Medscape is available in 5 Language Editions – Choose your Edition here.


Trisomy 18 Clinical Presentation

  • Author: Harold Chen, MD, MS, FAAP, FACMG; Chief Editor: Luis O Rohena, MD  more...
Updated: Feb 05, 2016


Prenatal history in trisomy 18

See the list below:

  • Maternal polyhydramnios possibly related to defective sucking and swallowing reflexes in utero
  • Oligohydramnios secondary to renal defects
  • Disproportionately small placenta
  • Single umbilical artery
  • Weak fetal activity
  • Fetal distress

Clinical history in trisomy 18

See the list below:



See the list below:

  • Neurological
    • Delayed psychomotor development and mental retardation (100%)
    • Neonatal hypotonia followed by hypertonia, jitteriness, apnea, and seizures
    • Malformations (eg, microcephaly, cerebellar hypoplasia, meningoencephalocele, anencephaly, hydrocephaly, holoprosencephaly, Arnold-Chiari malformation, hypoplasia or aplasia of the corpus callosum, defective falx cerebri, frontal lobe defect, migration defect, arachnoid cyst, myelomeningocele)
  • Cranial - Microcephaly, elongated skull, narrow bifrontal diameter, wide fontanels, and prominent occiput
  • Facial - Microphthalmia, ocular hypertelorism, epicanthal folds, short palpebral fissures, iris coloboma, cataract, corneal clouding, abnormal retinal pigmentation, short nose with upturned nares, choanal atresia, micrognathia or retrognathia, microstomia, narrow palatal arch, infrequent cleft lip and cleft palate, preauricular tags and low-set, and malformed ears (faunlike with flat pinnae and a pointed upper helix)
  • Skeletal - Severe growth retardation, characteristic hand posture (ie, clenched hands with the index finger overriding the middle finger and the fifth finger overriding the fourth finger), camptodactyly, radial hypoplasia or aplasia, thumb aplasia, syndactyly of the second and third digits, arthrogryposis, rocker-bottom feet with prominent calcanei, talipes equinovarus, hypoplastic nails, dorsiflexed great toes, short neck with excessive skin folds, short sternum, narrow pelvis, and limited hip abduction
  • Cardiac
  • Pulmonary -Pulmonary hypoplasia and abnormal lobation of the lung
  • GI -Omphalocele, malrotation of the intestine, ileal atresia, common mesentery, Meckel diverticulum, esophageal atresia with or without tracheoesophageal fistula, diaphragmatic eventration, prune belly anomaly, diastasis recti, absent gallbladder, absent appendix, accessory spleens, exstrophy of Cloaca, pyloric stenosis, imperforate or malpositioned anus, pilonidal sinus, and hernias (ie, umbilical, inguinal, diaphragmatic)
  • Genitourinary
    • Micromulticystic kidneys, double ureters, megaloureters, hydroureters, hydronephrosis, horseshoe kidneys, and unilateral renal agenesis
    • Cryptorchidism, hypospadias, and micropenis in males
    • Hypoplasia of labia and ovaries, bifid uterus, hypoplastic ovaries, and clitoral hypertrophy in females
  • Endocrine - Thymic hypoplasia, thyroid hypoplasia, and adrenal hypoplasia
  • Dermal (ie, dermatoglyphics) - Increased number of simple arches on the fingertips, transverse palmar crease, increased atd angle, and clinodactyly of the fifth fingers with a single flexion crease
  • Phenotypic spectrum of mosaic trisomy 18[13]
    • Phenotype of individuals with mosaic trisomy 18, in general, widely varies. Some individuals who have the complete trisomy 18 (typical Edwards syndrome) phenotype experience early death whereas others are phenotypically completely normal. The latter group is exemplified by several normal-appearing adults with mosaic trisomy 18 who were identified only after giving birth to children with complete trisomy 18.
    • Anomalies widely vary, most at low frequencies, including microcephaly, delayed bone age, brachydactyly, congenital heart defects, developmental delay, short stature, and premature ovarian failure.
    • Intellectual capabilities range from profound intellectual disability to above-average intelligence. No correlation between the percentage of trisomic cells in either fibroblasts or leukocytes and the individual’s phenotype or intellectual function is noted.


See the list below:

  • Full trisomy 18 is responsible for 95% of Edwards syndrome cases. Mosaicism and translocations cause few cases. An extra chromosome 18 is responsible for the phenotype.
  • The incidence rate increases with advanced maternal age. In approximately 90% of cases, the extra chromosome is maternal in origin, with meiosis II errors occurring twice as frequently as meiosis I errors. This is in contrast to other human trisomies, which exhibit a higher frequency of nondisjunction in maternal meiosis I. Among cases resulting from paternal nondisjunction, most are the result of postzygotic mitotic errors.
  • Although full trisomy results from meiotic nondisjunction, mosaic trisomy is due to postzygotic mitotic nondisjunction. Mosaic trisomy 18 occurs when both a trisomy 18 cell line and a normal cell line are present in the same individual. Mosaic trisomy 18 accounts for approximately 5% of trisomy 18 cases.[14] The clinical phenotype varies depending on the level of mosaicism and the tissue involved and ranges from the complete trisomy 18 phenotype to no dysmorphic features and normal intelligence.[15]
  • Translocation trisomy gives rise to partial trisomy 18 syndrome. Partial trisomy 18 occurs when a segment of chromosome 18 is present in triplicate, often resulting from a balanced translocation carried by one parent. It accounts for approximately 2% of trisomy 18 cases.
  • The smallest extra region necessary for expression of serious anomalies of trisomy 18 appears to be 18q11-12.
Contributor Information and Disclosures

Harold Chen, MD, MS, FAAP, FACMG Professor, Department of Pediatrics, Louisiana State University Medical Center

Harold Chen, MD, MS, FAAP, FACMG is a member of the following medical societies: American Academy of Pediatrics, American College of Medical Genetics and Genomics, American Medical Association, American Society of Human Genetics

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Lois J Starr, MD, FAAP Assistant Professor of Pediatrics, Clinical Geneticist, Munroe Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center

Lois J Starr, MD, FAAP is a member of the following medical societies: American Academy of Pediatrics, American College of Medical Genetics and Genomics

Disclosure: Nothing to disclose.

Chief Editor

Luis O Rohena, MD Chief, Medical Genetics, San Antonio Military Medical Center; Assistant Professor of Pediatrics, Uniformed Services University of the Health Sciences, F Edward Hebert School of Medicine; Assistant Professor of Pediatrics, University of Texas Health Science Center at San Antonio

Luis O Rohena, MD is a member of the following medical societies: American Academy of Pediatrics, American Chemical Society, American College of Medical Genetics and Genomics, American Society of Human Genetics

Disclosure: Nothing to disclose.

Additional Contributors

Michael Fasullo, PhD Senior Scientist, Ordway Research Institute; Associate Professor, State University of New York at Albany; Adjunct Associate Professor, Center for Immunology and Microbial Disease, Albany Medical College

Michael Fasullo, PhD is a member of the following medical societies: Radiation Research Society, American Society for Biochemistry and Molecular Biology, Genetics Society of America, Environmental Mutagenesis and Genomics Society

Disclosure: Nothing to disclose.

  1. Edwards JH, Harnden DG, Cameron AH, et al. A new trisomic syndrome. Lancet. 1960 Apr 9. 1:787-90. [Medline].

  2. Smith DW, Patau K, Therman E, Inhorn SL. A new autosomal trisomy syndrome: multiple congenital anomalies caused by anextra chromosome. J Pediatr. 1960 Sep. 57:338-45. [Medline].

  3. Cereda A, Carey JC. The trisomy 18 syndrome. Orphanet J Rare Dis. 2012 Oct 23. 7:81. [Medline]. [Full Text].

  4. Rasmussen SA, Wong LY, Yang Q, May KM, Friedman JM. Population-based analyses of mortality in trisomy 13 and trisomy 18. Pediatrics. 2003 Apr. 111(4 Pt 1):777-84. [Medline].

  5. 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. 2015 Dec 10. [Medline].

  6. Kelly M, Robinson BW, Moore JW. Trisomy 18 in a 20-year-old woman. Am J Med Genet. 2002 Nov 1. 112(4):397-9. [Medline].

  7. Lebel RR, Roberson J, Van Dyke DL. Regarding trisomy 18. Am J Med Genet A. 2006 May 1. 140(9):964-5. [Medline].

  8. Shanske AL. Trisomy 18 in a second 20-year-old woman. Am J Med Genet A. 2006 May 1. 140(9):966-7. [Medline].

  9. Embleton ND, Wyllie JP, Wright MJ, et al. Natural history of trisomy 18. Arch Dis Child Fetal Neonatal Ed. 1996 Jul. 75(1):F38-41. [Medline].

  10. Nicolaidis P, Petersen MB. Origin and mechanisms of non-disjunction in human autosomal trisomies. Hum Reprod. 1998 Feb. 13(2):313-9. [Medline]. [Full Text].

  11. Crider KS, Olney RS, Cragan JD. Trisomies 13 and 18: population prevalences, characteristics, and prenatal diagnosis, metropolitan Atlanta, 1994-2003. Am J Med Genet A. 2008 Apr 1. 146(7):820-6. [Medline].

  12. 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 Apr 1. 146(7):827-32. [Medline].

  13. Tucker ME, Garringer HJ, Weaver DD. Phenotypic spectrum of mosaic trisomy 18: two new patients, a literature review, and counseling issues. Am J Med Genet A. 2007 Mar 1. 143(5):505-17. [Medline].

  14. Carey JC. Trsiomy 18 and trisomy 13 syndromes. Cassidy SB, Allanson JE. Management of Genetic Syndromes. 2nd. New York, NY: Wiley-Liss; 2005. 555-68.

  15. Bettio D, Levi Setti P, Bianchi P, Grazioli V. Trisomy 18 mosaicism in a woman with normal intelligence. Am J Med Genet A. 2003 Jul 15. 120(2):303-4. [Medline].

  16. Staples AJ, Robertson EF, Ranieri E, Ryall RG, Haan EA. A maternal serum screen for trisomy 18: an extension of maternal serum screening for Down syndrome. Am J Hum Genet. 1991 Nov. 49(5):1025-33. [Medline]. [Full Text].

  17. Perni SC, Predanic M, Kalish RB, Chervenak FA, Chasen ST. Clinical use of first-trimester aneuploidy screening in a United States population can replicate data from clinical trials. Am J Obstet Gynecol. 2006 Jan. 194(1):127-30. [Medline].

  18. Breathnach FM, Malone FD, Lambert-Messerlian G, et al, for the First and Second Trimester Evaluation of Risk (FASTER) Research Consortium. First- and second-trimester screening: detection of aneuploidies other than Down syndrome. Obstet Gynecol. 2007 Sep. 110(3):651-7. [Medline].

  19. Cereda A, Carey JC. The trisomy 18 syndrome. Orphanet J Rare Dis. 2012 Oct 23. 7:81. [Medline]. [Full Text].

  20. Wei S, Siu VM, Decker A, Quigg MH, Roberson J, Xu J. False-positive prenatal diagnosis of trisomy 18 by interphase FISH: hybridization of chromosome 18 alpha-satellite DNA probe (D18Z1) to the heterochromatic region of chromosome 9. Prenat Diagn. 2007 Nov. 27(11):1064-6. [Medline].

  21. Caughey AB, Hopkins LM, Norton ME. Chorionic villus sampling compared with amniocentesis and the difference in the rate of pregnancy loss. Obstet Gynecol. 2006 Sep. 108(3 Pt 1):612-6. [Medline].

  22. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 88, December 2007. Invasive prenatal testing for aneuploidy. Obstet Gynecol. 2007 Dec. 110(6):1459-67. [Medline].

  23. ACOG Committee on Practice Bulletins. ACOG Practice Bulletin No. 77: screening for fetal chromosomal abnormalities. Obstet Gynecol. 2007 Jan. 109(1):217-27. [Medline].

  24. Lo YM, Corbetta N, Chamberlain PF, et al. Presence of fetal DNA in maternal plasma and serum. Lancet. 1997 Aug 16. 350(9076):485-7. [Medline].

  25. Ashoor G, Syngelaki A, Wagner M, Birdir C, Nicolaides KH. Chromosome-selective sequencing of maternal plasma cell-free DNA for first-trimester detection of trisomy 21 and trisomy 18. Am J Obstet Gynecol. 2012 Apr. 206(4):322.e1-5. [Medline].

  26. Wiedmeier SE, Henry E, Christensen RD. Hematological abnormalities during the first week of life among neonates with trisomy 18 and trisomy 13: data from a multi-hospital healthcare system. Am J Med Genet A. 2008 Feb 1. 146(3):312-20. [Medline].

  27. Sepulveda W, Wong AE, Dezerega V. First-trimester sonographic findings in trisomy 18: a review of 53 cases. Prenat Diagn. 2010 Mar. 30(3):256-9. [Medline].

  28. Zheng Y, Zhou XD, Zhu YL, Wang XL, Qian YQ, Lei XY. Three- and 4-dimensional ultrasonography in the prenatal evaluation of fetal anomalies associated with trisomy 18. J Ultrasound Med. 2008 Jul. 27(7):1041-51. [Medline].

  29. Lin HY, Lin SP, Chen YJ, et al. Clinical characteristics and survival of trisomy 18 in a medical center in Taipei, 1988-2004. Am J Med Genet A. 2006 May 1. 140(9):945-51. [Medline].

  30. Kaneko Y, Kobayashi J, Yamamoto Y, Yoda H, Kanetaka Y, Nakajima Y. Intensive cardiac management in patients with trisomy 13 or trisomy 18. Am J Med Genet A. 2008 Jun 1. 146A(11):1372-80. [Medline].

  31. Kaneko Y, Kobayashi J, Achiwa I, Yoda H, Tsuchiya K, Nakajima Y. Cardiac Surgery in Patients with Trisomy 18. Pediatr Cardiol. 2009 Apr 2. [Medline].

  32. Kosho T, Nakamura T, Kawame H, Baba A, Tamura M, Fukushima Y. Neonatal management of trisomy 18: clinical details of 24 patients receiving intensive treatment. Am J Med Genet A. 2006 May 1. 140(9):937-44. [Medline].

  33. McGraw MP, Perlman JM. Attitudes of neonatologists toward delivery room management of confirmed trisomy 18: potential factors influencing a changing dynamic. Pediatrics. 2008 Jun. 121(6):1106-10. [Medline].

  34. Starr LJ, Sanmann JN, Olney AH, Wandoloski M, Sanger WG, Coulter DW. Occurrence of nephroblastomatosis with dup(18)(q11.2-q23) implicates trisomy 18 tumor screening protocol in select patients with 18q duplication. Am J Med Genet A. 2014 Apr. 164A(4):1079-82. [Medline].

  35. Nakai Y, Asano M, Nomura N, Matsumae H, Mishima A. Effectiveness of cardiac surgery in patients with trisomy 18: a single-institutional experience. Cardiol Young. 2016 Jan 28. 1-6. [Medline].

  36. [Guideline] Cunniff C. Prenatal screening and diagnosis for pediatricians. Pediatrics. 2004 Sep. 114(3):889-94. [Medline].

  37. Bronsteen R, Lee W, Vettraino IM, et al. Second-trimester sonography and trisomy 18. J Ultrasound Med. 2004 Feb. 23(2):233-40. [Medline].

  38. Carey JC. Introductory comments - special section: Prader-Willi syndrome. Am J Med Genet A. 2007 Mar 1. 143(5):413-4. [Medline].

  39. Chen CP. Aplasia and duplication of the thumb and facial clefts associated with fetal trisomy 18. Am J Med Genet A. 2006 May 1. 140(9):960-3. [Medline].

  40. Chen H. Trisomy 18 syndrome. Atlas of Genetic Diagnosis and Counseling. 2nd ed. New York Dordrecht Heidelberg London:Springer: Humana Press; 2012. 3: 2069-2080.

  41. Moyano D, Huggon IC, Allan LD. Fetal echocardiography in trisomy 18. Arch Dis Child Fetal Neonatal Ed. 2005 Nov. 90(6):F520-2. [Medline].

  42. Niedrist D, Riegel M, Achermann J, Schinzel A. Survival with trisomy 18--data from Switzerland. Am J Med Genet A. 2006 May 1. 140(9):952-9. [Medline].

Note the microphthalmia, micrognathia/retrognathia, microstomia, low-set/malformed ears, short sternum, and abnormally clenched fingers in an infant with trisomy 18 (Edwards syndrome).
This photo depicts the elongated skull, prominent occiput, low-set ear, micrognathia/retrognathia, short neck, and characteristic finger-grasping pattern in an infant with trisomy 18 (Edwards syndrome).
Note the characteristic clenched hand of trisomy 18 (Edwards syndrome) with the index finger overriding the middle finger and the fifth finger overriding the fourth finger.
This photo demonstrates a G-banded karyotype showing 47,XY,+18.
Note the rocker-bottom foot with a prominent calcaneus in an infant with trisomy 18 (Edwards syndrome).
This photo shows the hands of a fetus with trisomy 18 (Edwards syndrome). Note that hands typically present with overlapping digits, in which the second and fifth fingers override the third and fourth fingers, respectively. The overall posturing of the wrists and fingers in this fetus is suggestive of contractures.
All material on this website is protected by copyright, Copyright © 1994-2016 by WebMD LLC. This website also contains material copyrighted by 3rd parties.