Tag: Down Syndrome
-
Down Syndrome : Symptoms, Causes, and Features
Continue ReadingWhat 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,
Hearing loss,
Poor vision,
Cataracts (clouded eyes),
Hip problems,
Dislocations,
Leukemia,
Chronic constipation,
Sleep apnoea (interrupted breathing during sleep),
Dementia (thought and memory problems),
Hypothyroidism (low thyroid function),
Obesity,
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.Â
- 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.
Share
Similar Post:
-
Down Syndrome: Causes, Symptoms, Diagnosis, & Treatment
Continue ReadingDown Syndrome: Causes, Symptoms, Diagnosis, & Treatment
Share
Similar Post:
-
Down Syndrome: Definition, Causes, Symptoms, and Diagnosis
Continue ReadingWhat is Down Syndrome?
We know that abnormality in a structure or function of a chromosome leads to various chromosomal abnormalities or disorders. These disorders sometimes make a human an unfit to live a comfortable life with a good healthy lifestyle.
However, these disorders sometimes lead to mortality of an individual even at birth or it also results in lower lifespan of a person.
Down syndrome is also a one such genetic disorder which results in various physical and mental retardation.
This condition is as a result of addition of an extra chromosome in the chromosome number 21 which is also known as trisomy of the chromosome 21.
This is considered as one of the leading genetic disorder in the world.
This condition was first observed by the physician named Langdon Down.
The important physical condition that affects the individual due to this disorder is mental retardation.
The individuals affected to this disease are mostly suspectable to other diseases such as leukaemia and Alzheimer’s disease.
This condition has no treatment or medication and it’s a life long syndrome. But people with this syndrome are practised in speech and language therapies to improve their intellectual activities.
Down syndrome can be diagnosed at the time of pregnancy itself, many such population can be reduced by the decision of the parents.
Causes of Down Syndrome
Down syndrome is due to the addition of one extra chromosome to an 21st chromosome, which is resulted due to the aneuploidy of the chromosome.
This extra chromosome is present in all cells of the body in the chromosome number 21.
This condition occurs 1 in 800 lives. The important risk factor to be consider here is the age of the mother, because the mothers who are above the age of 35 can pass this condition to their children.
Downs syndrome is due to abnormal cell division in the mitotic and meiotic phases, where the chromosome pair are separated and each chromosome are allowed a get another copy of the chromosome. Which results in giving rise to unequal set of chromosomes. This process is generally known as non-disjunction of chromosomes.
Non-disjunction of chromosomes results when the chromosomes are segregated before all of the segregated chromosomes.
The daughter cells contain less chromosome with one extra chromosome, where the kinetochores are attached to the microtubules during metaphase at the opposite poles.
Down syndrome also occurs if translation occurs between two parts of the chromosome. In this case the number of chromosomes is normal but they have an additional part along with them.
But there will be no change or missing of any information but there will be extra segment which results in mental retardation. Of the all-inherited syndromes, Down syndrome does not occur mostly through inheritance. Where as the translocated downs syndrome can be passed from parents to offspring and it is inherited, but here the inherited parent will not show any symptoms for this condition, as the gene is found hidden in them and they are considered as carrier of this disease.
The individuals having this syndrome has a life span of about 60 years approximately.
Types of Down Syndrome
Down syndrome is generally classifying as three types as Trisomy of chromosome 21, Mosaicism, translocation.
I. Trisomy of Chromosome 21
Trisomy of chromosome 21 is the most happening and common type of downs syndrome. Here the extra number of chromosomes is present in the chromosome number 21 which leads to 47 number instead of 46 number of chromosomes.
The main reason for this condition is due to the non-disjunction of chromosomes during meiosis at the time of gamete formation.
Mosaicism
This condition occurs when non-disjunction of chromosomes occur in the mitotic division during the formation of zygote, at the time of fertilization.
This is the rarest type of syndrome occurring in humans. It is considered as mosaicism because some cells have normal 46 number of chromosomes where as the other cells contain extra chromosome which means 47 chromosomes.
Symptoms are not much severe in mosaicism. This condition is very rare among individuals.
Translocation
This condition occurs when the translocation occurs in the long arm of the chromosome. Where the q arm of the chromosome 21 gets translocated to the other chromosome. Where this portion of chromosome get located often to the chromosome 14.
This condition is not due to the mothers age or any other factors it is because of the inherited conditions.
Symptoms of Down Syndrome
People who are suffering with downs syndrome has many abnormalities in both physical and mental condition.
They have very poor immunity, so that they get easily affected with many diseases, such as sleep apnea, gastrointestinal defects, heart defects, thyroid infections.
They are also easily affected with Alzheimer’s and leukaemia.
The people with these conditions can be identified easily through their physical appearance and their activities. After every stage of life, they come across different symptoms.
The infants with this syndrome start growing slowly and they remain short as compared to others of same age.
The main symptoms of this syndrome are stunted growth with short stature, and fold of a flap of skin above the eyes with slanted eyes, protrusion of tongue and flattened nose, mental retardation, cardiac deformities, poor muscle tone but they have good flexibility, and as they have poor language development, they need language therapy and cognitive impairment.
Diagnosis of Down Syndrome
Children with this syndrome are often diagnosed after birth. But due to their different physical structures they are easily identifiable.
If these disorders are identified after birth they cannot be treated or cured. But the activities of the individual can be corrected through undergoing therapies.
It can also be diagnosed before giving birth by amniocentesis, where the amniotic fluid is taken from the mother’s womb with the help of the needle and they are tested by karyotyping as the genetic content of the amniotic fluid the foetus is same.
If the foetus is found to be abnormal, then it is aborted with the parents decision. However, this condition is becoming more common in every region in the world.
Down Syndrome Citations
- Integrated care for Down syndrome. Congenit Anom (Kyoto) . 2016 May;56(3):104-6.
- Down syndrome. Pediatr Clin North Am . 1993 Jun;40(3):523-35.
- Down syndrome, increased risk of dementia and lipid disturbances. Dev Period Med . 2017;21(1):69-73.
- Role of the family physician in the care of children with Down syndrome. Am Fam Physician . 2014 Dec 15;90(12):851-8.
- 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.
Share
Similar Post:
