What is Down Syndrome?
Human being’s genes are preserved in the nucleus of the cells which comprises of genetic material and are capable of passing down the features from generations to generations and are usually present in a group/cluster of shape similar to a rod named as chromosomes.
Chromosomes are defined as a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
Cell in human beings contains twenty-three pairs of chromosomes which are partly inherited from either parent.
Synonyms for this condition include – 47,XX,+21, 47,XY,+21, Down’s syndrome, Trisomy 21, and Trisomy G. Whenever there are abnormalities, syndromes occur.
Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21 and this chromosome changes the pathway of development and leads to the features that are usually seen in down syndrome.
Most common features usually seen in the Down syndrome patients include are poor tone of the muscle, short stature, an upward slant to the eyes, and a single deep crease known as simian line in the center of the palm.
The severity of the symptoms depends on case basis, some may show severe features while the rest do not show and is variable.
Down Syndrome Epidemiology
In USA it is seen that almost one in every seven hundred babies are born with this abnormality – Centers for Disease Control and Prevention.
This is one of the most commonly found chromosomal abnormality and approximately six thousand infants are born with down syndrome every year.
Features of Down Syndrome
• Intellectual disability.
• Typical features of face like flat face, upward pointing of outer corners of the eyes (up slanting palpebral fissures), short ears, a short neck, and a tongue protruding out of the mouth.
• Hypotonia that is poor muscle tone in babies.
• Cognitive delays, but the intellectual disability is usually mild to moderate.
Cause of Down Syndrome
Chances of baby suffering from down syndrome increases with the woman who gives birth to the child in their old age.
Etiology of down syndrome includes trisomy 21, it has 3 copies of chromosome 21 rather than 2 which is normal.
Less frequently it is also seen when chromosome number 21 gets translocated to different chromosome early in fetal development when there is formation of the reproductive cells.
They have 2 copies of chromosome number 21 however they have additional contents from chromosome 21 stick to another chromosome which causes 3 copies of genetic components on chromosome number 21 which leads to the translocation Down syndrome.
An exceedingly small % with Down syndrome have an additional copy of chromosome 21 in other cells and this condition is termed as mosaic Down syndrome.
Scientists have suggested that this additional copy interferes with the usual developments thus leading to characteristic traits of down syndrome.
In the translocation Down syndrome, can occur with an unaffected parent since they have rearrangement of genetic material between chromosome 21 and another chromosome.
Such rearrangement is called a balanced translocation.
Since it is balancing no material related to genes is decreased or increased, hence such changes because of chromosomes often end up with health abnormalities.
When such translocation is passed to the next generation, it can become unbalanced and such people who inherit an unbalanced translocation pertaining to the chromosome 21 may have additional genetic material from chromosome 21, which leads to the Down syndrome.
Like trisomy 21, mosaic Down syndrome is not inherited.
It occurs as a random event during cell division early in fetal development.
Resulting, some of the body’s cells have the usual two copies of chromosome 21, and other cells have three copies of this chromosome.
Down Syndrome Symptoms
Individuals with Down Syndrome may have various birth defects, and they usually have small hands and feet and a simian line on the palms.
Almost 50% of the children born with down syndrome have heart defect, while defects in digestion, like blocking of the intestine, are less frequently seen.
Medical conditions in this patient heighten and are sometimes intolerant to gluten, suffer from GERD that is gastroesophageal reflux, flowing of stomach acids backward into oesophagus, and celiac disease.
Fifteen percent people usually have an underactive thyroid gland that is hypothyroidism.
They also usually have greater tendency of hearing and vision problems.
Also, few percent of the population suffering with Down syndrome gives rise to cancer like leukemia.
There is also speech delay seen in down’s patient with late development and behavioral problems like attention problems, obsessive/compulsive behaviour, and stubbornness or tantrums and usually suffer from problems pertaining to growth.
Moreover, speech may be hard to interpret in individuals with Down syndrome.
Sometimes they are diagnosed with autism spectrum disorders, that affects further their communication and social interaction and experiences a low decrease in their capacity to process (cognition) with increasing age beyond the age of 50 years.
Risk Factors in Down Syndrome
Medical conditions usually seen in such condition are:
Congenital heart defects,
Cataracts (clouded eyes),
Sleep apnoea (interrupted breathing during sleep),
Dementia (thought and memory problems),
Hypothyroidism (low thyroid function),
Late tooth growth,
Causing problems with chewing,
Another most important risk factor involved with Down syndrome is heightened risk of Alzheimer disease, which leads to slow loss of memory, loss of capacity to think, judgmental skills and capacity to function.
Down Syndrome Treatments
There is no full proof treatment available for down syndrome cases however, supportive therapy helps the patients to cope with it and includes special education teachers that will impart sensory skills, social skills, self-help skills, motor skills and language and cognitive abilities.
They usually attain developmental milestones but usually is late.
Schooling helps kids with Down syndrome with important socialization and to gain fundamentals of life.
The life span also has increased since last decade and now average life span in 50-60 years of age which usually used to be less than 10 years.
Though they face hardship, they never fail to work hard and give their 100% and thereby overcoming those obstacles and sustain.
It is essential that parents and community support such individuals with Down syndrome and their families.
Down Syndrome Citations:
- Down syndrome-A narrative review with a focus on anatomical features. Clin Anat . 2016 Jul;29(5):568-77.
- Down syndrome: Cognitive and behavioral functioning across the lifespan. Am J Med Genet C Semin Med Genet . 2015 Jun;169(2):135-49.
- Diagnosis and management of Down syndrome. Indian J Pediatr . 2014 Jun;81(6):560-7.
- Down syndrome–genetic and nutritional aspects of accompanying disorders. Rocz Panstw Zakl Hig . 2015;66(3):189-94.
- Down Syndrome. N Engl J Med . 2020 Jun 11;382(24):2344-2352.
- Down syndrome: a review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod . 1997 Sep;84(3):279-85.
- Endocrine manifestations of Down syndrome. Curr Opin Endocrinol Diabetes Obes . 2018 Feb;25(1):61-66.