Causes of down syndrome

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Down syndrome is a genetic disorder where the baby is born with extra load of 21st chromosome. It retards the physical and mental developments of the baby. It is a serious medical condition with severe disabilities leading to reduced life expectancy.


It is mainly caused by the partial separation of chromosome 21. In all, there are 46 chromosomes in a fully developed normal cell with each parent contributing 23 chromosomes.
When there is improper separation of the 21 chromosomes, it produces three copies instead of two with the extra chromosome causing problems in the course of the physical and mental development of the baby.


There are basically three forms of Down syndrome:

Trisomy 21: it is the commonest type of Down syndrome; it is a condition when there is an extra copy of chromosome 21 in every cell.

Mosaicism: it is a condition when a child has an extra chromosome in some but not all of their cells at birth.

Translocation: it is a condition when one of the 46 chromosomes in the child has an extra part of chromosome 21 attached to it.


Risk factors

Maternal age is one of the predisposing factors to having a baby with Down syndrome. Mothers in their mid 30s and above have higher risk.
Having family history of Down syndrome also exposed one to risk of Down syndrome birth.
People with genetic translocation


Short neck
Flat facial characteristics
Small head and ears
Mental Disability
Bulging tongue
Upward slant eyes
Poor muscle tone
Retarded growth
Hearing impairment
Blur vision
Congenital heart defects
Delayed growth of teeth
Chronic constipation
Sleep apnea
Minimal thyroid function

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Screening and Diagnosis

It is advisable for all pregnant women especially those who have higher risk of having baby with Down syndrome to present for prenatal care.

In the 15th week of pregnancy, amniocentesis can be done to check possible symptoms of Down syndrome. Also, ultrasound examination and blood tests are useful in diagnosing Down syndrome in the fetus.

During the second trimester, particularly from 15 to 20 weeks, an ultrasound and quadruple marker screen (QMS) test are ordered to display Down syndrome and other possible defects in the brain and spinal cord.

Chorionic villus sampling (CVS) involves getting cells from the placenta to have detailed information on the fetal chromosomes usally done in the ninth and 14th week of pregnancy.

Percutaneous umbilical blood sampling involves the use of blood from the umbilical cord and evaluating it for chromosomal defects usually carried out in after 18th week of pregnancy.

At birth, the doctor can have a physical examination of the baby and order for a karyotype blood test to establish Down syndrome.


No specific cure exists for Down syndrome. There is need to support the baby emotionally and physically in the course of his/her existence. The services of counselor and therapists will assist the child to learn and develop the social, sensory and motion skills as well as language and cognitive skills.

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