Down’s Syndrome – Causes, Risk Factors and Symptoms
Down's Syndrome is a birth defect caused by an extra 21st chromosome that should not be there. The condition was named after the person who first identified it, Dr. John Langdon Down. Down's Syndrome is the most commonplace birth defect found in United States children. It afflicts an estimated one of 800 infants.
However, it is quite survivable: Around 85 percent of babies with the defect survive a year, with 50 percent living more than 50 years. Currently, over 350,000 people in the United States have Down's Syndrome.
Causes of Down's Syndrome:
Three kinds of irregular cell division can cause Down's Syndrome--all of these involve chromosome 21. These variations include:
- Trisomy 21. This is the cause in more than 90 percent of the instances of Down's Syndrome. The sperm and egg unite and form a fertilized egg, but rather than two, three chromosomes 21 are then present. The cells divide and the extra chromosome is then found in every cell.
- Mosaic Trisomy 21. This form represents less than two percent of Down's Syndrome cases. The difference between this form and Trisomy 21 is that the extra chromosome is only found in some of the cells, not all of them.
- Translocation Trisomy 21. This one represents three or four percent of all Down's Syndrome cases. In this variety, a portion of the chromosome 21 gets attached to another one (either the 13th, 14th or 15th), either at conception or sometimes before. The carrier of the extra chromosome has 45 chromosomes rather than 46. However, they have the genetic material of the person who has 46. The carrier has the extra genetic material, but just a single chromosome 21. The carrier never exhibits the symptoms of Down's, since his genetic material is the right amount.
If a mother has a Down's child who suffers the affliction because of Translocation Trisomy 21, future pregnancies have an increased risk of producing Down's children. The reason is because at least one parent is likely a balanced carrier. If the dad is the carrier, there is a three percent chance of producing a Down's child. If the mother is the carrier, it's a 12 percent chance.
Risk Factors for Down's Syndrome
There are certain factors you should know that makes one set of parents more likely to produce a child with Down's Syndrome than another couple. These factors include:
- Age of the mother. The chance of chromosomes not dividing as they're supposed to divide increases as a woman's eggs age. This gives her a higher risk of producing a Down's child.
- A previous Down's child. There is a slightly higher risk of having a second child with Down's if a prior child had the defect (about a one percent increased chance).
- A parent carrier. If one of the parents carries the genetic tendency for Down's, there is an increased chance of the baby having the birth defect. In this case, you should seek prenatal screening / counseling for the matter. A screening test or diagnostic test will help sort through things.
A screening test is conducted by the medical staff to help identify what the possibility of having a Down's child is. They are not 100 percent reliable, but they do help show you the chance of a baby having the defect. It's an estimate of the odds, in essence. Diagnostic tests, on the other hand, attempt to show if an unborn child has the defect. These are expensive and a bit on the risky side.
Some of the screening tests available include an ultrasound or blood tests. Diagnostic tests are usually conducted if the screening test shows a high risk for Down's. These tests include Amniocentesis, Chorionic villus sampling (or "CSV"), and Percutaneous Umbilical Blood Sampling (or "PUBS"). Amniocentesis is performed sometime after the 15th week of pregnancy, CVS between the ninth and 14th, and PUBS after the 18th week.
If you wait until after the child is born, the doctor will base his diagnosis on the appearance of the child. If it appears that some of the usual Down's characteristics are present, he will request a chromosomal karyotype to be done on the baby. If this indicates the presence of an extra chromosome 21, he will declare it Down's Syndrome.
Symptoms of Down's
Here are the most common symptoms of Down's Syndrome that might prompt you to seek out a diagnosis from a doctor.
- Short neck
- Flat face
- Eyes slant unnaturally upward
- Irregular ear shape
- Protruding tongue
- The palm of the child's hand has a very deep crease and short fingers
- The eye's iris has white spots
- Poor muscle tone
- Excessive flexibility
- Loose ligaments
- Hands and feet that seem strangely small
- Hearing problems
- Problems with intestines
- Celiac disease
- Thyroid dysfunctions
- Eye problems
- Skeletal problems
- Infectious diseases--more so than most children
- Dementia, somewhat akin to Alzheimer's.
While there is no cure for Down's Syndrome, it's important that you tell your doctor that you suspect Down's. There are ways that children benefit from developmental interventions and therapies. By assembling a team of competent doctors and therapists, you can put your child on the right track toward a life of productivity and much greater happiness.