Trisomy 21 (Down Syndrome), Trisomy 18 & Trisomy 13

Our cells usually have 23 pairs of chromosomes. Trisomy is the word used to describe the presence of an extra chromosome in the cells. Trisomies are named based on which chromosome has the extra copy, so a person with trisomy 21 has an extra copy of chromosome 21. The Harmony test looks for trisomy 21 (Down  syndrome), trisomy 18 and trisomy 13.

  • The cause of 22q deletion syndrome

    A microdeletion is the absence of a small piece of chromosome and is named by the area of the chromosome that is absent. The Harmony test looks for 22q11.2 microdeletion, the most common genetic cause of intellectual disability and heart defects after Down syndrome.1 While it can be inherited from a parent, most babies with 22q11.2 microdeletion are the first in their family to be diagnosed.3 Some people with 22q11.2 microdeletion have very subtle features that are not noticed until after childhood, while others have birth defects that are seen during a prenatal ultrasound.4,5 22q11.2 microdeletion is the cause of genetic syndromes such as velocardiofacial syndrome and DiGeorge syndrome.

For more detailed information about 22q11.2 microdeletion including pregnancy management, health care guidelines, advocacy and support for families:

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