How is Trisomy 13 Syndrome / Patau Syndrome diagnosed?

Trisomy 13 Syndrome, also known as Patau Syndrome, is a genetic disorder caused by the presence of an extra copy of chromosome 13 in the cells of an individual. This condition is characterized by a range of physical and intellectual disabilities, and it is typically diagnosed through a combination of prenatal testing and postnatal clinical evaluations.

Prenatal Diagnosis:

Prenatal screening tests can help identify the risk of Trisomy 13 Syndrome in a developing fetus. These tests include:

• Ultrasound: A routine ultrasound examination can reveal certain physical abnormalities associated with Trisomy 13, such as heart defects, brain malformations, cleft lip or palate, and extra fingers or toes.


• Maternal Serum Screening: Blood tests can measure the levels of certain substances in the mother's blood, which may indicate an increased risk of chromosomal abnormalities, including Trisomy 13.


• Non-Invasive Prenatal Testing (NIPT): This advanced screening test analyzes cell-free fetal DNA in the mother's blood to detect chromosomal abnormalities, including Trisomy 13, with high accuracy.


• Chorionic Villus Sampling (CVS): In this procedure, a small sample of placental tissue is extracted and analyzed to determine the chromosomal makeup of the fetus. CVS can detect Trisomy 13, but it carries a small risk of miscarriage.


• Amniocentesis: This procedure involves extracting a small amount of amniotic fluid surrounding the fetus and analyzing the fetal cells within it. Amniocentesis can provide a definitive diagnosis of Trisomy 13, but it also carries a small risk of miscarriage.

Postnatal Diagnosis:

If Trisomy 13 is not detected prenatally or if the diagnosis is uncertain, postnatal clinical evaluations can confirm the presence of the syndrome. The signs and symptoms that may prompt further testing include:

• Physical Features: Babies with Trisomy 13 often exhibit distinct physical characteristics, such as cleft lip or palate, small head size (microcephaly), low-set ears, small eyes (microphthalmia), and extra fingers or toes (polydactyly).


• Organ Abnormalities: Heart defects, brain malformations, kidney abnormalities, and other organ defects are common in individuals with Trisomy 13.


• Intellectual and Developmental Disabilities: Trisomy 13 can cause severe intellectual disability, developmental delays, and other neurological impairments.

Once Trisomy 13 is suspected, a healthcare professional may order further diagnostic tests, including:

• Karyotype Analysis: This test examines the chromosomes of an individual's cells to identify any abnormalities, including the presence of an extra copy of chromosome 13.


• Fluorescence In Situ Hybridization (FISH): FISH is a molecular cytogenetic technique that can specifically detect the presence of an extra chromosome 13.


• Genetic Testing: Various genetic tests, such as chromosomal microarray analysis or next-generation sequencing, can provide detailed information about the genetic makeup and potential genetic abnormalities associated with Trisomy 13.

It is important to note that while prenatal testing can provide an indication of the likelihood of Trisomy 13, a definitive diagnosis can only be made through postnatal testing. Genetic counseling is highly recommended for individuals and families affected by or at risk of Trisomy 13 Syndrome to understand the implications, available support, and management options.