Down's syndrome, or trisomy 21, is a chromosomal abnormality caused by an extra chromosome 21. This article explains the symptoms, diagnosis and treatment options for this condition.
Key points
- Down's syndrome is caused by an extra chromosome 21, resulting in various intellectual deficits and physical malformations.
- There are three main types of trisomy 21: free trisomy, mosaic trisomy and translocation trisomy, each with unique implications.
- The management of Down's syndrome is based on an early, multidisciplinary approach, combining medical care, educational support and awareness-raising initiatives to improve the quality of life of those affected.
Understanding Down's syndrome
Down syndrome is a chromosomal abnormality. It is caused by an extra chromosome 21. People with trisomy 21 have three chromosomes 21 instead of two, resulting in various intellectual deficits and physical malformations. The condition, first identified by British doctor John Langdon Down in 1866, affects around 300 genes that cause imbalances in the way the genome functions. Manifestations can appear throughout life, with significant impacts on the individual's physical and intellectual development.
The consequences of Down's syndrome include intellectual disabilities and physical malformations such as microcephaly and reduced growth. Affected children may experience delays in physical and psychomotor development, as well as intellectual disability, which varies considerably from one individual to another.
Healthcare and educational support play a crucial role in improving the quality of life and development of people with this syndrome.
Types of trisomy 21
There are several forms of trisomy 21, each resulting from a specific chromosomal abnormality. The three main types are free trisomy, mosaic trisomy and translocation trisomy.
Each of these forms has distinct characteristics and unique implications for those affected.
Free trisomy
Free trisomy is the most common form of trisomy 21, accounting for around 95% of cases. It is characterised by the presence of three separate 21 chromosomes. This condition generally occurs as a result of an error in the distribution of chromosomes during the first cell division, more specifically by non-disjunction during meiosis.
In free trisomy, the embryo receives a gamete with a double copy of chromosome 21, often inherited from the mother. The presence of an extra chromosome 21 results in the various symptoms and characteristics associated with Down syndrome, profoundly influencing the physical and intellectual development of individuals.
Mosaic trisomy
Mosaic trisomy is a rarer form of trisomy 21, accounting for around 2-3% of cases. It is characterised by the presence of two different cell populations: some cells have 46 chromosomes, while others have 47, including three 21 chromosomes. The proportion of cells with 46 or 47 chromosomes varies depending on when the anomaly occurred in the development of the organism.
This variability leads to clinical manifestations that may be less severe than those observed in free trisomy. The effects of mosaic trisomy can vary considerably from one individual to another, influencing their physical and cognitive development differently.
Translocation trisomy
Translocation trisomy is an inherited form of trisomy 21, occurring in around 3% of cases. In this condition, a chromosome 21 is attached to another chromosome, often chromosome 14. This means that individuals have two free chromosomes 21 and an extra chromosome 21 attached to another chromosome.
Translocation trisomy can be inherited from one of the parents, and karyotyping of the parents is necessary to identify carriers of this anomaly. This form of trisomy 21 requires special attention in terms of prenatal diagnosis and genetic counselling for the families concerned.
Physical and cognitive characteristics
The manifestations of Down's syndrome include a wide range of physiological, neurological and behavioural characteristics. Individuals with Down's syndrome often have distinct physical characteristics and variable intellectual impairment, influencing their development and quality of life.
Morphological signs
Children with Down's syndrome often have distinct facial features such as upward-slanting eyes, a flat face and a flattened nasal saddle. These clinical signs often allow the diagnosis to be suspected from birth.
Other physical features include a single palmar crease, smaller hands and feet, and poor muscle tone. These abnormalities are often observed by doctors and help to confirm the diagnosis of trisomy 21.
Individuals with Down's syndrome frequently have an open mouth with a furrowed and protruding tongue. These morphological signs are essential for early diagnosis and the implementation of appropriate care strategies, particularly for different languages.
Intellectual development
The main disability of people with Down's syndrome is intellectual disability, which varies considerably from one individual to another. The IQ of people with Down's syndrome can range from 30 to 70, with an average of around 50.
The physical and mental development of children with Down's syndrome is often delayed, requiring early interventions to maximise their potential. Here are some key interventions:
- Special education, which is tailored to each child's individual needs.
- Cognitive stimulation programmes, which aim to improve intellectual skills.
- Socialisation activities, which help to develop social skills.
These interventions are crucial to improving the intellectual and social skills of individuals with Down's syndrome.
Diagnosis of Down's syndrome
Diagnosis of Down's syndrome can be made before or after birth, using various techniques to identify the presence of an extra chromosome 21.
These methods enable chromosomal abnormalities to be detected and appropriate treatment to be planned.
Before birth
Non-invasive prenatal screening (NIPS) detects foetal DNA in the mother's blood to assess the risk of trisomy 21. This method, along with nuchal translucency measurement in the first trimester, is commonly used for early screening.
To confirm the diagnosis, chorionic villus sampling or amniocentesis may be carried out before birth. These techniques enable samples of foetal cells to be obtained for detailed chromosomal analysis.
After birth
After birth, the diagnosis of trisomy 21 is confirmed by a blood test to perform a karyotype, which reveals the presence of the extra chromosome 21. Puncture, like amniocentesis, is also a method used to confirm this diagnosis.
Additional tests are carried out to detect any associated anomalies, such as heart defects or digestive problems. Prompt treatment of these anomalies is crucial to prevent the condition of children with Down's syndrome from worsening.
Care and treatment
Caring for people with Down's syndrome requires a multidisciplinary approach and early intervention to maximise their abilities and improve their quality of life. This includes regular medical care and appropriate educational and social support.
Medical care
Regular monitoring by paediatricians is essential for the early detection and treatment of abnormalities such as thyroid disorders or hearing problems in children with Down's syndrome. Paediatricians play a crucial role from the very first days of life for children with Down's syndrome.
Children with Down's syndrome can develop complications such as heart and digestive malformations, as well as immune deficiencies. These congenital anomalies may require surgery to correct the problems and improve patients' quality of life.
Stimulation of psychomotor and speech development is also crucial, often requiring the intervention of specialists such as physiotherapists, psychomotor therapists and speech therapists. Early speech and language therapy and physiotherapy are generally considered to be useful for children with Down's syndrome.
Educational and social support
Instituts médico-éducatifs (IME) play an essential role in the care and support of children with Down's syndrome, providing qualified medical and paramedical professionals. However, access to these establishments can be limited due to long waiting lists.
Mainstream education is strongly recommended to improve socialisation and reduce marginalisation of people with Down's syndrome. Here are some of the advantages of this approach:
- Improved socialisation.
- Reduced marginalisation.
- Personalised support in activity programmes.
- Promotes well-being.
- Prevents isolation among adults with Down's syndrome.
This approach creates an inclusive and enriching environment for all.
Life expectancy and quality of life
Thanks to advances in medical care, the life expectancy of people with Down's syndrome has increased considerably.
These medical and educational advances are crucial to ensuring a better quality of life.
Progress in medicine
Medical discoveries have improved the life expectancy of people with Down's syndrome from a few years to over 60 years today. Early medical interventions, particularly in the cardiovascular field, have been decisive in increasing the survival of individuals with Down's syndrome.
Before:
Available treatments include regular medical care and specialised follow-up to manage the complications associated with Down's syndrome. Early interventions in rehabilitation and education have also played a key role in improving the functional skills of children with Down's syndrome.
After:
Treatments available include :
- regular medical care
- specialised follow-up to manage complications related to Down's syndrome
- early rehabilitation interventions
- educational interventions, which have played a key role in improving the functional skills of children with Down's syndrome.
Quality of life
To offer the best possible quality of life, it is crucial to detect the complications of trisomy 21 and to continue medical monitoring into adulthood. However, access to medical-educational institutes (IME) is often limited due to long waiting lists.
Initiatives are put in place on World Down's Syndrome Day to promote inclusion and improve the quality of life of people with Down's syndrome. These efforts contribute to better social integration and increased support for individuals with Down's syndrome.
Down's syndrome and society
People with Down's syndrome often face prejudice and stigma that affect their quality of life. Inclusion and awareness are essential to improve their social acceptance and well-being.
Stigma and inclusion
The stigma associated with Down's syndrome can further marginalise individuals, making their social inclusion even more difficult. Education and awareness programmes are essential to reduce this stigma and promote acceptance.
World Down's Syndrome Day aims to raise awareness of the challenges faced by people with Down's syndrome. Established in 2006, the day seeks to defend the rights and dignity of people living with Down's syndrome.
World Down's Syndrome Day
World Down's Syndrome Day, celebrated on 21 March, aims to promote inclusion and awareness of this genetic condition. The event is a reminder of the importance of equal rights and dignity for people with Down's Syndrome.
Activities and awareness campaigns are organised around the world to promote understanding and acceptance of people with Down's Syndrome. These initiatives play a crucial role in improving their quality of life and social integration.
In a nutshell
In summary, Down's syndrome is a complex condition that requires comprehensive and inclusive care. Medical and educational advances have considerably improved the life expectancy and quality of life of people with Down's syndrome. It is essential that we continue to raise society's awareness and promote inclusion to enable these individuals to live full and dignified lives. Together, we can create a world where every person, regardless of their chromosomes, is valued and respected.
Frequently asked questions
What is trisomy 21?
Trisomy 21, or Down's syndrome, is a chromosomal abnormality resulting from an extra chromosome 21. This condition has various impacts on the development and cognitive abilities of the individual.
What are the types of trisomy 21?
The three main types of trisomy 21 are free trisomy, mosaic trisomy and translocation trisomy. Each of these types has distinct characteristics and can have varying impacts on the health of the people concerned.
How is trisomy 21 diagnosed before birth?
Prenatal diagnosis of trisomy 21 is mainly carried out by measuring nuchal translucency and non-invasive prenatal screening (NIPS). These methods make it possible to assess the risk of this chromosomal anomaly before birth.
What medical care is needed for children with trisomy 21?
Children with trisomy 21 require regular medical monitoring by paediatricians, as well as surgery and early rehabilitation through speech therapy and physiotherapy. Providing this care is crucial to their optimum development.
What is the life expectancy of people with Down's syndrome today?
Life expectancy for people with Down's syndrome is currently estimated at between 50 and 60 years, with the prospect of reaching 70 in the near future. This reflects significant advances in care and support.
Original content from the Upbility writing team. Reproduction of this article, in whole or in part, without credit to the publisher is prohibited.
