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Trisomy 13


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Trisomy 13 (Patau syndrome) is the third most common autosomal abnormality among live births after Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18). Most trisomy 13 cases result from total trisomy 13 (Buyse, 1990). A small proportion of trisomy 13 cases result from mosaicism and translocation (Forrester and Merz, 1999; Carothers et al., 1999; Buyse, 1990). Some trisomy 13 fetuses detected in mid-trimester do not survive to term (Hook et al., 1989).

Maternal serum screening has not been found to differ significantly between pregnancies affected with trisomy 13 and normal pregnancies (Saller and Canick, 1999; Canick and Saller, 1993). Over the last several decades, prenatal ultrasonography can detect a variety of structural anomalies frequently associated with trisomy 13 (Abramsky and Chapple, 1993; Vintzileos et al., 1987). Prenatal ultrasonography and definitive diagnosis by karyotyping through such procedures as amniocentesis and chorionic villus sampling have allowed trisomy 13 to be identified in utero. Studies from various birth defects surveillance systems have found that, in regions where elective termination is allowed, prenatal diagnosis and elective termination reduce the prevalence of trisomy 13 (Chaabouni et al., 2001; De Vigan et al., 2001; Forrester and Merz, 1999; Carothers et al., 1999; Forrester et al., 1998; Riley et al., 1998; Wyllie et al., 1994; Abramsky and Chapple, 1993; Pradat et al., 1991).



Trisomy 13 involving total trisomy 13 results from nondisjunction, usually in formation of the eggs or sperm, where one of the gametes ends up with an extra chromosome 13. Nondisjunction may occur in the first meiotic stage (MI) or the second meiotic stage (MII). The extra chromosome 13 is of maternal origin in 88 percent of the cases and of paternal origin in 12 percent of the cases. Among trisomy 13 cases of maternal origin, almost all result from nondisjunction in MI (Nicolaidis and Petersen, 1998; Zaragoza et al., 1994).



Risk of trisomy 13 is well known to increase with increasing maternal age (Forrester and Merz, 1999; Carothers et al., 1999; Goldstein and Nielsen, 1988; Schreinemachers et al., 1982). Trisomy 13 risk has been associated with increasing paternal age (Baty et al., 1994); however, once maternal age is taken into consideration the association with paternal age tends to disappear. Higher trisomy 13 risk has been associated with increasing parity (Monteleone et al., 1981); however, this observation may be confounded by maternal age.

Race/ethnicity has not been reported to influence trisomy 13 rates (Buyse, 1990). One study found that, of the four racial/ethnic groups examined (white, Far East Asian, Pacific Islander, Filipino), trisomy 13 risk was highest for Far East Asians and lowest for Pacific Islanders (Forrester and Merz, 1999). However, the differences in risk appeared to be due to differences in maternal age distribution among the racial/ethnic groups. Another investigation observed no significant difference in risk of Patau syndrome in infants born to Vietnamese women compared with infants born to non-Hispanic white women in California (Shaw et al., 2002).

Geographic area may influence trisomy 13 risk. One study reported higher trisomy 13 rates among urban residents (Forrester and Merz, 1999). However, this high risk among urban residents seemed to be due to differences in maternal age distribution between urban and rural areas.

One investigation has reported a secular trend for trisomy 13, with the prevalence of the aneuploidy increasing over time. However, the increase in trisomy 13 prevalence over time was considered due to increasing numbers of births to older women and increasing prenatal diagnosis of affected pregnancies (Forrester and Merz, 1999). There does not appear to be seasonal variation in trisomy 13 rates (Videbech and Nielsen, 1984).

Infant sex influences the risk for trisomy 13. Males are more likely than females to have the aneuploidy (Forrester and Merz, 1999; Carothers et al., 1999; Riley et al., 1998; Goldstein and Nielsen, 1988; Monteleone et al., 1981). Trisomy 13 is also associated with lower birth weight, prematurity, and intrauterine growth retardation but not plurality (Rasmussen et al., 2001; Riley et al., 1998; Mili et al., 1991).

The recurrence risk for trisomy 13 has been reported to be approximately 1% (Baty et al., 1994).



No lifestyle or environmental factors have been definitively reported to affect trisomy 13 risk.

One study has reported that women who had infants or fetuses with trisomy 13 were not more likely to have mutation in the methylenetetrahydrofolate reductase (MTHFR) gene or the methionine synthase reductase (MTRR) gene (Hassold et al., 2001).


  • Abramsky L, Chapple J. Room for improvement? Detecting autosomal trisomies without serum screening. Public Health 1993;107:349-354.
  • Baty BJ, Blackburn BL, Carey JC. Natural history of trisomy 18 and trisomy 13. I. Growth, physical assessment, medical histories, survival, and recurrence risk. Am J Med Genet 1994;49:175-188.
  • Buyse ML, editor-in-chief. Birth Defect Encyclopedia. Cambridge, Massachusetts: Blackwell Scientific Publications, 1990.
  • Canick JA, Saller DN. Maternal serum screening for aneuploidy and open fetal defects. Obstet Gynecol Clin North Am 1993;20:443-454.
  • Carothers AD, Boyd E, Lowther G, Ellis PM, Couzin DA, Faed MJ, Robb A. Trends in prenataldiagnosis of Down syndrome and other autosomal trisomies in Scotland 1990 and 1994, with associated cytogenetic and epidemiological findings. Genet Epidemiol 1999;16:179-190.
  • Chaabouni H, Chaabouni M, Maazoul F, M'Rad R, Jemaa LB, Smaoui N, Terras K, Kammoun H, Belghith N, Ridene H, Oueslati B, Zouari F. Prenatal diagnosis of chromosome disorders in Tunisian population. Ann Genet 2001;44:99-104.
  • De Vigan C, Baena N, Cariati E, Clementi M, Stoll C; EUROSCAN Working Group. Contribution of ultrasonographic examination to the prenatal detection of chromosomal abnormalities in 19 centres across Europe. Ann Genet 2001;44:209-217.
  • Forrester MB, Merz RD. Trisomies 13 and 18: Prenatal diagnosis and epidemiologic studies in Hawaii, 1986-1997. Genet Test 1999;3:335-340.
  • Forrester MB, Merz RD, Yoon PW. Impact of prenatal diagnosis and elective termination on the prevalence of selected birth defects in Hawaii. Am J Epidemiol 1998;148:1206-1211.
  • Goldstein H, Nielsen KG. Rates and survival of individuals with trisomy 13 and 18. Clin Genet 1988;34:366-372.
  • Hassold TJ, Burrage LC, Chan ER, Judis LM, Schwartz S, James SJ, Jacobs PA, Thomas NS. Maternal folate polymorphisms and the etiology of human nondisjunction. Am J Hum Genet 2001;69:434-439.
  • Hook EB, Topol BB, Cross PK. The natural history of cytogenetically abnormal fetuses detected at midtrimester amniocentesis which are not terminated electively: New data and estimates of the excess and relative risk of late fetal death associated with 47,+21 and some other abnormal karyotypes. Am J Hum Genet 1989;45:855-861.
  • Khoury MJ, Erickson JD, Cordero JF, McCarthy BJ. Congenital malformations and intrauterine growth retardation: a population study. Pediatrics 1988;82:83-90.
  • Mili F, Edmonds LD, Khoury MJ, McClearn AB. Prevalence of birth defects among low-birth- weight infants. A population study. Am J Dis Child 1991;145:1313-1318.
  • Monteleone PL, Anderson R, Chen S-C, Nouri S, Monteleone JA, Taysi K. A demographic study of trisomy 13. Ped Res 1981;15:565.
  • Nicolaidis P, Petersen MB. Origin and mechanisms of non-disjunction in human autosomal trisomies. Hum Reprod 1998;13:313-319.
  • Rasmussen SA, Moore CA, Paulozzi LJ, Rhodenhiser EP. Risk for birth defects among premature infants: A population-based study. J Pediatr 2001;138:668-673.
  • Riley MM, Halliday JL, Lumley JM. Congenital malformations in Victoria, Australia, 1983-95: an overview of infant characteristics. J Paediatr Child Health 1998;34:233-240.
  • Saller DN, Canick JA, Blitzer MG, Palomaki GE, Schwartz S, Blakemore KJ, Haddow JE. Second-trimester maternal serum analyte levels associated with fetal trisomy 13. Prenat Diagn 1999;19:813-816
  • Schreinemachers DM, Cross PK, Hook EB. Rates of 47,+21, 47,+18, 47,+13 and other chromosome abnormalities in about 20,000 prenatal studies compared to estimated rates in livebirths. Hum Genet 1982;61:318-324.
  • Shaw GM, Carmichael SL, Nelson V. Congenital malformations in offspring of Vietnamese women in California, 1985-97. Teratology 2002a;65:121-124.
  • Videbech P, Nielsen J. Chromosome abnormalities and season of birth. Hum Genet 1984;65:221- 231.
  • Vintzileos AM, Campbell WA, Nochimson DJ, Weinbaum PJ. Antenatal evaluation and management of ultrasonically detected fetal anomalies. Obstet Gynecol 1987;69:640-660.
  • Wyllie JP, Wright MJ, Bern J. Natural history of trisomy 13. Arch Dis Child 1994;71:343-345.
  • Zaragoza MV, Jacobs PA, James RS, Rogan P, Sherman S, Hassold T. Nondisjunction of human acrocentric chromosomes: studies of 432 trisomic fetuses and liveborns. Hum Genet 1994;94:411-417.


Please Note: The primary purpose of this report is to provide background necessary for conducting cluster investigations. It summarizes literature about risk factors associated with this defect. The strengths and limitations of each reference were not critically examined prior to inclusion in this report. Consumers and professionals using this information are advised to consult the references given for more in-depth information. 

This report is for information purposes only and is not intended to diagnose, cure, mitigate, treat, or prevent disease or other conditions and is not intended to provide a determination or assessment of the state of health. Individuals affected by this condition should consult their physician and when appropriate, seek genetic counseling.

For more information:

Birth Defects Epidemiology and Surveillance
Texas Department of State Health Services
1100 W. 49th Street, Austin, Texas 78756
512-776-7232 Fax 512-776-7330

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Last updated February 10, 2012