EGL Genetics Blog

Trisomies: More Common Than You Think

Posted by Danyella Davis on Mar 15, 2017 3:00:00 PM

Chromosomal abnormalities are common causes of birth defects that can affect neurological functions and various parts of the human body. Accounting for nearly 20% of all infant deaths, birth defects are the leading cause of infant mortality, according to the Centers for Disease Control And Prevention. Mother-Hand-New-Born-Small-Cute-Feet-Child-Baby-1908307.jpg

Three of the most common newborn aneuplodies are trisomies 13, 18, and 21. About one in 5,000 babies is born with trisomy 18, one in 16,000 is born with trisomy 13 and one in 700 babies is born with trisomy 21, the most frequently occurring chromosomal abnormality. Although women of all ages may have a child with trisomy 13, 18, or 21, the risk  increases with advanced maternal age

March was named National Trisomy Awareness Month to increase awareness of trisomy conditions and to provide resources and support to the trisomy community, as families are often ladened with uncertainty, anxiety, and sometimes, loss.

According to the National Institute of Healthtrisomy conditions typically result from a random abnormal cellular division that occurs very early in development and are not passed from one generation to the next.

Of the commonly detected trisomies, 13, 18, and 21 cause a range of severe health problems, learning difficulties, and physical development delays.

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Trisomy 21 or Down syndrome 

Children with Down syndrome experiencelow growth, developmental delays, limited cognitive skills, and heart abnormalities. Other birth defects may consist of hearing, vision loss, and a number of health conditions, including feeding and swallowing delays. Physical characteristics may include depressed nasal bridge, low-set ears, mouth-breathing and brushfield spots and bilateral epicanthal folds. Visit the Down syndrome consortium  to access research and support resources.



Trisomy 18 or Edwards syndrome 

Children with Edwards syndrome experience severe birth defects and health problems involving nearly every organ system. Babies with trisomy 18 often have intrauterine growth retardation and a low birth weight. Additional trisomy 18 features include an abnormally small-shaped head, clenched fists, and wide-spaced eyes. Due to several life-threatening medical problems, many babies with trisomy 18 die before birth or within the first month. Only about 50% of babies born survive beyond the first six to nine days of life and only about 12% of babies born survive the first year of life. For support and patient resources, visit the NIH Resource.


DNA transfer.png Though there is no proven cause or genetic predisposition  for trisomy 18, the NIH reports partial trisomy 18 can be  inherited. An unaffected person may carry a rearrangement  of genetic material between chromosome 18 and another  chromosome, which is called a balanced translocation.  Though they don't  have any clinical signs of trisomy 18,  individuals who carry this type of balanced translocation are    at an increased risk of having children with Edwards syndrome.




Trisomy 13 or Patau syndrome 

Children with Patau syndrome are typically born with heart defects, brain or spinal cord abnormalities and server intellectual disabilities. It is not uncommon for babies to have extra fingers, toes, or a cleft lip or palate. Due to several life-threatening medical problems, many infants with trisomy 13 die within the first days or weeks of life. According to the NIH, only 5-10% of children live beyond the first year. For additional support and patient resources, visit Support Organization for Trisomy 18, 13 and Related Disorders (SOFT).


If you're interested in additional information and genetic testing for Trisomy 13, 18, or 21, visit EGL Genetics website. For additional resources, visit The Trisomy 18 Foundation. 



Participate in Trisomy Awareness Month by registering for this month's webinar!

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Register Today



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