Pediatrics · Trisomy 13

Physical Features and Anatomical Differences

At a Glance

Trisomy 13 can affect several developing body systems, including the brain, heart, face, kidneys, abdominal wall, and spine. Children can have very different combinations of findings, so imaging and care decisions should reflect each child’s stability and the family’s goals.

While Trisomy 13 follows a characteristic pattern, it is a condition of great variety. No two children with Trisomy 13 are exactly alike. These anatomical differences occur because the extra genetic material changes how the body’s systems are “blueprinted” during early fetal development ^[1]^[2].

It is important to remember that not every child will have every feature listed below, and medical imaging (like a brain MRI or echocardiogram) should be individualized based on your child’s stability and your family’s overall goals of care ^[3]^[4].

Brain Development and the Holoprosencephaly Spectrum

One of the most significant ways Trisomy 13 can affect development is through holoprosencephaly (HPE). In early pregnancy, the brain typically divides into two distinct halves (hemispheres). HPE occurs when this division is incomplete ^[5]. This exists on a spectrum:

Alobar HPE: The most severe form, where the brain does not divide at all, resulting in a single central cavity ^[6].
Semilobar and Lobar HPE: These are less severe forms where the brain halves are partially separated ^[7].

Research indicates that between 24% and 45% of children with Trisomy 13 have some form of HPE ^[8]. Because the brain controls many midline facial features, the severity of HPE often relates to the severity of facial differences, though this relationship is not exact enough to predict brain function perfectly ^[9].

Congenital Heart Defects

Heart defects are a primary driver of a child’s health and stability in Trisomy 13 ^[10]. While population estimates suggest heart defects are present in 57% to 76% of cases, studies looking specifically at infants admitted to neonatal intensive care units (NICUs) report rates as high as 86% to 92% ^[1]^[11].

The most frequent heart findings include:

Septal Defects: “Holes” in the walls separating the heart’s chambers, often called Atrial Septal Defects (ASD) or Ventricular Septal Defects (VSD) ^[10].
Patent Ductus Arteriosus (PDA): A blood vessel that should close shortly after birth remains open ^[12].
Complex Anatomy: Some children may have more complex arrangements, such as a single-ventricle physiology, where the heart effectively has only one pumping chamber ^[10].

Facial and Physical Features

Trisomy 13 can result in visible physical differences. While the appearance of these features may not be inherently painful, they can cause significant functional distress or require painful corrective procedures:

Orofacial Clefts: Approximately 45% of infants have a cleft lip or cleft palate ^[1]. This can cause immediate distress regarding feeding, making it difficult for the baby to suck or swallow safely without aspiration.
Polydactyly: About 44% to 67% of children are born with an extra finger or toe ^[1]^[13].
Eye Anomalies: Around 30% to 53% of children have eye differences, such as microphthalmia (abnormally small eyes) or anophthalmia (absence of eyes), which can lead to functional vision loss and discomfort ^[1]^[13].

Other Body Systems

The extra genetic material can affect almost any part of the body. Other potential findings include:

Kidneys: Prenatal imaging estimates that up to 71% of fetuses with Trisomy 13 have renal (kidney) anomalies, such as cysts or structural differences ^[13].
Abdominal Wall: Some babies are born with an omphalocele, where abdominal organs develop in a sac outside the body near the belly button ^[14].
Neural Tube: Less commonly, there may be differences in the development of the spine, such as spina bifida ^[15].

Common questions in this guide

What brain differences are associated with Trisomy 13?

Trisomy 13 can be associated with holoprosencephaly, a condition in which the developing brain does not fully separate into two halves. It ranges from severe alobar holoprosencephaly to less severe semilobar or lobar forms, and the extent of facial differences does not perfectly predict brain function.

What heart problems can a baby with Trisomy 13 have?

Heart defects are common in Trisomy 13 and may include holes between the heart chambers, an open ductus arteriosus, or more complex single-ventricle anatomy. An echocardiogram helps the care team understand the specific heart structure and how it may affect the child’s stability.

Which physical features are common in Trisomy 13?

Possible findings include cleft lip or palate, extra fingers or toes, and eye differences such as unusually small or absent eyes. These features vary widely, and not every child has all of them. Clefts may make feeding and safe swallowing difficult, while eye differences can affect vision or cause discomfort.

Can Trisomy 13 affect the kidneys and other organs?

Yes. Trisomy 13 may be associated with kidney abnormalities, an omphalocele in which abdominal organs develop in a sac outside the body, and less commonly spinal differences such as spina bifida. Imaging and monitoring are individualized based on the child’s medical stability and the family’s goals of care.

Do physical features predict how a child with Trisomy 13 will develop?

Not completely. Trisomy 13 affects children differently, and the severity of a facial or brain finding cannot reliably predict brain function or the child’s overall course. The care team can combine examination and individualized imaging with the child’s day-to-day needs.

What specialists can help evaluate Trisomy 13 anatomical differences?

A pediatric cardiologist can explain heart findings, and a pediatric neurologist can help interpret brain-related differences. Other clinicians may be involved depending on feeding, vision, kidney, or abdominal findings, with imaging chosen according to the child’s stability and the family’s goals.

Get notified when new evidence is published on Trisomy 13 syndrome.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.

References (15)

1
Congenital anomalies associated with trisomy 18 or trisomy 13: A registry-based study in 16 European countries, 2000-2011.
Springett A, Wellesley D, Greenlees R, et al.
American journal of medical genetics. Part A 2015; (167A(12)):3062-9 doi:10.1002/ajmg.a.37355.
PMID: 26347425
2
Prenatal diagnosis of low-level mosaicism for trisomy 13 at amniocentesis associated with a favorable outcome.
Chen CP, Chern SR, Wu PS, et al.
Taiwanese journal of obstetrics & gynecology 2017; (56(6)):840-842 doi:10.1016/j.tjog.2017.10.025.
PMID: 29241931
3
A Longitudinal Case Study of Renal Cyst Progression and Regression in Trisomy 13.
Yamabe F, Shindo T, Haneda K, et al.
Clinical case reports 2025; (13(9)):e70851 doi:10.1002/ccr3.70851.
PMID: 40919399
4
Low-level mosaic trisomy 13 at amniocentesis associated with a favorable outcome in a pregnancy.
Chen CP, Chern SR, Wu FT, et al.
Taiwanese journal of obstetrics & gynecology 2020; (59(6)):935-937 doi:10.1016/j.tjog.2020.09.022.
PMID: 33218415
5
Holoprosencephaly spectrum: an up-to-date overview of classification, genetics and neuroimaging.
Gomez GD, Corrêa DG, Trapp B, et al.
Japanese journal of radiology 2025; (43(1)):13-31 doi:10.1007/s11604-024-01655-8.
PMID: 39259418
6
Sonography of fetal holoprosencephaly: a guide to recognize the lesser varieties.
Montaguti E, Cariello L, Brunelli E, et al.
The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians 2022; (35(25)):9717-9723 doi:10.1080/14767058.2022.2050900.
PMID: 35272544
7
Lobar holoprosencephaly with associated meningocele: A rare case report of a 25-year-old patient with multiple seizures.
Barman P, Mishra GV, Murugan G, et al.
Radiology case reports 2025; (20(4)):2004-2008 doi:10.1016/j.radcr.2025.01.029.
PMID: 39963386
8
Holoprosencephaly in Patau Syndrome.
Schlosser AS, Costa GJC, Silva HSD, et al.
Revista paulista de pediatria : orgao oficial da Sociedade de Pediatria de Sao Paulo 2023; (41()):e2022027 doi:10.1590/1984-0462/2023/41/2022027.
PMID: 36921175
9
Holoprosencephaly: a survey of the entity, with embryology and fetal imaging.
Winter TC, Kennedy AM, Woodward PJ
Radiographics : a review publication of the Radiological Society of North America, Inc 2015; (35(1)):275-90 doi:10.1148/rg.351140040.
PMID: 25590404
10
Contemporary Trends in Cardiac Surgical Care for Trisomy 13 and 18 Patients Admitted to Hospitals in the United States.
Greenberg JW, Kulshrestha K, Ramineni A, et al.
The Journal of pediatrics 2024; (268()):113955 doi:10.1016/j.jpeds.2024.113955.
PMID: 38340889
11
Clinical courses of children with trisomy 13 receiving intensive neonatal and pediatric treatment.
Nishi E, Takasugi M, Kawamura R, et al.
American journal of medical genetics. Part A 2018; (176(9)):1941-1949 doi:10.1002/ajmg.a.40350.
PMID: 30152146
12
Mortality and Resource Use Following Cardiac Interventions in Children with Trisomy 13 and Trisomy 18 and Congenital Heart Disease.
Domingo L, Carey JC, Eckhauser A, et al.
Pediatric cardiology 2019; (40(2)):349-356 doi:10.1007/s00246-018-2001-x.
PMID: 30291384
13
Duplicated distal phalanx of thumb or hallux in trisomy 13: A recurrent feature in a series of 42 fetuses.
Létard P, Guimiot F, Dupont C, et al.
American journal of medical genetics. Part A 2018; (176(11)):2325-2330 doi:10.1002/ajmg.a.40505.
PMID: 30328679
14
Phenotypic and cytogenetic variability of patau syndrome in Morocco.
Hammou HA, Sennaoui M, Bouzid F, et al.
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PMID: 38974285
15
The Co-Existence of Patent Omphalomesenteric Duct and Omphalocele in Patau's Syndrome in Saudi Arabia: A Case Report.
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PMID: 38125687

This page is for informational purposes only and does not constitute medical advice. Your child’s care team can explain which Trisomy 13 findings are present and how they may affect evaluation and care.