What is Trisomy 13?
Understanding the Basics
Trisomy 13, also known as Patau syndrome, is a genetic disorder caused by the presence of an extra 13th chromosome. Normally, humans have 23 pairs of chromosomes, totaling 46. In individuals with Trisomy 13, there are three copies of chromosome 13 instead of the usual two, resulting in 47 chromosomes. This extra genetic material disrupts normal development, leading to various physical and intellectual challenges.
Causes
Trisomy 13 typically occurs as a random event during the formation of reproductive cells (eggs and sperm). The error, known as nondisjunction, results in a reproductive cell with an extra chromosome. When this cell combines with a normal cell from the other parent during fertilization, the embryo ends up with an extra chromosome 13.
Types of Trisomy 13
Full Trisomy 13: Every cell in the body has an extra 13th chromosome. This is the most common form.
Mosaic Trisomy 13: Some cells have the extra chromosome, while others do not. This can result in a less severe form of the disorder.
Partial Trisomy 13: Only a part of the extra chromosome 13 is present in the cells. This form is very rare and can cause a wide range of symptoms depending on which part of the chromosome is extra.
Symptoms
Trisomy 13 is associated with a range of specific physical features. It is unlikely that a baby would be born with ALL the complications, but more common they would have several indicators from the list that would point to a Trisomy 13 diagnosis:
Microcephaly (small head)
Micropthalmia (small eyes)
Other eye problems such as missing eye or retinal defect
Holoproscencephaly (failure of the forebrain to divide completely)
Cleft lip and/or palate
Variations in the development of the ears
Variations in the palm
Extra digits on hands or feet
Variations in foot development
Trisomy 13 is also associated with some specific medical complications
Approximately 80% of children will have a heart condition
Kidney defects
Feeding difficulties
Apnoea or epilepsy
Omphalocele
Diagnosis
Trisomy 13 can be diagnosed before birth through prenatal testing, including:
Ultrasound: May reveal physical abnormalities associated with Trisomy 13.
Non-Invasive Prenatal Testing (NIPT): A blood test offered to women who have a higher chance result following previous screening tests. This is a non-diagnostic test.
Amniocentesis: Involves taking a sample of amniotic fluid to examine the chromosomes.
Chorionic Villus Sampling (CVS): Involves taking a sample of placental tissue to analyze the chromosomes.
After birth, diagnosis is confirmed through a chromosomal analysis called a karyotype, which can identify the extra chromosome.
Prognosis
The prognosis for children with Trisomy 13 is generally poor. Many infants with this condition are stillborn or die within the first few weeks or months of life. However, some children can survive longer with medical intervention and supportive care.
All children are unique and will react differently, with some being affected more severely than others. It is important to note that a diagnosis of Trisomy 13 does not mean your child will not survive. To find out more about children from our community who are living with Trisomy 13, visit our family stories here: https://www.soft.org.uk/living-with-trisomy
Support and Management
There is no cure for Trisomy 13, and treatment focuses on managing symptoms and providing supportive care. This may include:
Medical Management: Addressing heart defects, feeding issues, and other medical complications.
Therapies: Physical, occupational, and speech therapies to help with developmental delays.
Palliative Care: For children with severe symptoms, palliative care can provide comfort and improve quality of life.
Support for Families
Receiving a diagnosis of Trisomy 13 can be overwhelming for families. It's crucial to seek support from healthcare providers, genetic counselors, and support groups. Connecting with other families who have children with Trisomy 13 can provide valuable emotional support and practical advice.