Also called Trisomy 21, Down syndrome is a congenital genetic disorder marked by developmental delays, mental retardation, and other abnormalities. The severity of the condition varies from one patient to another; hence the associated disabilities also tend to vary between patients, from moderate to extreme.
Down syndrome is caused due to presence of an additional copy of chromosome 21 in some or all cells in the body. Babies born to women over 35 years old are more vulnerable to developing the condition. The incidence rate of Down syndrome is 1 in 850 newborns.
Down syndrome is the most common form of genetic disorder linked to learning problems in children. A better understanding of the condition as well as early diagnosis and subsequent interventions have led to betterment in the overall quality of life of the patients, both as children and as adults.
Symptoms of Down syndrome
The signs and symptoms of Down syndrome vary from one affected child to another as per the severity of the condition. A few common symptoms are listed below:
- Unusual facial features: Children with Down syndrome may have distinctive facial characteristics such as:
- The head may be smaller than normal
- The eyes may curve or slant upwards. Such ocular features are/seem abnormal according to the ethnicity of the child. Children may find it difficult to focus their eyes due to the structural ocular defects.
- The overall structure of the face may appear flattened.
- Abnormally shaped ears. This can cause hearing problems.
- A bulging or protruding tongue.
- Physical defects: They include:
- The fingers are shorter than normal
- The neck is shorter than usual
- Presence of broad and short hands. The palms may feature just a single crease.
- Muscle tone may be weak or impaired
- Excessive flexibility of the body
- Other defects: They are as follows:
- Delays in development, including severe delays in achievement of developmental milestones like sitting upright, walking, and crawling, etc.
- The overall growth in children with Down syndrome occurs gradually over a period of time. Hence, they are shorter than other healthy children of similar age. However, they grow up into adults of average height.
- Some form of mental retardation, ranging from mild to moderate, may be observed in some Down syndrome patients.
- There is a high risk towards development of varied health issues such as gastrointestinal conditions, leukemia, heart problems, and respiratory difficulties, etc.
What causes Down Syndrome?
Down syndrome is caused when chromosome 21 experiences irregular cell division. 23 pairs of chromosomes occur in the cells of the human body. One copy of each chromosome is passed to the child from the father, while the other copy is inherited from the mother.
Abnormal cell division in chromosome 21 can occur in 3 ways and each of these 3 ways result in the addition of extra genetic material to the chromosome. This is what leads to the formation of unique facial characteristics, developmental delays, mental problems, and other disabilities associated with Down syndrome. The three types of Down syndrome linked chromosome 21 defects are listed below:
- Trisomy 21 type of Down syndrome: In this, the affected child will have 3 copies of chromosome 21 in all the cells of the body. The genetic mutation or erroneous cell division occurs at the time of sperm and/or egg creation. Over 89 percent of Down syndrome patients suffer from this form of the condition.
- Mosaic form of Down syndrome: In this, chromosome 21 will feature an extra copy only in some cells of the body. Associated genetic mutation occurs at the time of fertilization.
- Translocated form of Down syndrome: In this, a section of chromosome 21 translocates or attaches to some other chromosome. It means that patients will have only 2 copies of chromosome 21, but other chromosomes may feature a part of chromosome 21 joined to them. This type of Down syndrome is rare. It can occur before or after conception.
Currently, there is no known method to correct genetic defects. Hence, there is no cure for Down syndrome. Treatment involves management and alleviation of symptoms, early intervention programs, and increased awareness about the condition, especially by the parents.
- Early intervention programs can help impart motor, language, self-help, and social skills in the child with Down syndrome. It is a vital step towards overcoming the effects of developmental problems and other abnormalities as well as inculcating self-reliance.
- Pregnant women can go for full integrated testing to check for the presence of Down syndrome in the unborn child. This can help prepare themselves better for future care and support of the child.
- Ultrasound and blood tests can be carried out in between the 11th and 13th weeks of pregnancy.
- Expectant mothers who think that the baby may be at high risk to Down syndrome may go for percutaneous umbilical blood sampling, amniocentesis, chorionic villus sampling, and other relevant diagnostic tests.
Down syndrome life expectancy
Over the years the life expectancy of Down syndrome patients has increased dramatically due to advances in the medical sciences. Down syndrome patients used to live for only nine years before, but now they can live without problems for nearly 60 years.
Most deaths associated with Down syndrome occur in the uterus or during the first year after birth. A newborn may die within some weeks or months after delivery, often due to cardiac defects and a host of other health complications. After Down syndrome children successfully cross the first year of life, their life expectancy increases by 11 years or more. It is therefore important for parents to pay special attention to the child during the first year.
A majority of deaths associated with Down syndrome occur due to leukemia and cardiac problems. Advances in the field of medicines and medical therapies have resulted in effective treatments for different kinds of cardiac defects and leukemia, thereby increasing the life expectancy of Down syndrome patients. Proper identification of underlying medical problems, early intervention programs, and significant parental support, care, and understanding are key to increasing the lifespan of the patients.