Down Syndrome

In this post, we are going to discuss about down syndrome, its causes, types, features (symptoms), complications and risk factors.

A case study

They have been trying to have another child. But after they had their daughter 10 years ago, 5 years into their marriage, the road to that possibility had just been shut to them.

At 40 and with menopause fast closing in on her with the lightning speed of Bolt, the chances were so slim it was almost non-existent.

But he still needed an heir, someone to carry the family name long after he was gone. And she would give her life to give him just that. A patient and an understanding husband, one who is always there to catch the fiery darts fired her way by nosy relatives concerning this same issue, that was the least he deserved.

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They were a struggling pair of peasants, who has managed to become “comfortable” and be able to provide for the apple of their eyes by being frugal with funds. When he got a major breakthrough in his business, it was such a relief. At about the same time she missed her period, but she wrote it off as onset of menopause. But she missed it again and yet again. And she was having this irresistible urge to throw up in the early hours of the morning.

It had been long she was last pregnant, so long she had forgotten what it felt like in the first trimester of pregnancy. So, she was surprised when she went to the hospital to “get treated for Malaria” and they told her she was pregnant.

Finally, the baby came. It was a male child, and he was so beautiful and adorable. But there was this funny look to his face, and the way he was always sticking out his tongue as if the mouth were not enough for it. Those were the things that made him more special and adorable anyway.

He was not just late in coming into their lives, he was also late in carrying his head, late at sitting on his own, late at standing, and late walking. He was just late in everything, and it was giving them major concern.

It was not long before it was apparent that their cute Onochie was mentally handicapped. He wasn’t like other kids, he was dull to understanding, always had this smirk on his face, his tongue sticking out almost all the time and him drooling saliva, and he was almost always having this or that chest infection, one after the other.

People started talking; he must have used his boy for blood money. Wasn’t it a little bit too coincidental that he had to have a financial breakthrough of the proportion he had just about the same time the wife got pregnant, and later delivered an “imbecile” …????

It wasn’t the enormous challenge of raising a child with special needs that hurt most, nor the shattering of their dream of having an Onochie, someone that would “replace” him when he is gone; but the insensitive and outrightly mean remarks people were making.

If only they were in their shoes and knew how painful the pinch was ….

The above scenario depicts a case of Down Syndrome, and what an enormous emotional cum psychological burden it could be for the family unit.

What is Down Syndrome?

Down Syndrome is a GENETIC disorder [of the CHROMOSOMAL variety] in which there is extra copies of Chromosome number 21 leading to mental retardation and a host of abnormalities in physical appearance termed DYSMORPHIC FEATURES.

It is the commonest cause of intellectual disability [and mental retardation] worldwide, affecting about 1 child in every 700 to 1000 live births.

Because of the characteristic facial appearance in people with Down syndrome, the so called dysmorphic facie, which arguably resembles the facial features of the Mongols of Asia, it is also called MONGOLISM.

But of recent this expression is no longer acceptable as the Mongols of Asia frowns at using their race to describe a disease associated with mental retardation.

Causes and Types of Down Syndrome

Unfortunately, the causes of Down syndrome can only be discussed meaningfully on the basis of genetics and at the cellular level. For a country like Nigeria where Selective Feticides [selective killing of an unborn child based on certain features undesirable to the parents] is frowned at, it makes conscious efforts at prevention almost impossible.

The causes of Down syndrome would best be understood if we first understand that each cell has 23 pairs of chromosomes, numbered from 1 to 23 with each pair of chromosomes having an identity assigned to it by virtue of its number. Chromosomal abnormalities arise when the “chromosomal citizens” of a cell instead of pairing up to form “couples” decides to stay “single and unmarried” or decides to be playing “threesome”.

In Down syndrome, the cellular citizen Chromosome number 21 decides to play threesome with resultant disharmony in the home. This “threesome” can arise by any of the following mechanisms:

Meiotic Nondisjunction

Usually during gametogenesis [formation of sex cells, sperm and ovum], each chromosomal pair “divorce” [i.e. separates] so that what is in each sperm or ovum are just “divorcees”.

The reason for this is that when an egg and a sperm finally meet and throws a party [ i.e unites and conception takes place], the different divorcees would find partners and pair up again to become couples.

Thus, when a baby is born, it would have exactly 23 couples of chromosomes in its cells.

In meiotic nondisjunction however, chromosomal couple number 21 fails to divorce in the mother’s egg so that when it meets the divorced single chromosome 21 from the father’s sperm, they will form a threesome marriage leading to constant “domestic disharmony”.

The type of Down syndrome arising from this phenomenon is called TRISOMY 21 and is the commonest type, accounting for 95% of cases.

trisomy 21
Down syndrome-trisomy 21 Credit: kanyanat wongsa/shutterstock

Mitotic Nondisjunction

In this, something similar to what is obtainable above occurs. But this time, it occurs in the already formed and developing Zygote [Baby] and not in the sex cells of the parents [mother to be precise].

Thus, not all cells are affected, and hence this type of Down Syndrome is less severe.

The phenomenon is called MOSAICISM, and it accounts for only 1% of cases.

Translocation

In this type, the extra copies of Chromosome 21 that leads to Down syndrome is transferred , that is “translocated” from another chromosome [mostly chromosome 14 and 22]

See it this way: that the threesome in this case is due to one of the Chromosome 21 pair cheating with a hot babe/dude from the chromosome 14 or 22 couple.

This is called the ROBERTSONIAN type, and accounts for 4% of cases.

Features or symptoms of Down Syndrome

The physical feature of Down syndrome is characteristic and are referred to as dysmorphic features.

This includes:

  • A flat facial profile
  • Eyes slanting upwards
  • Eyes that are widely apart [hypertelorism]
  • Folds on the inner aspects of the eyelids [epicanthal folds]
  • Abnormally shaped ears that are set low
  • Smallmouth giving an impression of a large tongue almost always hanging out
  • A single line on the palm, instead of the normal three [Simian crease]
  • Larger than normal space between the 1st and second toe.
  • A lot of skin folds on the neck.
  • Shortened hands
  • Low muscle tone, so low the child appears floppy. In fact, if you carry them it would be as if they will slip and fall.
symptoms of down syndrome
symptoms of down syndrome- Credit:Double Brain/shutterstock

Complications of Down Syndrome

This includes the following:

  • Mental retardation
  • Hearing impairment
  • Delayed milestones [eg sitting, standing and walking much later than other kids]
  • Susceptibility to infections
  • Susceptibility to Leukaemia
  • Susceptibility to developing Alzheimer’s disease early in life
  • Congenital Heart defects
  • Susceptibility to Celiac’s disease
  • Abnormal intestines that may be blocked
  • Susceptibility to developmental problems like Attention Deficit Hyperactive Disorder [ADHD]
  • Hypothyroidism.
  • Infertility especially in males.

Risk Factors of Down Syndrome

  • Maternal Age
  • Family History

The commonest risk factor, perhaps the only one worth mentioning is Maternal age. The risk of having a child with Down syndrome increases with maternal age, with the exponential cut off being age 35 [years].

Thus, the possibility of a Woman under 20 years having a child with Down syndrome is 1 in 1550 chances. It increases to 1 in 350 at 35 years, 1 in 100 at 40years and 1 in 25 at 45 years!

This is because, with increasing maternal age, there’s higher risk of Meiotic nondisjunction. Simply put Chromosomes of old eggs are old school and old fashioned, they do not like getting “divorce”; they would rather put up with a “second wife” and play threesome.

Another risk factor is a past family history. This is usually true for the Robertsonian type.

Prevention

With almost everything happening at the cellular level, prevention is almost not feasible.

Selective Feticide may be a way out, but then those kids also have a right to live. Hence it is not practiced in Nigeria.

The only possible preventive measure would be marrying early and completing your family size before age 35. But even that is not fool proof. And even if you marry late or you married early but couldn’t have kids, wouldn’t you be happy to take a chance, bearing in mind that there’s no hard and fast rule that says “you must have a child with Down once you’re above 35″….?See what I mean? Prevention is not really worth discussing here.

All hope is not Lost

While people with Down Syndrome may have low IQ, hence the difficulty in understanding language and learning, they have high “Adaptive Behaviour” and thus can excel in learning day to day activities [activities of daily living] and fairly complex skills.

All they need is love, support and PATIENCE, and they will get there. Also enrolling them in Special Schools for the mentally challenged [which sadly are almost non-existent in Nigeria] would be of immense help.

Dedication

To all children with special needs, and to their Parents who despite all odds still stand by them providing them with love and care to the best of their ability.

About the author

Doctor

Dr Chibuike Joseph Chukwudum is a doctor who Studied Medicine and Surgery at Nnamdi Azikiwe University Awka. He is the former Medical Officer at Oakland specialist hospital,obosi.He also previously worked at Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State.