Trisomy 13
Posted on: October 30, 2008
Illustrations 
Polydactyly – an infant’s hand 
Syndactyly
Alternative names Return to top
Definition Return to top
Trisomy 13 is a syndrome associated with the presence of a third (extra) number 13 chromosome.
Causes, incidence, and risk factors Return to top
Trisomy 13 occurs in about 1 out of every 5,000 live births. It is a syndrome with multiple abnormalities, many of which are not compatible with life. More than 80% of children with trisomy 13 die in the first month.
Trisomy 13 is associated with multiple abnormalities, including defects of the brain that lead to seizures, apnea, deafness, and eye abnormalities.
The eyes are small with defects in the iris (coloboma ). Most infants have a cleft lip and cleft palate, and low-set ears. Congenital heart disease is present in approximately 80% of affected infants. Hernias and genital abnormalities are common.
Symptoms Return to top
- Mental retardation, severe
- Seizures
- Small head (microcephaly)
- Scalp defects (absent skin)
- Small eyes (microphthalmia)
- Cleft lip and/or palate
- Eyes close set (hypotelorism) — eyes may actually fuse together into one
- Iris defects (coloboma)
- Pinna abnormalities and low set ears
- Simian crease
- Extra digits (polydactyly)
- Hernias: umbilical hernia, inguinal hernia
- Undescended testicle (cryptorchidism)
- Hypotonia
- Micrognathia
- Skeletal (limb) abnormalities
Signs and tests Return to top
The infant may have a single umbilical artery at birth. There are often signs of congenital heart disease:
- Ventricular septal defect (VSD)
- Atrial septal defect (ASD)
- Patent ductus arteriosus (PDA)
- Abnormal placement of the heart (dextroversion — the heart is placed toward the right side of the chest instead of the left)
Gastrointestinal x-rays or ultrasound may reveal abnormal rotation of the internal organs.
MRI or CT scans of the head may reveal a structural abnormality of the brain, called holoprosencephaly, where the 2 cerebral hemispheres are fused.
Chromosome studies show trisomy 13, partial trisomy, trisomy 13 mosaic, or translocation.
Treatment Return to top
Because of the severity of congenital defects, life-sustaining procedures are generally not attempted.
Support Groups Return to top
Support Organization for Trisomy 18, 13 and Related Disorders (SOFT) — www.trisomy.org
Expectations (prognosis) Return to top Extremely short survival time is expected. Rarely, affected persons survive to adulthood.
Complications Return to top
Complications begin almost immediately. They include breathing difficulty or lack of breathing (apnea), deafness, vision problems, feeding problems, seizures, heart failure, and others.
Calling your health care provider Return to top
Call for an appointment with your health care provider if you have had a child with Trisomy 13, and you plan to have another child.
Prevention Return to top
Trisomy 13 can be diagnosed prenatally by amniocentesis with chromosome studies of the amniotic cells. Trisomy 13 mosaicism and partial trisomy 13 also occur. Parents of infants with trisomy 13 caused by a translocation should have genetic testing and counseling, which may help them prevent recurrence.
Update Date: 4/20/2005
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Trisomy 13 Facts
Trisomy 13 syndrome is a disorder of human chromosomes which occurs in approximately 1 in 10,000 live born infants. Trisomy 13 is due to the presence of an extra #13 chromosome. Approximately 80% of infants with Trisomy 13 syndrome will have a full trisomy while the remainder will have a trisomy due to a rearrangement called a translocation or have mosaicism (two different cell lines).
Infants born with Trisomy 13 have a recognizable pattern of physical features that often allow the health professional to make the diagnosis of the syndrome. Notable physical birth defects and sometimes, anatomic changes of internal organs are present. Findings of significance include small head size (microcephaly); small eyes (microphthalmia) or sometimes absent eye or faulty development of the retina. Cleft lip or cleft palate or both occur in about 60% of children. In addition, there are a number of less medically significant physical findings that are helpful in diagnosis. These include variations of ear shape, changes on the palm of the hand, and extra fingers and toes. Changes in foot development, including changes to the heel, the so-called rocker bottom foot, can occur.
Heart Defects
About 80% of children with Trisomy 13 will have a congenital heart defect. These can include: ventricular septal defect – an opening between the lower chambers of the heart which prevents the heart from pumping blood correctly (a heart murmur is generally heard from this finding); atrial septal defect – an opening between the two upper chambers of the heart making it difficult for the heart to pump sufficient oxygen rich blood to body tissues (a heart murmur is often heard); patent ductus arteriosis – a defect involving the lack of closure of the channel that usually closes near the time of birth; dextrocardia – location of the heart on the right side of the chest; on occasion more medically serious heart defects can occur in Trisomy 13.
Synonyms: Trisomy 13
Patau Syndrome
Trisomy 13-15
D Trisomy Syndrome
(these last two terms are usually not used at the present time)
Medical Problems
The major implications of Trisomy 13 involve a predisposition to congenital malformations (birth defects) mentioned above, an increased mortality in infancy, and a developmental disability in older children. In addition, older infants can have visual difficulties because of the findings mentioned above and a hearing loss. The increased mortality is related to difficulties with breathing due to either interrupted breathing (apnea), or problems of lung development. In addition, gastroesophageal reflux and feeding problems can occur and predispose to aspiration adding to this risk. Usually the heart defects are not serious enough to be a major health threat in the newborn period.
Important and Common Birth Defects in Trisomy 13
Omphalocele Holoprosencephaly 60% (an anatomic defect of the brain involving failure of the forebrain to divide properly)
Kidney Defects 30%Skin defects of the scalp 20%
Common Disorders in infants and young children with Trisomy 13
feeding difficulties
gastroesophageal reflux
slow post natal growth
apnea seizures
hypertension
kidney defects
developmental disabilities
scoliosis
Routine Follow-up care of infants with Trimsomy 13
Routine child care/anticipatory guidance
Cardiac evaluation
Eye evaluation
Hearing test Referral for Infant pre-school/early childhood intervention program
Referral for Infant pre-school/early intervention program
Ongoing support
Scoliosis check through childhood
Routine immunizations for immunization including chicken pox
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Trisomy Disorders 
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