
  • Epicanthal folds[25]
  • Nasolacrimal duct obstruction[26]
  • Optic nerve coloboma[27]
  • Persistent fetal vasculature (PFV, Figure 3)[14][21]
  • Persistent tunica vasculosa lentis (PTVL)[14]
  • Sparse or absent eyebrows
  • Upslanting palpebral fissures[17]


Trisomy 13 may be suggested or diagnosed with prenatal screening and testing using fetal ultrasound, biochemical and molecular testing of maternal blood, amniocentesis, and chorionic villus sampling.[2][28] It is associated with increased fetal nuchal translucency, decreased PAPP-A, and decreased β-hCG during first trimester screening.[29] Postnatal diagnostic genetic testing may be undertaken if features of the syndrome are suspected in an infant who was not diagnosed in the prenatal period.


Given the limited life expectancy for most patients with trisomy 13, ophthalmic surgery is generally not recommended. However, for patients with better prognoses and eye conditions amenable to surgical intervention, surgery may be considered.[14][26][30] In one study, among children who underwent surgery, 1-year survival was 68.6%.[31]


Many cases of trisomy 13 end in spontaneous abortion (49% in one study[32]), and most of those born with the condition have a very limited life expectancy. 75-80% of affected infants do not survive beyond the first month, with a higher fatality rate for males.[2][33][34] According to one study, ten-year survival for trisomy 13 was 12.9%. In another study, among affected individuals who lived beyond one year, five-year survival was 84%.[34] The most common causes of death are cardiopulmonary arrest (69%), complications of congenital heart disease (13%), and pneumonia (4%).[33]


Trisomy 13, or Patau Syndrome, is a severe developmental disorder that results in developmental anomalies in multiple organ systems. Ocular pathology is common and varies widely among individuals. Common findings include anophthalmos/microphthalmos, congenital cataract, hypo- or hypertelorism, and inferonasal iris coloboma, but many other findings have been reported.[10][14][16][17][19][18][27][26]

Additional Resources


  1. Patau K, Smith DW, Therman E, Inhorn SL, Wagner HP. Multiple congenital anomaly caused by an extra autosome. Lancet. 1960;1(7128):790-793. doi:10.1016/s0140-6736(60)90676-0
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Trisomy 13. GARD (Genetic and Rare Diseases Information Center). Published April 25, 2016. Accessed December 8, 2020.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Trisomy 13 Syndrome. NORD (National Organization for Rare Disorders). Published 2007. Accessed March 28, 2021.
  4. Bugge M, Collins A, Hertz JM, et al. Non-disjunction of chromosome 13. Hum Mol Genet. 2007;16(16):2004-2010. doi:10.1093/hmg/ddm148
  5. Hall HE, Chan ER, Collins A, et al. The origin of trisomy 13. Am J Med Genet A. 2007;143A(19):2242-2248. doi:10.1002/ajmg.a.31913
  6. 6.0 6.1 Jinawath, N. et al. Mosaic trisomy 13: understanding origin using SNP array. Journal of Medical Genetics 48, 323–326 (2010).
  7. 7.0 7.1 7.2 Korf BR, Irons MB. Cell Division and Chromosomes. In: Human Genetics and Genomics. Vol 4th ed. Wiley-Blackwell; 2012.
  8. Koole FD, Velzeboer CM, van der Harten JJ. Ocular abnormalities in Patau syndrome (chromosome 13 trisomy syndrome). Ophthalmic Paediatr Genet. 1990;11(1):15-21. doi:10.3109/13816819009012944
  9. Koole FD, Velzeboer CM, van der Harten JJ. Ocular abnormalities in Patau syndrome (chromosome 13 trisomy syndrome). Ophthalmic Paediatr Genet. 1990;11(1):15-21. doi:10.3109/13816819009012944
  10. 10.0 10.1 10.2 10.3 10.4 Springett A, Wellesley D, Greenlees R, et al. Congenital anomalies associated with trisomy 18 or trisomy 13: A registry-based study in 16 European countries, 2000-2011. Am J Med Genet A. 2015;167A(12):3062-3069. doi:10.1002/ajmg.a.37355
  11. Rasmussen SA, Wong L-YC, Yang Q, May KM, Friedman JM. Population-based analyses of mortality in trisomy 13 and trisomy 18. Pediatrics. 2003;111(4 Pt 1):777-784. doi:10.1542/peds.111.4.777
  12. Parker SE, Mai CT, Canfield MA, et al. Updated National Birth Prevalence estimates for selected birth defects in the United States, 2004-2006. Birth Defects Res Part A Clin Mol Teratol. 2010;88(12):1008-1016. doi:10.1002/bdra.20735
  13. 13.0 13.1 Savva GM, Walker K, Morris JK. The maternal age-specific live birth prevalence of trisomies 13 and 18 compared to trisomy 21 (Down syndrome). Prenat Diagn. 2010;30(1):57-64. doi:10.1002/pd.2403
  14. 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 Lueder GT. Clinical ocular abnormalities in infants with trisomy 13. Am J Ophthalmol. 2006;141(6):1057-1060. doi:10.1016/j.ajo.2005.12.048
  15. 15.0 15.1 Kruszka P, Muenke M. Syndromes associated with holoprosencephaly. Am J Med Genet C Semin Med Genet. 2018;178(2):229-237. doi:10.1002/ajmg.c.31620
  16. 16.0 16.1 16.2 16.3 Cogan DG, Kuwabara T. Ocular Pathology of the 13-15 Trisomy Syndrome. Arch Ophthalmol. 1964;72:246-253. doi:10.1001/archopht.1964.00970020246021
  17. 17.0 17.1 17.2 Petry P, Polli JB, Mattos VF, et al. Clinical features and prognosis of a sample of patients with trisomy 13 (Patau syndrome) from Brazil. Am J Med Genet A. 2013;161A(6):1278-1283. doi:10.1002/ajmg.a.35863
  18. 18.0 18.1 18.2 Bunting R, Leitch J. Buphthalmos in trisomy 13. Eye (Lond). 2005;19(4):487-488. doi:10.1038/sj.eye.6701454
  19. 19.0 19.1 19.2 19.3 Chan A, Lakshminrusimha S, Heffner R, Gonzalez-Fernandez F. Histogenesis of retinal dysplasia in trisomy 13. Diagn Pathol. 2007;2:48. doi:10.1186/1746-1596-2-48
  20. 20.0 20.1 Allen JC, Venecia G, Opitz JM. Eye findings in the 13 trisomy syndrome. Eur J Pediatr. 1977;124(3):179-183. doi:10.1007/BF00452109
  21. 21.0 21.1 Vislisel JM. Persistent fetal vasculature (PFV). EyeRounds. Published May 26, 2014. Accessed December 9, 2020.
  22. Jaru-Ampornpan P, Kuchtey J, Dev VG, Kuchtey R. Primary congenital glaucoma associated with Patau syndrome with long survival. J Pediatr Ophthalmol Strabismus. 2010;47 Online:e1-4. doi:10.3928/01913913-20100618-09
  23. Keith CG. The ocular manifestations of trisomy 13-15. Trans Ophthalmol Soc U K. 1966;86:435-454.
  24. Hoepner J, Yanoff M. Ocular anomalies in trisomy 13-15: an analysis of 13 eyes with two new findings. Am J Ophthalmol. 1972;74(4):729-737. doi:10.1016/0002-9394(72)90836-7
  25. Mirmohammadsadeghi, A., Akbari, M. R., & Malekpoor, A. (2017). Ocular manifestations in edward's syndrome, a case report and literature review. Journal of Current Ophthalmology, 29(4), 329-331. doi:
  26. 26.0 26.1 26.2 Jain SF, Saoirse Y, Conahan B, Suh D. Ocular Findings in Trisomy 13: Nasolacrimal Duct Stenosis Case Series. OJOph. 2019;09(04):161-164. doi:10.4236/ojoph.2019.94017
  27. 27.0 27.1 Magni R, Pierro L, Brancato R. Microphthalmos with colobomatous orbital cyst in trisomy 13. Ophthalmic Paediatr Genet. 1991;12(1):39-42. doi:10.3109/13816819109023083
  28. Copel JA, Kohari K, Merriam AA. Prenatal testing. In: García-Velasco JA, Seli E, eds. Human Reproductive Genetics. Academic Press; 2020:201-221. doi:10.1016/B978-0-12-816561-4.00012-0
  29. Shiefa, S., Amargandhi, M., Bhupendra, J., Moulali, S. & Kristine, T. First Trimester Maternal Serum Screening Using Biochemical Markers PAPP-A and Free β-hCG for Down Syndrome, Patau Syndrome and Edward Syndrome. Indian Journal of Clinical Biochemistry 28, 3–12 (2012).
  30. Kanigowska K, Grałek M, Seroczyńska M. [Clinical ocular manifestation of Patau’s syndrom (trisomy 13)--own observations]. Klin Oczna. 2011;113(7-9):263-265.
  31. Nelson, K. E., Rosella, L. C., Mahant, S. & Guttmann, A. Survival and Surgical Interventions for Children With Trisomy 13 and 18. JAMA 316, 420 (2016).
  32. Morris JK, Savva GM. The risk of fetal loss following a prenatal diagnosis of trisomy 13 or trisomy 18. Am J Med Genet A. 2008;146A(7):827-832. doi:10.1002/ajmg.a.32220
  33. 33.0 33.1 Baty BJ, Jorde LB, Blackburn BL, Carey JC. Natural history of trisomy 18 and trisomy 13: II. Psychomotor development. Am J Med Genet. 1994;49(2):189-194. doi:10.1002/ajmg.1320490205
  34. 34.0 34.1 Meyer RE, Liu G, Gilboa SM, et al. Survival of children with trisomy 13 and trisomy 18: A multi-state population-based study. Am J Med Genet A. 2016;170A(4):825-837. doi:10.1002/ajmg.a.37495