What is Down Syndrome?
Did you know there is at least one case of Down syndrome in every 700 pregnancies? Research also suggests that the older a mother, the more likely she is to give birth to a child with Down syndrome. However, there are several other factors that are also deemed responsible for giving rise to this disorder. Understandably, this turns out to be a vital topic that must be understood by every student of Biology.
Read along to find more about the Down syndrome symptoms, features, and types!
The Down syndrome definition describes it as a chromosomal disorder, wherein, an error in cell division leads to an extra copy of chromosomes in the body. This extra chromosome 21 tends to affect the physical and cognitive abilities of affected individuals.
Additionally, individuals with Down syndrome often run a higher risk of suffering from various health disorders. Notably, it is not a disease rather a term that best describes the features which arise due to it.
On that note, let us proceed to find types of Down syndrome and their differences.
Types of Down Syndrome
Typically, there are 3 types of Down syndrome –
Trisomy 21
It is the most common of the three types and accounts for almost 95% of the cases. It is mostly caused by the irregular separation of chromosome 21 during meiosis either in egg cells or sperm. When the fertilized egg develops, it transfers an extra copy of this chromosome to each cell in the body.
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Translocation
It accounts for 4% of the total cases. It must be noted that in this particular type, the extra chromosome is transferred to new cells differently.
It occurs only when a significant part of chromosome 21 breaks off amidst the replication process and gets attached to another chromosome. This leads to a cell with 46 chromosomes and a little extra chromosome 21.
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Mosaicism
This particular type accounts for as little as 1% of the total cases. Notably, in this form, the error in separation takes place right after the egg is fertilized.
The role of timing is the most noteworthy here. Also, the fact that not all cells have an extra chromosome makes the symptoms of mosaic Down syndrome less prominent.
Do It Yourself: Define Down syndrome and mention its types.
Down Syndrome Features
These are some Down syndrome features –
A. Physical Features
Small stature with a short neck
Flat nasal bridge
low muscle tone
Eyes slant upwards
Eyes have an additional fold on the upper eyelid
A large gap between the large and second toe
B. Cognitive Features
Intellectual disability ranges from mild to moderate level
Delay in learning to speak
Delay in motor skills
Problematic attention span
Other than these, individuals with Down syndrome are prone to health problems like – congenital heart defect, epilepsy, respiratory disorders, hearing difficulty, leukemia, Alzheimer’s, thyroid, etc.
One can diagnose this anomaly through a screening test and other prescribed diagnostic tests.
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Test Your Knowledge: Highlight the differences between the 3 types of Down syndrome.
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Management of Down Syndrome
There can be several efforts such as early childhood intervention, screening for common problems and medical treatment wherever indicated, a good family environment, and work-related training can improve the development of children with Down syndrome. Education and proper care have been known to improve the overall quality of life. A parent must accept the challenges and the reality that raising a child with Down syndrome is more work for parents than raising an unaffected child. Other than the above-mentioned steps, typical childhood vaccinations are recommended.
Health Screening
Health organizations have largely recommended screening those with Down syndrome for particular diseases so that the affected can be provided with adequate medical aid.
At birth, all children affected with Down syndrome are advised to get an electrocardiogram and ultrasound of the heart. In many cases, surgical intervention for the treatment of heart problems may be required (as early as three months of age). In adult patients, heart valve problems may occur and further ultrasound evaluation is essential in adolescents and those in early adulthood. As there is an elevated risk of testicular cancer, some doctors recommend yearly examination of testicles in male patients.
Cognitive Development in Down Syndrome
Hearing aids or other amplification devices have been found to be useful for language learning in those with hearing loss. Training and speech therapy is recommended to be started as early as possible (around nine months of age).
Enrollment in educational programs to assist learning and social interaction before reaching school age may be useful. Children of school-going age diagnosed with Down syndrome can benefit from inclusive education (whereby students of differing abilities are placed in classes with their peers of the same age), provided some adjustments are made to the curriculum to suit their individual needs. Evidence to support this, however, seems to be weak. In the United States, due to the Individuals with Disabilities Education Act of 1975, public schools are required to generally allow attendance by students with Down syndrome and create a more inclusive ethos for persons of disability.
Individuals with Down syndrome learn better through visual aids. There still may be persistent difficulty in children with down syndrome in creating sentence structure and grammar and face ability to speak clearly but early intervention can help with cognitive development. Motor skills can be enhanced through the use of physical therapy, speech and language therapy, and occupational therapy. Physical therapy primarily focuses on motor development and teaching children to interact with their environment. Speech and language therapy helps prepare them for lingual abilities. Lastly, occupational therapy can be provided to help with skills needed for independence in later life.
FAQs on Down Syndrome
1. What is the definition of down syndrome?
According to Down Syndrome definition biology, it is a chromosomal anomaly in which an error in cell division leads to an extra copy of chromosome 21 in the body. It is divided into 3 types – Trisomy 21, Mosaic Down syndrome, and Translocation.
2. What are the symptoms of down syndrome?
Down syndrome shows the following symptoms:
There may be physical symptoms such as short stature with a small neck, flat nasal bridge, low muscle tone, slant eyes, a large gap between the first and second toe, tooth enamel degradation, crowded teeth, etc.
The syndrome also manifests through cognitive disabilities such as mild or moderate intellectual disability, delay in the development of motor skills and language development, etc.
3. How is down syndrome diagnosed?
Down syndrome can be diagnosed prenatal or in early infants through genetic screening. Ultrasound screening can also be employed during gestation, as a foetus with down syndrome shows late/ absence of nasal bone development (in 14-20 weeks old foetus) along with various anatomical biomarkers for the disorder (such as abnormal right subclavian artery). Blood tests alongside other invasive techniques are known to improve the screening result and rightful detection by 98.6% during the first trimester of pregnancy.
4. How can down syndrome be managed in affected individuals?
Individuals diagnosed with down syndrome require lifelong special care and assistance from people around them. Several efforts such as early childhood intervention, screening for common problems and medical treatment wherever indicated, a good family environment, and work-related training can improve the development of children with Down syndrome. Education and proper care have been known to improve the overall quality of life.
5. How can learning and cognitive development be assisted in children diagnosed with down syndrome?
Individuals with Down Syndrome are known to learn better with visual aids and activities such as drawing, painting, picture comprehension, etc. along with training on speech and reading skills, can greatly help them in further formal education/ school learning. Some schools also offer custom-designed curriculum to address the special needs of such children and help them achieve an inclusive form of educational experience.
