Partial Trisomy 13

Luca’s diagnosis of Partial Trisomy 13 (PT13) is extremely rare! While the typical human has two chromosomes, an individual with a chromosomal disorder has an extra chromosome (full or partial) present.  With Trisomy 13, this extra chromosome causes severe intellectual disability and physical problems.

There are 4 variations of Trisomy 13:

• Full Trisomy 13 – Trisomy 13, also called Patau syndrome, is a chromosomal condition that occurs in approximately 1 in 10,000 live-born babies (it is more common than this, but most babies with Trisomy 13 miscarry during the pregnancy).  Most babies who are born with this condition pass away shortly after birth or within the first year of life, however, some can live longer.  This is the most common type of Trisomy 13
• Translocation Trisomy 13 – This type of Trisomy 13 occurs when mom or dad carry what is called a balanced translocation involving chromosome 13.  They are healthy and well but there is an increased chance with each pregnancy for the baby to have translocation Trisomy 13, which is 3 copies of chromosome 13, just in a different arrangement. The characteristics of translocation Trisomy 13 are the same as full Trisomy 13.
• Mosaic Trisomy 13– In this situation, only some of the cells (not all) in the body have an extra chromosome 13. mosaic Trisomy 13 may be less severe than full Trisomy 13.
• Partial Trisomy 13– This can occur if mom or dad carries a rearrangement of their chromosomes that involves chromosome 13. In this situation, the baby may have extra genetic information from part of chromosome 13 but not all of chromosome 13 as seen in full Trisomy 13.

Both Mosaic Trisomy 13 and Partial Trisomy 13 may be mild or severe, depending on how many and which cells have the extra chromosome.  In Luca’s case, he has a very small extra piece of chromosome 13 that attached to this 21st chromosome. Out of all four variations, I feel blessed that Luca only has a partial. His body will determine how he handles it has he grows, but at this he will have the opportunity to show us who he is meant to be!

Symptoms:

Trisomy 13 is associated with severe intellectual disability and physical abnormalities in many parts of the body. People with this condition often have congenital heart defects, brain or spinal cord abnormalities, very small or poorly developed eyes (microphthalmia), extra fingers and/or toes (polydactyly), cleft lip or palate, and decreased muscle tone (hypotonia). Many infants with trisomy 13 fail to grow and gain weight at the expected rate (failure to thrive); have severe feeding difficulties; and episodes in which there is temporary cessation of spontaneous breathing (apnea).

Other features of Trisomy 13 may include:

• Close-set eyes
• Hernias: umbilical hernia, inguinal hernia
• A hole, split, or cleft in the iris of the eye (coloboma)
• Low-set ears
• Scalp defects such as missing skin
• Seizures
• Single palmar crease
• Skeletal (limb) abnormalities
• Small head (microcephaly)
• Small lower jaw (micrognathia)
• Undescended testicle (cryptorchidism)
• Clenched hands

Luca has dealt with the following symptoms:  Polydactyly hands and feet, undescended testes, cleft lip, decreased muscle tone, hydronephrosis, mild hearing loss and seizures.

There is not one child like Luca in the world. Each person with PT13 has a different breakpoint for their extra piece of their 13th chromosome, a different size and a different place that this extra piece attaches to. While the geneticists can guess how the body will tolerate this extra piece, they really can’t be certain since all of these factors make a huge difference. I have connected with several families with children with PT13 through UNIQUE and there is a very HUGE difference between all of the children. When Luca was first diagnosed, we were desperate for answers and I reached out to anyone that I could to try to get a better understanding as well as to see what Luca’a future may look like. I quickly learned that each child is indeed unique and there was no way for my compare. Some seemed to have less severe issues than Luca while others seemed much more severe. There is a very broad range and in the end, I just can’t compare Luca to anyone else. He is his own person and this blog is hid journey!