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.

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.

• Trisomy 13
• Patau Syndrome
• Trisomy 13-15
• D Trisomy Syndrome

 (these last two terms are usually not used at the present time)

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 10%
• 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 Trisomy 13

• Routine child care/anticipatory guidance
• Cardiac evaluation
• Eye evaluation
• Hearing test
• Referral for Infant pre-school/ early intervention program
• Ongoing Support
• Scoliosis check through childhood
• Routine immunization including chicken pox

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