Saturday, March 3, 2012

Trisomy 13 - Patau Syndrome

I'm continuing my look at Trisomy disorders by profiling Patau Syndrome, Trisomy 13. Though discovered in 1657, the genetic cause was determined by Dr. Klaus Patau in 1960. As with all instances of trisomy, Patau Syndrome occurs when three copies of chromosome 13 are in some or all of an individual's cells. There are three forms of Trisomy 13:
  1. Partial trisomy involves the presence of part of an extra copy of chromosome 13 in the cells.
  2. Trisomy 13 mosaicism occurs when some of the cells have an extra chromosome 13.
  3. Trisomy 13 has a full extra copy of chromosome 13 in all of the cells.
In some rare cases the extra genetic material may translocate and attach to a different chromosome. Trisomy 13 is fairly uncommon, occurring in approximately 1 in 10,000-21,700 newborns. Due to the severity of genetic damage (remember the lower the number of the chromosome the more genetic information it contains) the condition sometimes results in miscarriage or stillbirth (around 8% of prenatal diagnoses). Further, 80% of babies born with Trisomy 13 will not survive beyond their first year. However, those who do survive birth and early infancy can live to adulthood. Children with partial or mosaic Patau have an even more hopeful outlook. Therefore it saddens me to know that up to 64% of babies diagnosed prenatally with Trisomy 13 are eliminated by elective abortion.

Each child with Trisomy 13 will have different needs depending on what symptoms are evident. Some common issues include:
  • Cleft lip or palate
  • Close set eyes - may even fuse into one structure
  • Extra fingers or toes
  • Seizures
  • Limb abnormalities
  • Small head
  • Small lower jaw
  • Congenital heart defects - placement toward right side of chest, septal or ductal defects
  • Holoprosencephaly - the forebrain doesn't divide properly
Often these physical challenges are detected first by ultrasound. MRI or CT scans may also be used. Chromosome studies are used to specify the type (Patau) and sub-type (partial, mosaic, or full) of Trisomy.

Caring for an infant with Trisomy 13 often involves addressing breathing issues like apnea, feeding problems, heart failure, seizures, and challenges with seeing and hearing. It is essential for families to find support as they walk through caring for a child with Trisomy 13. One well-known organization to contact is SOFT. Another is Hope for Trisomy 13 and 18.

How fitting that March is Trisomy Awareness month!


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