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Information About Conditions

Trisomies

A trisomy is a term for a genetic condition in which there are three chromosomes instead of the usual pair.

Trisomy 21 / Down Syndrome:

Trisomy 21, more commonly known as Down Syndrome, is a condition caused by an extra copy of chromosome 21. Unfortunately, miscarriage occurs in about 30% of pregnancies with Down Syndrome. Those children born with Down Syndrome will need extra medical care depending on the child’s specific health problems. Most children with Down Syndrome have intellectual disabilities that range from mild to moderate. Early intervention has proven to be essential in enabling individuals with Down Syndrome to lead healthy and productive lives. For more information or support, please see our resources page.

Trisomy 18 / Edwards Syndrome:

Trisomy 18, or Edwards Syndrome, is caused when a baby has three copies of chromosome 18, instead of two. Unfortunately, pregnancies with Edwards Syndrome are at high risk of miscarriage and most babies born with Edwards Syndrome die within the first few weeks of life while less than 10% live beyond one year. Infants with Edwards Syndrome have severe intellectual disabilities and birth defects typically involving the heart, brain, and kidneys, and external abnormalities such as cleft lip/palate, small head, club feet, underdeveloped digits, and small jaw.

Trisomy 13 / Patau Syndrome:

Trisomy 13, or Patau Syndrome, is caused when a baby has three copies of chromosome 13, instead of two. Unfortunately, pregnancies diagnosed with Patau Syndrome are at high risk for miscarriage or stillbirth, and most babies born with Patau Syndrome will not survive beyond the first weeks of life. Babies with Patau Syndrome may have heart defects, brain or spinal cord problems, extra fingers and/or toes, an opening in the lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate), and weak muscle tone. Many babies have birth defects of other organs as well.

Deletion Syndromes

Deletion syndromes are defined as a group of clinically recognisable disorders characterised by a small deletion of a chromosomal segment. The size and position of the deletion determine which clinical features are manifested and how severe they are.

5p / Cri-du-Chat:

Also known as 5P deletion sydnrome, babies typically exhibit small head size, low birth weight, decreased muscle tone. and have moderate to severe intellectual disability. Feeding and/or breathing difficulties are also common.

1p36:

Babies born with 1p36 deletion syndrome typically have weak muscle tone, heart and other organ defects. Most will display developmental problems and varying degrees of intellectual disability.

2q33.1:

Babies born with 2q33.1 will typically experience delayed growth and exhibit behavioural developmental problems. Severe feeding difficulties are common and the incidence of cleft palate is also high.

Sex Chromosomal Aneuploidy

Each cell in your body contains 46 chromosomes arranged in 23 pairs. One of these chromosome pairs is known as the sex chromosomes because this pair of chromosomes determines our sex. Sex chromosome abnormalities occur when there are extra, missing, or altered sex chromosomes present.

XXY / Klinefelter Syndrome:

Klinefelter’s syndrome is a genetic condition that only affects males. Affected males have an extra X chromosome.Males with Klinefelter’s syndrome have small testes which do not produce enough of the male hormone testosterone before birth and during puberty. This lack of testosterone means that during puberty, the normal male sexual characteristics do not develop fully. There is reduced facial and pubic hair, and some breast tissue often develops. The lack of testosterone is also responsible for other symptoms, including infertility.

X / Turner Syndrome:

Turner syndrome is caused by a completely or partially missing X sex chromosome in females. Females with Turner syndrome often have a wide range of symptoms and some distinctive characteristics. Two that occur in almost all cases of Turner syndrome are:
-being shorter than average
-underdeveloped ovaries (female reproductive organs), resulting in a lack of monthly periods and infertility.

XXX / Triple X:

Triple X syndrome, also called trisomy X is characterized by the presence of an additional X chromosome in each of a female’s cells. The symptoms and physical features associated with trisomy X vary greatly from one person to another. Some females may have no symptoms (asymptomatic) or very mild symptoms and may go undiagnosed. Other women may have a wide variety of different abnormalities.
Triple X syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills (such as sitting and walking), weak muscle tone (hypotonia), and behavioral and emotional difficulties are also possible, but these characteristics vary widely among affected girls and women. Seizures or kidney abnormalities occur in about 10 percent of affected females.

XYY / Jacob Syndrome:

XYY, sometime called Jacob syndrome, affects only males and is caused by the presence of an extra Y chromosome.
Affected individuals are usually very tall. Many experience severe acne during adolescence. Additional symptoms may include learning disabilities and behavioural problems such as impulsivity.