Introduction to Edward Syndrome UPSC

Welcome to PreCrack! Recently, scientists has been found the Prehistoric skeletal remains. These remains are up to 5,500 years old. This has been revealed the first identified case of Edwards syndrome, a chromosomal disorder, alongside six cases of Down syndrome. This has been provided the insights into ancient genetic disorders.

Why Edward Syndrome is in the news?

Edward syndrome, or Trisomy 18, made headlines as researchers uncovered a groundbreaking discovery in prehistoric skeletal remains, dating back around 5,500 years. This marks the first identification of Edwards syndrome in historical or prehistoric contexts.

What is Edward Syndrome? – Edward Syndrome UPSC

Trisomy 18, also known as Edwards syndrome, is a genetic disorder where individuals have an extra copy of chromosome 18. This condition leads to various health issues, such as slow growth before birth, low birth weight, and heart defects. Babies with Trisomy 18 often display physical features like a small head, a tiny jaw, and clenched fists.

Complete Details about Edward Syndrome / Trisomy 18 UPSC

We have added a complete set of details about Edward Syndrome below-

Definition

A genetic disorder, identified by the presence of an extra chromosome 18 and associated with conditions such as slow growth, heart defects, and a high mortality rate, is termed Edward Syndrome, or Trisomy 18.

Description

Edward Syndrome, or Trisomy 18, is a rare genetic disorder marked by an extra chromosome 18. It leads to severe health complications, including slow growth, heart defects, and a high mortality rate, with most affected individuals not surviving beyond their first year.

About Edward Syndrome

We can get to know about Edward Syndrome easily by following points-

1. Chromosomal Disorder: Edward Syndrome, also known as Trisomy 18, is a genetic disorder characterized by the presence of an extra copy of chromosome 18.
2. Health Impacts: Individuals with Trisomy 18 often experience slow growth before birth, low birth weight, and various physical abnormalities, including heart defects.
3. Limited Survival: Unfortunately, many affected individuals face life-threatening complications and have a high mortality rate, with most not surviving beyond their first year of life.
4. Genetic Origin: The condition is typically caused by problems during the formation of reproductive cells or early development, and it is associated with increased maternal age.
5. Rare Incidence: Trisomy 18 occurs in approximately 1 in 5,000 live births, making it a relatively rare chromosomal disorder.
6. Diagnostic Methods: Prenatal screening through ultrasound and amniocentesis is commonly used to detect Trisomy 18 and confirm the diagnosis.
7. Supportive Care: There is no cure for Trisomy 18, and treatment focuses on providing supportive care to manage the associated health issues.
8. Named after Geneticist: The syndrome is named after English geneticist John Hilton Edwards, who first described it in 1960.

Its features or Characteristics

These are the key features or considered as key characteristics of Edward Syndrome-

1. Clenched Hand and Overlapping Fingers

People with Edwards syndrome often have clenched hands, where the index finger overlaps the third, and the fifth overlaps the fourth due to joint contracture.

2. Heart Defects

Commonly present at birth, structural heart issues like ventricular septal defect and atrial septal defect are associated with Edwards syndrome.

3. Kidney Malformations

Abnormalities in kidney structure are a part of the varied features of Edwards syndrome.

4. Omphalocele

A characteristic trait involves the intestines protruding outside the body, seen in individuals with Trisomy 18.

5. Esophageal Atresia

Edwards syndrome may include abnormalities in the structure of the esophagus.

6. Intellectual Disability

Cognitive challenges are common in individuals affected by Trisomy 18.

7. Developmental Delays

Slower progress in achieving developmental milestones is a distinctive feature of Edwards syndrome.

8. Growth Deficiency

Individuals often experience slow growth and low birth weight associated with this genetic disorder.

9. Feeding Difficulties

Challenges related to feeding are frequently observed in those with Trisomy 18.

10. Breathing Difficulties

Respiratory issues may be present, contributing to the health challenges associated with Edwards syndrome.

11. Arthrogryposis

A muscle disorder causing joint contractures is seen in individuals with Trisomy 18.

12. Microcephaly

Abnormally small head size is a common physical trait associated with Edwards syndrome.

13. Occiput Prominence

A distinct back portion of the head is often noted in individuals with Trisomy 18.

14. Facial Abnormalities

These include low-set, malformed ears, a small jaw, cleft lip/cleft palate, upturned nose, narrow eyelid openings, and widely spaced eyes.

15. Skeletal Anomalies

Various skeletal abnormalities, such as a short breast bone, absent radius, webbing of the second and third toes, clubfoot, or rocker bottom feet, are common in Trisomy 18.

16. Male-Specific Features

Undescended testicles may be observed in males affected by Edwards syndrome.

17. Prenatal Characteristics

In utero, common characteristics include cardiac anomalies and central nervous system anomalies. Choroid plexus cysts, an intracranial anomaly, may be present. Excess amniotic fluid or polyhydramnios and, albeit uncommon, Dandy–Walker malformation are associated with Trisomy 18 in prenatally diagnosed cases.

Causes

Edwards syndrome, also known as Trisomy 18, is caused by the presence of an extra copy of chromosome 18 in an individual’s cells. This occurs due to a random event during cell division, either in the egg or sperm, before conception. The specific cause of the extra chromosome is not fully understood, but it is known to be a sporadic and random occurrence.

Genetics of Edward Syndrome

We can understand the genetics of this Edward Syndrome by following points-

1. Chromosomal Abnormality: Trisomy 18 results from an extra copy of genetic material on the 18th chromosome, either in whole (trisomy 18) or in part (partial trisomy 18 due to translocations).
2. Nondisjunction Event: Trisomy 18 is primarily caused by meiotic nondisjunction, where a pair of chromosomes fails to separate during cell division, leading to an extra chromosome in a gamete.
3. Preconception Occurrence: The additional chromosome usually occurs randomly in the egg or sperm before conception.
4. Haploid Number Increase: Numerical errors during meiotic divisions can cause the failure of a chromosome to segregate, resulting in an extra chromosome and increasing the haploid number from 23 to 24.
5. Fertilization and Trisomy: Fertilization of an egg or insemination by sperm with an extra chromosome leads to trisomy, where the embryo has three copies of the problematic chromosome, in this case, chromosome 18.

Epidemiology

We can understand the Epidemiology (Study of health patterns) of Edwards Syndrome by following points:-

1. Overall Prevalence

Approximately 1 in 5,000 births is affected by Edwards syndrome, with reported estimates ranging from 1 in 3,600 to 1 in 10,000.

2. Live Births

The prevalence is lower in live births, estimated at around 1 in 8,600 in the United States. The disorder is associated with a higher likelihood of miscarriage, particularly in male fetuses.

3. Sex Ratio

Edwards syndrome exhibits a notable sex ratio, with a 3:2 ratio favoring females. However, the higher live birth rate for females is attributed to a higher likelihood of miscarriage in male fetuses.

4. Geographical Variations

Prevalence can vary across countries and regions, influenced by factors such as differences in prenatal testing practices and termination rates.

5. Age-Related Risk

The risk of having a child with Edwards syndrome significantly increases with maternal age. Advanced maternal age is associated with a higher probability of errors during cell division, contributing to the elevated risk.

6. Seasonal Variation

Some studies suggest a potential seasonal variation in the incidence of Edwards syndrome, with a higher reported prevalence in specific months like February-April. However, further research is needed to confirm and understand this observation.

Etiology

The etiology of Edwards syndrome, also known as Trisomy 18, lies in a chromosomal abnormality where there is an extra copy of genetic material on the 18th chromosome. This additional chromosome typically occurs as a result of a random event during cell division, either in the egg or sperm, before conception. The specific cause of the extra chromosome is not fully understood, but it is considered a sporadic and random occurrence.

Genotype

The genotype in Edwards syndrome refers to the unique chromosomal composition of individuals affected by the condition. In all types of Edwards syndrome, the defining feature is the presence of three copies of chromosome 18 (3q18), in contrast to the usual two copies in healthy individuals (2q18).

Breaking down the genotypes in different types of Edwards syndrome:

1. Full Trisomy 18

The most common type where every cell in the body carries three copies of chromosome 18. For females, it is denoted as 47,XX,+18, and for males, it is 47,XY,+18.

2. Mosaic Trisomy 18

Only some cells in the body possess three copies of chromosome 18, while others have the typical two copies. The proportions of cells with different genotypes vary, contributing to the diverse clinical presentations observed in mosaic trisomy 18.

3. Partial Trisomy 18

The rarest type, where only a portion of the extra chromosome 18 is present in some cells. The specific segment of the chromosome involved determines the features and severity of the condition. The genotype in such cases can be represented as a complex formula reflecting the missing or duplicated chromosomal segments.

Chromosome Formula of Edward Syndrome

The chromosomal formula for Edwards syndrome depends on the specific type:

1. Full Trisomy 18:

• Females: 47,XX,+18
• Males: 47,XY,+18
• Explanation: “47” indicates an extra chromosome (compared to the usual 46), “XX” or “XY” represents sex chromosomes, and “+18” signifies the extra chromosome 18.

2. Mosaic Trisomy 18:

• Example for Females: 46,XX / 47,XX,+18
• Example for Males: 46,XY / 47,XY,+18
• Explanation: Represents two cell lines, one with normal chromosomes (46,XX or 46,XY) and another with an extra chromosome 18 (47,XX,+18 or 47,XY,+18). Proportions vary, impacting severity.

3. Partial Trisomy 18:

• Example: 46,XX,dup(18)(q12.2q21.1)
• Explanation: Denotes a duplication on the long arm of chromosome 18, between regions q12.2 and q21.1. Formula reflects the specific chromosomal segment affected in this trisomy 18 type.

Complications

There are several complications of this Edward Syndrome:-

1. Failure to Thrive: Difficulty in gaining weight and growing properly, leading to underdevelopment.
2. Severe Intellectual Disability: Significant delays in cognitive development, impacting learning and daily activities.
3. Musculoskeletal Problems: Low muscle tone and joint stiffness, causing developmental delays and mobility issues.
4. Speech and Language Delays: Challenges in communication and language understanding due to cognitive delays.
5. Heart Defects: Complex structural issues in the heart, increasing the risk of infections and circulatory problems.
6. Kidney Malformations: Abnormalities in the kidneys that may lead to chronic kidney disease and the need for interventions.
7. Gastrointestinal Issues: Defects in the intestines, hernias, and feeding difficulties contributing to malnutrition.
8. Central Nervous System (CNS) Malformations: Impact on motor skills, cognitive development, and sensory functions.
9. Susceptibility to Infections: Weakened immune systems resulting in frequent and severe infections.
10. Seizures: Occurrence due to abnormalities in brain development and electrical activity.
11. Vision and Hearing Problems: Issues arising from malformations or complications, affecting sensory perception.
12. Psychological Issues: Emotional challenges, anxiety, and frustration due to limitations and communication difficulties.
13. Scoliosis: Curvature of the spine, leading to posture and movement problems.
14. Hydrocephalus: Accumulation of fluid in the brain causing increased head size and pressure.
15. Respiratory Problems: Structural abnormalities impacting breathing and increasing the risk of infections.
16. Cardiac Anomalies: Complex heart defects affecting circulation and elevating the risk of infections.
17. Undescended Testicles: Presence in males, contributing to reproductive challenges.
18. Recurrent Urinary Tract Infections: Due to kidney and urinary system abnormalities.
19. Omphalocele: Protrusion of abdominal organs through the abdominal wall.
20. Esophageal Atresia: Malformation of the esophagus, affecting feeding and digestion.

Effects

The effects of Edwards syndrome are extensive and impact various aspects of an individual’s health and development. These effects can vary in severity and may involve multiple organ systems. Here is an overview of the effects associated with Edwards syndrome:

1. Physical Growth Impairment: Failure to thrive, leading to difficulties in gaining weight and growing appropriately.
2. Intellectual and Developmental Challenges: Severe intellectual disability resulting in significant delays in cognitive development.
3. Musculoskeletal Issues: Low muscle tone, joint stiffness, and developmental delays affecting motor skills.
4. Communication and Language Difficulties: Challenges in speech and language development due to cognitive delays.
5. Cardiac Anomalies: Complex heart defects, including ventricular septal defect and atrial septal defect, impacting circulatory function.
6. Renal (Kidney) Abnormalities: Malformations in the kidneys, potentially leading to chronic kidney disease.
7. Gastrointestinal Aberrations: Intestinal defects, hernias, and feeding difficulties contributing to malnutrition.
8. Central Nervous System Malformations: Impact on the brain’s structure, influencing motor skills and sensory functions.
9. Susceptibility to Infections: Weakened immune system, making individuals more prone to frequent and severe infections.
10. Seizures: Occurrence due to abnormalities in brain development and electrical activity.
11. Vision and Hearing Problems: Issues arising from malformations or complications, affecting sensory perception.
12. Psychological Challenges: Emotional difficulties, anxiety, and frustration due to limitations and communication obstacles.
13. Scoliosis: Curvature of the spine, leading to posture and movement problems.
14. Hydrocephalus: Accumulation of fluid in the brain causing increased head size and pressure.
15. Respiratory Complications: Structural abnormalities impacting breathing and increasing the risk of respiratory infections.
16. Reproductive Challenges: Undescended testicles in males, affecting reproductive function.
17. Urinary Tract Issues: Recurrent urinary tract infections due to kidney and urinary system abnormalities.
18. Abdominal Wall Defects: Omphalocele, where abdominal organs protrude through the abdominal wall.
19. Esophageal Atresia: Malformation of the esophagus, impacting feeding and digestion.
20. Shortened Lifespan: Many individuals with Edwards syndrome face life-threatening medical problems, leading to a reduced lifespan. Survival beyond the first year is rare, and those who survive often have severe intellectual disability.

Diagnosis

There are two types of diagnosis can be considered. First is diagnosis before birth, second is after birth-

Prenatal (Before-Birth) Diagnosis

Screening Tests:

• Combined Test: Considers maternal age, blood tests, and ultrasound for estimating chromosomal abnormality risk.
• Non-invasive Prenatal Testing (NIPT): Analyzes fetal DNA in the mother’s blood, offering a higher detection rate.

Diagnostic Tests (If Screening Raises Concerns):

• Amniocentesis: Extracts amniotic fluid for chromosomal analysis.
• Chorionic Villus Sampling (CVS): Extracts placental tissue for chromosomal analysis.

Postnatal (After-Birth) Diagnosis

Physical Examination:

• Doctors assess for characteristic features like low birth weight, microcephaly, and specific facial characteristics.

Chromosome Analysis:

• Blood tests (karyotyping or FISH) confirm the presence of an extra chromosome 18.

Imaging Studies:

• X-rays, ultrasounds, or echocardiograms may be used to identify congenital malformations associated with Edwards syndrome.

Treatment / Cure

Unfortunately, there’s no cure for Edwards syndrome, but various treatments aim to enhance life quality and manage symptoms.

1. Supportive Care:

• Medical Help: Medicines and surgeries manage complications like heart issues and infections.
• Feeding Support: Specialized feeding methods ensure proper nutrition.
• Therapies: Physical and occupational therapies improve muscle strength and daily skills.
• Early Support Programs: Specialized services maximize developmental potential.
• Emotional Support: Counseling and groups help both individuals and families.

2. Specific Strategies:

• Breathing Help: Oxygen or machines may be needed for breathing difficulties.
• Seizure Control: Medications help manage seizures.
• Pain Relief: Medication and techniques address discomfort.

3. Research and Future Hope:

• Gene Therapy: Research explores genetic modifications for potential treatment.
• Improved Strategies: Ongoing research aims to enhance existing treatments.

Other Similar Types of Disorders

Edwards syndrome (trisomy 18) is a chromosomal disorder, but there are other genetic conditions with similar features and challenges. While not exactly similar, some share overlapping symptoms and involve chromosomal abnormalities. Here are some examples:

1. Down syndrome (Trisomy 21)

1. Most common trisomy, occurring in about 1 in 800 births.
2. Caused by an extra copy of chromosome 21.
3. Common features: intellectual disability, characteristic facial features, short stature, hypotonia (low muscle tone), heart defects.
4. While there is no cure, individuals with Down syndrome can live fulfilling lives with appropriate support.

2. Patau syndrome (Trisomy 13)

1. Rare trisomy, occurring in about 1 in 10,000 births.
2. Caused by an extra copy of chromosome 13.
3. Most babies with Patau syndrome do not survive beyond infancy due to severe malformations.
4. Common features: severe intellectual disability, characteristic facial features, multiple organ malformations (heart, brain, kidneys), cleft lip/palate.

3. Turner syndrome (Monosomy X)

1. Affects females, meaning they have only one X chromosome instead of the usual two (45,X).
2. Occurs in about 1 in 2,500 female births.
3. Features can vary, but may include short stature, delayed puberty, fertility issues, learning difficulties.
4. Hormone replacement therapy can help manage certain aspects of the condition.

4. Klinefelter syndrome (XXY)

1. Affects males, meaning they have an extra X chromosome (47,XXY).
2. Occurs in about 1 in 500 male births.
3. Features can vary, but may include tall stature, small testicles, reduced fertility, learning difficulties.
4. Hormone replacement therapy and other interventions can be helpful for some individuals.

5. Cri-du-chat syndrome (5p deletion syndrome)

1. Caused by a deletion of a small part of the short arm of chromosome 5.
2. Occurs in about 1 in 50,000 births.
3. Features: characteristic cry (sounding like a cat’s cry), intellectual disability, developmental delays, specific facial features.
4. No cure exists, but supportive care can address specific needs and improve quality of life.

Difference between Edward Syndrome and Down Syndrom

The Edward Syndrome and Down Syndrom has a few similarities but they are different. We have added the difference between Edward Syndrome and Down Syndrom below in the table-

Difference between Edward Syndrome and Patau Syndrome

Like Down Syndrome, Edward Syndrome and Patau Syndrome also have a few similarities but they are also different. We have added the difference between Edward Syndrome and Patau Syndrome below in the table-

Interesting Facts about Edward Syndrome

We have added a few interesting facts about Edward Syndrome below. You’ll be amazed to know that Edward Syndrome is…

1. Named After Geneticist: Edwards syndrome is named after English geneticist John Hilton Edwards, who first described the condition in 1960.
2. Chromosomal Abnormality: It is caused by the presence of an extra copy of chromosome 18 in a person’s cells, known as trisomy 18.
3. Rare Occurrence: Trisomy 18 occurs in about 1 in 5,000 live births, making it relatively rare.
4. Affects Many Organs: Individuals with Edwards syndrome often have abnormalities in various parts of the body, impacting organs such as the heart, kidneys, and brain.
5. Characteristic Hand Posture: One distinctive feature is the clenched hand with overlapping fingers, a result of congenital joint contracture.
6. Prenatal Diagnosis Challenges: Diagnosis during pregnancy is challenging, and advancements in genetic testing have aided in identifying cases, even from ancient skeletal remains.
7. Early Age of Death: Due to severe medical problems, many affected individuals do not survive beyond infancy. The survival rate is around 5-10%.
8. Geographical Variations: Studies suggest geographical variations in prevalence, influenced by factors like prenatal testing practices and termination rates.
9. Heart Anomalies Prevalent: Cardiac anomalies are common, and heart defects contribute significantly to the medical challenges associated with Edwards syndrome.
10. Ongoing Research for Hope: Despite the lack of a cure, ongoing research explores gene therapy and improved management strategies, offering hope for potential advancements in the future.

Key Facts about Edward Syndrome

FAQs on Edward Syndrome – UPSC Questions on Edward Syndrome

Question-1: What is Edwards syndrome?

Answer. Edwards syndrome, also known as Trisomy 18, is a genetic disorder caused by the presence of an extra copy of chromosome 18.

Question-2: How common is Edwards syndrome?

Answer. It occurs in about 1 in 5,000 live births, making it relatively rare.

Question-3: What are the common characteristics of Edwards syndrome?

Answer. Common characteristics include a small head, small jaw, clenched fists with overlapping fingers, and severe intellectual disability.

Question-4: Are there different types of Edwards syndrome?

Answer. Yes, there are different types, including full trisomy 18, mosaic trisomy 18, and partial trisomy 18.

Question-5: What causes Edwards syndrome?

Answer. Most cases result from problems during the formation of reproductive cells or early development. The risk increases with maternal age.

Question-6: Can Edwards syndrome be inherited?

Answer. Rarely, cases may be inherited, but most occur sporadically due to new mutations.

Question-7: How is Edwards syndrome diagnosed during pregnancy?

Answer. Prenatal diagnosis involves screening tests like ultrasounds and diagnostic tests like amniocentesis or chorionic villus sampling (CVS).

Question-8: Is there a cure for Edwards syndrome?

Answer. No, there is currently no cure for Edwards syndrome. Treatment focuses on supportive care to manage symptoms.

Question-9: What is the prognosis for individuals with Edwards syndrome?

Answer. The prognosis is generally poor, with a high percentage of affected pregnancies resulting in stillbirth. Survival beyond infancy is limited.

Question-10: Are there specific risk factors for having a child with Edwards syndrome?

Answer. The primary risk factor is maternal age, with an increased chance of occurrence in older mothers.

Question-11: What are the chances of having another child with Edwards syndrome after one affected pregnancy?

Answer. The risk of having a second child with Edwards syndrome is typically around one percent.

Question-12: What role does genetics play in Edwards syndrome?

Answer. Edwards syndrome is caused by an extra copy of genetic material on chromosome 18. It is not typically inherited from parents.

Question-13: Can Edwards syndrome be detected through genetic testing?

Answer. Yes, genetic testing such as karyotyping can detect the presence of an extra chromosome 18, confirming the diagnosis.

Question-14: How does Edwards syndrome affect prenatal development?

Answer. In utero, common characteristics include cardiac anomalies and central nervous system anomalies, such as head shape abnormalities.

Question-15: What is mosaic trisomy 18?

Answer. Mosaic trisomy 18 occurs when only some of the body’s cells have an extra copy of chromosome 18, resulting in a mixed population of cells with varying numbers of chromosomes.

Question-16: Are there physical malformations associated with Edwards syndrome?

Answer. Yes, physical malformations include a small head, low-set ears, cleft lip/cleft palate, and other facial features, as well as skeletal abnormalities.

Question-17: Can individuals with Edwards syndrome survive into adulthood?

Answer. While rare, some individuals with Edwards syndrome may survive into their twenties or thirties, but the majority do not live beyond infancy.

Question-18: How does Edwards syndrome impact intellectual development?

Answer. Individuals with Edwards syndrome typically experience profound intellectual disability and developmental delays, affecting learning and daily activities.

Question-19: Are there any treatments available for Edwards syndrome?

Answer. While there is no cure, supportive care is provided to manage symptoms, involving medical interventions, nutritional support, and therapy.

Question-20: What is the historical significance of Edwards syndrome?

Answer. Edwards syndrome was first identified by John Hilton Edwards in 1960, and it is named after him. Initially, he believed it to be caused by a trisomy of chromosome 17.