Patau Syndrome (Trisomy 13)

A genetic disorder caused by an extra copy of chromosome 13

Table of Contents

Quick Facts

  • Type: Chromosomal (genetic) disorder
  • Cause: Extra copy of chromosome 13
  • Present: From birth (congenital)
  • Diagnosis: Genetic testing, ultrasound

Overview

Patau syndrome, also called trisomy 13, is a chromosomal disorder in which a baby is born with three copies of chromosome 13 instead of the usual two. This extra genetic material disrupts normal development, leading to multiple serious birth defects affecting the brain, heart, face, and other organs.

Patau syndrome is one of the most severe of the common autosomal trisomies. Many pregnancies affected by it end in miscarriage or stillbirth, and most infants born with full trisomy 13 have life-limiting complications. Care focuses on comfort, supporting the family, and managing individual medical problems. Rarely, children with milder (mosaic or partial) forms live longer.

Symptoms

Patau syndrome affects many parts of the body, and features vary from child to child. Common findings include:

  • Severe intellectual disability and delayed development
  • Structural brain abnormalities, sometimes with a single central eye structure (holoprosencephaly)
  • Cleft lip and cleft palate
  • Small or absent eyes, or eyes set close together
  • Extra fingers or toes (polydactyly)
  • Congenital heart defects
  • Low birth weight and poor feeding
  • Scalp defects and abnormalities of the hands and feet

Because several organ systems are involved, breathing difficulties, seizures, and feeding problems are common in the newborn period.

Causes

Patau syndrome is caused by having an extra full or partial copy of chromosome 13 in the body's cells. There are three main forms:

  • Full trisomy 13: An extra chromosome 13 is present in every cell, usually due to a random error when the egg or sperm forms. This is the most common and most severe form.
  • Translocation trisomy 13: Extra chromosome 13 material is attached to another chromosome. This can be inherited from a parent who carries a balanced rearrangement.
  • Mosaic trisomy 13: Only some cells have the extra chromosome, which can lead to milder features.

In most cases the extra chromosome arises by chance and is not caused by anything the parents did before or during pregnancy.

Risk Factors

  • Advanced maternal age increases the chance of trisomy from random chromosome errors
  • A parent who carries a balanced chromosome 13 translocation
  • A previous pregnancy affected by a chromosomal disorder

Most cases occur in families with no prior history, and there is usually no preventable cause.

Diagnosis

Patau syndrome may be suspected before or after birth.

  • Prenatal screening: Cell-free DNA (NIPT) blood testing and detailed ultrasound can raise suspicion of trisomy 13.
  • Diagnostic testing in pregnancy: Chorionic villus sampling or amniocentesis can confirm the diagnosis by examining the baby's chromosomes (karyotype).
  • After birth: A blood test for a chromosome analysis confirms the diagnosis when features are recognized in the newborn.

Genetic counseling helps families understand the type of trisomy and any chance of it happening again.

Treatment

There is no cure for Patau syndrome, and care is individualized to the child's needs. Decisions are made together with the family and medical team.

  • Comfort and supportive care: Keeping the baby comfortable, feeding support, and family-centered care are central, especially given the severity of the condition.
  • Treating specific problems: Some heart defects, cleft lip, or other issues may be addressed surgically in selected children, depending on overall health and goals of care.
  • Seizure and feeding management: Medications and feeding support help manage symptoms.
  • Family support: Palliative care teams, counseling, and support groups help families through difficult decisions.

Prevention

Patau syndrome usually cannot be prevented because it most often results from a random chromosome error. However, families can take steps to understand their risk:

  • Genetic counseling before or during pregnancy, especially after a previous affected pregnancy or when a parent carries a translocation
  • Prenatal screening and diagnostic testing to provide information and prepare for care

When to See a Doctor

If prenatal screening suggests a chromosomal disorder, your obstetric and genetics team can explain the next steps and testing options. After birth, a baby with multiple birth defects, feeding difficulty, or breathing problems needs prompt evaluation by a pediatric team. Seek emergency care for an infant who is struggling to breathe, turning blue, or having a seizure.

Genetic counseling is recommended for any family affected by trisomy 13 who is considering future pregnancies.

Related Topics

Down Syndrome

Trisomy 21, the most common chromosomal disorder.

 Chromosomal Abnormalities

Disorders caused by changes in chromosome number or structure.

 Congenital Heart Defect

Heart problems present from birth, common in trisomy 13.

 Congenital Malformation Syndrome

Patterns of birth defects affecting multiple organs.

Frequently Asked Questions

What is the difference between Patau syndrome and Down syndrome?

Both are chromosomal disorders caused by an extra chromosome, but Patau syndrome involves chromosome 13 and Down syndrome involves chromosome 21. Patau syndrome is much rarer and generally far more severe, with multiple serious birth defects.

Is Patau syndrome inherited?

Most cases happen by chance from a random chromosome error and are not inherited. A small number are caused by a translocation that a parent carries, which can be passed on. Genetic testing and counseling can clarify which type is involved.

Can Patau syndrome be detected before birth?

Yes. Prenatal screening such as cell-free DNA testing and ultrasound can suggest trisomy 13, and diagnostic tests like amniocentesis or chorionic villus sampling can confirm it by examining the baby's chromosomes.

What is the outlook for a baby with Patau syndrome?

Full trisomy 13 is a life-limiting condition, and many affected infants do not survive the first weeks or months because of severe heart, brain, and breathing problems. Children with mosaic or partial forms may have milder features and live longer. Care is guided by the family and medical team.

Did anything the parents do cause Patau syndrome?

No. The extra chromosome almost always results from a random error when the egg or sperm forms, which is not caused by anything the parents did before or during pregnancy.

Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with any questions about a medical condition.

References

  1. MedlinePlus, U.S. National Library of Medicine. Trisomy 13.
  2. National Organization for Rare Disorders (NORD). Trisomy 13 Syndrome.
  3. Centers for Disease Control and Prevention (CDC). Birth Defects.
  4. Genetics Home Reference / MedlinePlus Genetics. Trisomy 13.