What is Patau Syndrome (Trisomy 13)?

Patau Syndrome is a chromosomal disorder caused by the presence of an extra chromosome 13 in a person’s cells. Instead of the typical 46 chromosomes, affected individuals have 47 chromosomes.

  • Incidence: About 1 in 10,000–16,000 live births
  • Cause: Nondisjunction during the formation of reproductive cells, leading to an embryo with three copies of chromosome 13
  • Variants:
    • Full Trisomy 13 – extra chromosome present in every cell (most severe)
    • Mosaic Trisomy 13 – extra chromosome present in some cells (milder symptoms)
    • Partial Trisomy 13 – only part of chromosome 13 is duplicated

Key Characteristics

  • Cleft lip and/or cleft palate
  • Small head size (microcephaly)
  • Structural brain abnormalities (holoprosencephaly)
  • Severe facial dysmorphisms (low-set ears, small eyes)
  • Polydactyly (extra fingers or toes)
  • Heart defects
  • Kidney malformations

Symptoms and Health Concerns

Physical

  • Severe growth restriction before and after birth
  • Feeding difficulties due to poor muscle tone and structural defects
  • Abnormal genitalia in some cases

Neurological

  • Severe intellectual disability
  • Seizures
  • Poor muscle tone (hypotonia) or abnormal stiffness

Medical Risks

  • Very high mortality rate; most infants do not survive beyond the first weeks or months
  • Multiple organ defects affecting heart, brain, and kidneys
  • High risk of recurrent infections in survivors

Diagnosis

Prenatal

  • Screening tests: NIPT (Non-Invasive Prenatal Testing), first-trimester ultrasound (detecting structural abnormalities)
  • Diagnostic tests: Amniocentesis or CVS to confirm extra chromosome 13

Postnatal

  • Physical examination for characteristic features
  • Karyotype analysis to confirm diagnosis

Prevention & Risk Reduction

Patau Syndrome cannot be prevented naturally. However, Preimplantation Genetic Testing for Aneuploidy (PGT-A) during IVF can detect embryos with normal chromosome 13, helping to avoid transferring embryos with Trisomy 13.

Management

  • Supportive care for feeding and breathing problems
  • Surgery for cleft lip/palate or heart defects in selected cases
  • Palliative care for severe cases
  • Early developmental support for survivors with milder forms