What are the other Names for this Condition? (Also known as/Synonyms)

• Mosaic Trisomy 11 Syndrome
• Prenatal Trisomy 11 Mosaicism

What is Trisomy 11 Mosaicism? (Definition/Background Information)

• Trisomy 11 Mosaicism is a very rare chromosomal disorder, in which fetal cells in the amniotic fluid show a mixed population of cells with an extra copy of chromosome 11. The term trisomy indicates that there are 3 copies of chromosome 11 in some of the cells
• Among the reported cases, the gestation, delivery, and development of the baby following its birth are found to be normal. Hence, a treatment of the condition is not necessitated, and the outcomes are generally excellent

Who gets Trisomy 11 Mosaicism? (Age and Sex Distribution)

• Trisomy 11 Mosaicism is a rare chromosomal disorder, with very few cases reported
• Both males and females may be affected by Trisomy 11 Mosaicism
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Trisomy 11 Mosaicism? (Predisposing Factors)

Currently, no risk factors have been clearly identified for Trisomy 11 Mosaicism.

• No environmental and lifestyle (including dietary) factors are also implicated
• The syndrome is not caused by what the expectant mother does or does not do, either prior to or during pregnancy

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Trisomy 11 Mosaicism? (Etiology)

The cause of Trisomy 11 Mosaicism is not known at the present time.

• The condition may be the result of random errors in the chromosomes, either during the division of the egg or sperm in one of the parents, or during cell division after fertilization
• Mosaic Trisomy 11 Syndrome presents a duplication of chromosome 11 material in some of the fetal cells
• Since no evidence of Trisomy 11 Mosaicism was found in babies in whom the condition was diagnosed prenatally, it has been suggested that the cells showing the extra chromosome 11 during prenatal evaluation may be extra-embryonic in origin

It is important to note that a child’s development and future is not only influenced by the chromosome material duplicated/deleted and genes involved, but also by other factors such as one’s environment, involvement of other genes, and unique personality.

Additional (general) information on chromosomes, which is helpful in understanding the disorder:

Chromosomes are microscopic thread-like protein structures present in each cell nucleus that carry genetic information in the form of DNA (deoxyribonucleic acid). DNAs are nucleic acids that encodes the genetic information of any organisms; a basic unit of the DNA is termed a gene with a specific set of instructions and a defined function. Each chromosome is “X” shaped with a center, called the centromere, and two short arms (termed p arms) and two long arms (termed q arms).

Humans have 46 chromosomes in the cell nucleus, in 23 pairs, of which one pair is named the sex chromosome. In males, it is designated XY, for chromosome X and chromosome Y; while, in females, it is designated XX, for a pair of chromosome X. The other 22 pairs of chromosomes are numbered chromosome 1 through 22, approximately according to size (with chromosome 1 being the largest; chromosome 21 being the smallest) and are referred to as autosomes or somatic chromosomes. During conception, the embryo inherits one copy of each chromosome from each parent (i.e., mother and father). Any alteration in the chromosome numbers or structure, such as via addition or deletion of chromosomal material, can result in mild to severe genetic abnormalities that may manifest as birth defects, growth delays, and intellectual disabilities.

What are the Signs and Symptoms of Trisomy 11 Mosaicism?

• According to published literature, although Trisomy 11 Mosaicism was present in the fetal stages (in the womb), the babies were normal and healthy after birth
• No signs and symptoms of Trisomy 11 Mosaicism were evident in the development of prenatally diagnosed babies
• And, the babies developed normally after birth without any signs and symptoms of Trisomy 11 Mosaicism

How is Trisomy 11 Mosaicism Diagnosed?

Trisomy 11 Mosaicism is diagnosed on the basis of the following information:

• Complete physical examination and thorough medical history evaluation, including family medical history
• Laboratory tests, as needed
• Prenatal studies including abdominal ultrasonography: In some cases, a pregnancy ultrasound may reveal signs and symptoms that are suggestive of a chromosomal or developmental disorder. Following this, additional tests may be conducted, including:
  • Chorionic villus sampling (CVS)
  • Amniocentesis
• Karyotyping of the following:
• Fetal cells from amniotic fluid
• Fetal blood lymphocytes
• Fibroblasts from newborns
• Urinary epithelial cells from newborns

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Trisomy 11 Mosaicism?

No complications have so far been reported in children diagnosed with Trisomy 11 Mosaicism.

How is Trisomy 11 Mosaicism Treated?

• No treatment has been found to be necessary for Trisomy 11 Mosaicism due to the manifestation of no significant signs and symptoms. According to reports, the condition is apparently auto-corrected in the fetus
• If any signs and symptoms develop, then treatment may be given to manage the same and any complications that develop

How can Trisomy 11 Mosaicism be Prevented?

Trisomy 11 Mosaicism may not be preventable since many of these genetic disorders are diagnosed at or following the birth of the child. A majority of cases are sporadic occurrences, which means there is no family history of the condition.

• Prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

It is important to note that the chances of both the parents with normal chromosomes having another child with Mosaic Trisomy 11 Syndrome is highly unlikely. This may be confirmed via specialized prenatal testing and preimplantation genetic diagnosis (PGD), if needed. Prenatal tests may include chorionic villus sampling (CVS) and amniocentesis.

What is the Prognosis of Trisomy 11 Mosaicism? (Outcomes/Resolutions)

• The prognosis of Trisomy 11 Mosaicism is good in the cases reported so far
• Babies diagnosed with Trisomy 11 Mosaicism in the fetal stages have developed normally. In a vast majority of cases, no evidence of the condition was reported after the birth of the child

Additional and Relevant Useful Information for Trisomy 11 Mosaicism:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/