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Trisomy 13

(Patau Syndrome; Trisomy D)

By

Nina N. Powell-Hamilton

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Last full review/revision Jul 2020
CLICK HERE FOR THE PROFESSONAL VERSION
Topic Resources

Trisomy 13 is a chromosomal disorder caused by an extra chromosome 13 that results in severe intellectual disability and physical abnormalities.

  • Trisomy 13 is caused by an extra chromosome 13.

  • Infants are typically small and often have major brain, eye, face, and heart defects.

  • Tests can be done before or after birth to confirm the diagnosis.

  • There is no treatment available for trisomy 13.

An extra chromosome, making three of the same chromosome (instead of the normal two), is called trisomy. Children who have trisomy 13 have a third chromosome 13. Trisomy 13 occurs in about 1 out of 10,000 live births. The extra chromosome usually comes from the mother. Mothers who are over age 35 are at increased risk of having a child with trisomy 13.

Symptoms of Trisomy 13

In the womb, affected fetuses are typically not very active. The amount of amniotic fluid may be too much or too little.

Physical abnormalities

At birth, newborns tend to be small Small-for-Gestational-Age (SGA) Newborn A newborn who weighs less than 90% of newborns of the same gestational age at birth (below the 10th percentile) is considered small for gestational age. Newborns may be small because their parents... read more . The brain typically does not develop properly, and these children have many facial abnormalities such as cleft lip and cleft palate Cleft Lip and Cleft Palate The most common birth defects of the skull and face are cleft lip and cleft palate, affecting about 2 of every 1,000 babies. Cleft lip is a separation of the upper lip, usually just below the... read more Cleft Lip and Cleft Palate , small eyes, defects of the iris (the colored area of the eye), and underdeveloped retinas (the clear, light-sensitive structures at the back of the eyes). The ears are abnormally shaped and usually low-set. Defects in the scalp and openings in the skin are common. Loose folds of skin often are present over the back of the neck. Newborns commonly have a single crease in the palm, extra fingers and toes (polydactyly Finger and Toe Defects The fingers and toes may be abnormally formed, incompletely formed, or missing at birth. Birth defects of the fingers and toes can occur while a baby is developing in the womb. For example,... read more Finger and Toe Defects ), and poorly developed fingernails.

Cleft Lip and Cleft Palate: Defects of the Face

Cleft Lip and Cleft Palate: Defects of the Face

Other abnormalities

Diagnosis of Trisomy 13

  • Before birth, ultrasonography of the fetus or blood tests of the mother

  • Chorionic villus sampling, amniocentesis, or both

  • After birth, the appearance of the infant and blood tests of the infant

Before birth, trisomy 13 may be suspected based on findings detected during an ultrasound of the fetus. Doctors also can do a test to find deoxyribonucleic acid (DNA) from the fetus in the mother's blood and use this DNA to determine an increased risk of trisomy 13. This test is called noninvasive prenatal screening (NIPS) or cell-free fetal DNA testing. If doctors suspect trisomy 13 based on these tests, they often confirm the diagnosis using chorionic villus sampling Chorionic Villus Sampling Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more , amniocentesis Amniocentesis Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more , or both.

After birth, the infant's physical appearance may suggest the diagnosis of trisomy 13. To confirm the diagnosis, the infant's chromosomes are analyzed using a blood test.

Prognosis and Treatment of Trisomy 13

  • Support for the family

There is no specific treatment available for trisomy 13. Most children (80%) are so severely affected that they die before 1 month of age, and less than 10% survive longer than 1 year. Family members should seek support.

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