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LIFE

What Non-Invasive Prenatal Testing screens for

PUBLISHED : Monday, 19 January, 2015, 6:02am
UPDATED : Monday, 19 January, 2015, 6:02am

At present, NIPT provides information about specific fetal aneuploidies, or chromosomal abnormalities. According to the US National Coalition for Health Professional Education in Genetics, all laboratories offering NIPT report on Down's syndrome and Edwards syndrome.

Others may also provide information about Patau syndrome or some sex chromosome abnormalities and microdeletions.

Down's syndrome (trisomy 21)

Down's syndrome is the most common trisomy and the single most common cause of intellectual disability. It can be associated with a number of physical problems, including congenital heart defects, hearing impairment and eye disorders.

Maternal age is a risk factor for the condition. By age 35, a woman's risk of conceiving a child with Down's syndrome is about one in 385. By age 45, the risk is about one in 30.

Edwards syndrome (trisomy 18)

Edwards syndrome is the second most common trisomy seen at birth. It can cause severe physical, mental, and organ defects, such as cleft palate, club foot, kidney defects and congenital heart defects. Many babies with this condition don't survive beyond a few months. Incidence is one in 6,000 live births.

Patau syndrome (trisomy 13)

Patau syndrome is the third most common trisomy seen at birth. It can cause severe physical, mental and organ defects, such as cleft palate, club foot, facial defects and congenital heart defects. Many babies with this condition don't survive beyond a few months. Incidence is between one in 5,000 and one in 29,000 live births.

Sex chromosome aneuploidies

Sex chromosome aneuploidies is a common group of disorders characterised by an abnormal number of X or Y chromosomes. These include Turner syndrome (X0), Klinefelter syndrome (XXY), Triple X (XXX) and Jacobs syndrome (XYY).

Many individuals with these disorders are not diagnosed. Most have normal intelligence, although some have learning disabilities and/or psychological issues.

Microdeletions

These tiny missing pieces of DNA at the sub-chromosomal level can have serious health implications. Some NIPT tests screen for the most common and severe microdeletion syndromes, such as 22q11.2 deletion syndrome (also known as DiGeorge syndrome), 1p36 deletion, Angelman, Cri-du-chat and Prader-Willi syndromes.

These five microdeletions have a combined incidence of about one out of every 1,000 births.