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An insight into Down’s syndrome

By Dr. Lahiru Peiris of Base Hospital Thambuttegama

This world is a beautiful and precious place and it belongs to each and every one of us. From humans to animals, we all have equal rights to live on this planet. It doesn’t matter whether you are fair or dark, tall or short, rich or poor. We have all gone through various medical-related issues since we were born. Those medical issues can arise when we are exposed to the world or they may be generated through genetics.

Down’s syndrome is one of the most common genetic disorders in the world, with a worldwide prevalence rate of one in 700 births. Typically, you have 46 chromosomes from both the mother and father, which are 23 pairs, but in Down’s, you get an extra copy of a chromosome, which is chromosome 21. This occurs shortly after fertilization. This extra chromosome will give rise to various medical issues.

This syndrome was first described by an English physician called John Langdon Down in the late 19th Century. It was the French physician Jerome Lejeune who discovered that Down’s syndrome is a chromosomal disorder.

Types 

  1. Trisomy – during cell division, there will be an error which is called nondisjunction. That nondisjunction will cause chromosome 21 instead of the usual two. Then, that extra chromosome will develop in each and every cell in the body. 95% of Down’s syndrome cases are Trisomy 21
  2. Mosaicism – here, all the cells do not consist of 46 chromosomes. Some cells will consist of 47 chromosomes. People with Mosaic type will show fewer features compared to Trisomy 21. 1% of cases are found to be Mosaic
  3. Translocation – the total number of chromosomes is static but an extra pair of (complete or partial) chromosome 21 attaches to another chromosome. 4% of cases of Down’s syndrome are translocation

The causes or risk factors for Down’s syndrome are still a mystery but some researchers have found out that there is a link between older maternal age and Down’s syndrome.  There is not enough data to prove a link between Down’s and how the environmental factors, parental activities, or family history of Down’s affect the outcome in pregnancies (except for 1% of translocation).

Diagnosis of Down’s can be made before birth and after birth. Highly invasive diagnostic screening tests such as amniocentesis and chorionic villus sampling can be used, but those tests can give 2-5% of false-positive results. Those tests also may cause abortions. Chorionic villus sampling is done 10 weeks before the gestational age and amniocentesis can be performed 15 weeks before the gestational age.

In western countries, more than 90% of pregnancies are terminated after the screening tests. 

After birth, a test called karyotyping can be performed to confirm the diagnosis.

 

Signs and symptoms of Down’s syndrome

 

  • Flattened face – over the bridge of the nose 
  • Small head
  • Almond-shaped eyes – upward slanting
  • Small ears – below the lateral end of eyes
  • Short neck
  • Small mouth
  • Small hands and feet
  • Single palmar crease
  • Higher web space between the big toe and second toe
  • Shorter in height
  • Weak/floppy muscle tone 

Most of the above features can be detected even just a few hours after the birth of the child.

Some babies with Down’s syndrome can end up with major medical problems. 

These include, 

  1. Congenital heart disease – atrioventricular septal defect, ventricular septal defect
  2. Gastrointestinal problems – duodenal atresia
  3. Pneumonia
  4. Thyroid diseases 
  5. Hearing loss
  6. Vision problems
  7. Leukemia 
  8. Delay in development
  9. Fertility failure
  10. Mental abnormalities

Parents’ major concern is how to cure this syndrome but unfortunately, there is no cure for this condition. However, multidisciplinary care can be provided for the baby to prevent future medical problems as mentioned above. Early intervention can be performed to prevent major complications.

The multidisciplinary team involved in carrying out the relevant interventions consists of physicians, specialised consultants, special educators, speech therapists, occupational therapists, and also social workers. Some might need special schools to develop their educational skills.

The prognosis can be variable depending on the baby’s condition and future complications. Average life span will be around 50-55 years if there are no complications with major medical issues. Men will be sterile but women can be fertile. However, there is a high chance of giving birth to a Down’s baby. Some might go on to develop Alzheimer’s disease.

Advice that should be given to parents:

  • They will be like all other babies except for delays in starting activities
  • They could grow up to be musicians and even dancers
  • Learning disabilities can be detected, and they need special attention
  • Psychological counselling can be helpful

Doctor’s tips

  1. Down’s is a genetic disorder
  2. No cure has been found yet
  3. Early screening can be performed before the birth of the child
  4. It requires multidisciplinary management
  5. Activities and development may be delayed compared to other children