Downs Syndrome
Background
Our humans characteristics such as physical appearance, hair colour, skin colour, and sex are controlled by genetic material which is located on each chromosome. In human body contains millions of cells and in each cell, there are 46 chromosomes, or 23 pairs. These chromosomes are from mother and father equally 23 chromosomes. This is the genetic inheritance.
From the drawing evidences it could be possible that Downs syndrome has been known since the 16th century. The first lecture on Downs syndrome was debuted in 1846 by Edouard Onesimus Sequin and in 1866 John Langdon Down gave the first description of a group of children with mental retardation. They look like Mongol and Down called this abnormality, Mongolism. The name was later disagreed to be used and to honor the discoverer the new name was given as Downs syndrome. Or the American style writes Down syndrome.
Down syndrome can be found in every race, culture, economical-status, and topography. In general, it can be found 1 out of 600-800 of new born babies. This incidence is, however, lower than what it should be because the down syndrome babies will be automatically abortive by 75%. Nevertheless, this kind is the most common chromosomal aberration cause of mental retardation and, even more, it is the most common genetic cause of mental retardation; this is 1 out of 3 of the moderate to severe mental retardation. The ratio of male to female is 1.3 to 1. Each year in the USA found around 10,000 new born down syndromes. In Thailand, if 1 million babies born per year, 1,000 babies would be found having down syndrome.
Down syndromes causes
It is form the aberration of the 21st pair of chromosome, however the mechanism of this order is still unclear. It is believed that the excess genetic material in pair 21 changes the normality of embryo development which causes the physical appearances in common such as small and flat head, flat face, flat nose, slant eyes, small mouth, small ears, short neck, broad hands, short fingers, simian crease lines, cleinodectyly, wide gap between toe fingers 1 and 2, including the abnormality of various systems such as heart and blood vessels, muscular, gastrointestinal, endocrinologic systems, etc. More importantly, these children will also have mental retardation which mostly are mild to moderate mental retardation.
Chromosome aberration found in Down syndrome
There are 4 kinds of chromosome aberration found in Down syndrome:
1. Trisomy 21 : there is 1 excessive chromosome on the pair 21. Most of the cases are caused from non-disjunction of the chromosome during the mother sex cell division. Only 10% are caused form the father sex cell division. That is, this type of abnormality occurs before the fertilization even though a few cases may happen at the first time of division after the fertilization. This abnormality is found by 95% of the Down syndrome without the clear understanding of its cause, however, the older the mother the more cases were found. The recurrent risk is 1% and this kind of chromosome aberration needs no parental chromosome study.
2. Robertsonian translocation: this kind can be found by 4% of the Down syndrome. There are 46 chromosomes, however, one of them is abnormal due to the translocation of the chromosome between pair 21 and pairs 13, 14, 15, 21, or 22. The most common is translocation between pair 21 and pair 14. The rate of translocation has no correlation with the maternal age. 50% of translocation happens spontaneously while the other 50% have their mother or father as carrier. Therefore, if found this case of chromosomal aberration parental chromosomal study shall be performed for couselling.
3. Mosaicism: there are 2 kinds of chromosomal aberration in the same person, i.e. some cells contain 46 chromosomes while some contain 47 chromosomes (trisomy 21). This kind of abnormality can be found by 1% of the Down syndrome and its severity is identical to the type 1 and type 2, or even less severity might be found. The cause of this type is that the chromosome does not split during the second division or the later times after the fertilization. That the non-division of the chromosome happens after the fertilization, only certain cells found abnormal. If the syndrome is not revealed by the blood test but it is still suspicious the skin biopsy shall be performed.
4. Partial trisomy 21: at the pair 21 chromosome only partial excessive chromosome is found and it is Down Syndrome Critical Region or DSCR. This is less common and it will never be found with the normal chromosomal test. Therefore, if the clinical feature is suspected Down syndrome but the number of chromosome is normal the molecular genetic analysis shall be further performed.
In general, if the Down syndrome children are found the chromosomal study shall be performed to determine the kind of abnormality. If the type of translocation is found the parental chromosomal study is to be performed. If found the one who is the carrier the family members of that side chromosome should be study in order for the proper genetics counselling.
Clinical Features
Children with Down syndrome are like other children. Their parents are usually informed by obstetrician or pediatrician at birth that their child is Down syndrome. The Down syndrome children have some physical appearances in common, for example, low birth weight, shorter-than-normal body length; when getting older they will have their height less than normal people, small head, flat occipital bone, flat face, flat nose, slant eye, epicanthial folds, small and low ears, narrow external auditory canal, high arch palate, maxillary hypophasia resulting in narrow oral cavity, tongue protuded, tooth growth lag and disorder teeth, short neck, thick skin at the back of the neck, umbilical hernia and constipation, broad hand, short fingers, clinodactyly due to small metacarpal bone (some cases this piece of bone vanished resulting in one joint of little finger), transverse palmar crease, wide gap between toe fingers 1 and 2, sandal gap, good temper and friendly.
Down syndrome children encounter speaking and language-using problems. They are usually slow speaking and unclear accent. The muscles in the mouth work improperly due to the soft muscles.
Sexual organ will usually not be fully growth in both male and female. Male will be sterile because he cannot produce sperms therefore no sexual activity (1 case reported for having children). The female is capable of pregnancy even the uneven period. If pregnant, her child has 50% chance to inherit down syndrome.
The Down syndrome children has neonatal polycythemia (hemoconcentration) at birth more often than other infants. Additionally the children will have jaundice for longer time and additional symptoms, i.e. hair fall, dry skin, and folliculitus may be found. However, it is not necessary to find these diseases in every down syndrome children and it has no relation with the severity of the mental retardation.
In the past, the severity of the down syndrome was between moderate and severe. In present, due to the development contribution the severity is less between little to moderate. This severity is even lessen when they get older.
Linguistic skill development is slower while social skill is better. Learning by seeing is better than by listening.
Abnormalities commonly found with the Down syndrome
1. Congenital heart disease and blood vessel abnormality; found by 40% - 60%
2. Endocrine gland and thyroid gland abnormality; found by 15% and the event of diabetes is 1:250.
3. Alimentary canal system; intestinal obstruction is found by 5%-12%.
4. Musculoskeletal system
- Hip joint disconnection or movement; found 6% in the 2 months to 10 years old.
- The movement of the joint of piece 1 (atlas) and piece 2 (axis) of the cervical spine which is found to be 10%-30%.
5. Haemopoietic system: Leukemia is found with 1%-2% which is higher than normal people by 10-20 times.
6. Eye abnormalities: found by 60%
- Cataract: 3%-15%
- Eyesight abnormality: 30%-70% (severe: 5%)
- Dacyocystitis: 20%
- Squint: 23%-44%
- Nystagmus: 15%
7. Ear and language disorders
- Hearing disorder: 75% the conductive hearing loss is also found.
- Serous otitis media (SOM) : 50%-70%
8. Nervous system
- Epilepsy: found by 14%
- Mental disorder: found by 22% such as worry, depress, unusual adaptation, pervasive developmental disorder, mental disorder, and anorexia nervosa.
- Behavioral problems often found such as non-cooperation, attention deficit hyperactivity disorder, impetuous, naughty, aggressive and self-attack.
- Alzheimers disease: found by 20%-30% after 40 years old.
- Premature aging, i.e. Alzheimer, cataract, and degenerative joint disease.
9. Delayed development and intellectual disability.
10. Urogenital system: 2 out of 3 of females will be sterile and all males are sterile which found that the testicles are not in the scrotum.
11. Skin problems: found by 10% the problems are bald head, hair fall, dry skin allergic sensitive, and skin stain.
12. Growth: often short and fat, about 30% will start to be fat in the childhood at 3 years old and 50% of the teenagers are also potential.
13. Teeth: tooth growth lag, some have disorder teeth, gum problem, periodontics or gnash
14. Sleeping problem: snore and breath pause.
15. Infection disease: cold, sinusitis, central ear problem, and pneumonia.
16. Self-antibody condition: thyroiditis, hair fall, diabetes, autoimmune hemolytic anemia, and rheumatoid.
Caring guide and capability rehabilitation
The aim of the Down syndrome children caring is to cure as per symptoms and correct the abnormalities so that these children can help themselves in daily life and spend their life close to the normal people. The cure used is holistic approach by inter-profession team.
1. Sanitary : many abnormalities can be found in the Down syndrome and illness is tendency and more often. The parent shall be dependent on the medical doctor at the very early state and follow the cure timely in order for the doctor for better cure and useful advice, for example, advice on genetics, family planning, risk of disease repetition, and prenatal diagnosis.
2. The Down syndrome can develop themselves if receive the suitable practice. The parent shall be informed about the importance of development enhancement and how to practice the child at home to reach the normal children.
3. Daily life: the Down syndrome shall experience the same as normal children do in their daily life. This requires the practice. The parent may bring the child to different places so that the child can meet with others and shall spend their life with others. They will learn to control themselves, have relation with others, follow the social rules, and benefit from social services.
4. Physical capability rehabilitations include:
- Medical rehabilitations such as speaking training, physical therapy, occupational therapy.
- Educational rehabilitation by Individualized Education Program: IEP
- Social rehabilitation such as activity of daily living skills, disability registration.
- Vocational rehabilitation
Recommendations
When found that the baby is down syndrome,
1.1 The acceptance from its parent is the most important however difficult and time taking. This may cause the child abandoned. The father may divorce the mother or the relatives on the father side may accuse the mother for the case. In fact, the disorder may come from the father side.
1.2 The down syndrome children will have the same stages of development as the normal children do, for example, lift the head before sitting, crawling, standing, and walking. However the development may delays which may be helped by the development enhancement. The children will have the full potential as they shall. They can help themselves in every day life, study together with others, and spend their life in the same society.
1.3 Therefore, the parents shall not feel hopeless. They should understand in the disability of their child and give him/her love and warmth, help their child, follow the medical advice and regularly practice their child to reach the best of his/her development.
1.4 Female down syndrome shall annually receive pelvic examination in order to check for the cervical cancer including breast examination.
1.5 Recommend on birth control and sterilization regarding the consent. Female down syndrome is capable of pregnancy and the child will be 50% chance to be down syndrome. Male will be sterile however some family may still need male sterilization.
1.6 Sexual education shall contain in the special education.
1.7 The down syndrome child with congenital heart disease shall be advised to prevent infective endocarditis. If dental medical is to be performed the antibiotics shall be given earlier.
1.8 In adult age, heart examination shall be performed because adults by 57% have mitral valve prolapse and 11% have aortic regurgitation.
2. Family planning for the family with down syndrome
The family planning for this case is very important and can be divided into 2 categories:
2.1 The parents with down syndrome children shall be advised about: 2
- Chance of repetition in the next child depending on the type of chromosome aberration.
- Prenatal diagnosis and options for the next child
- Different methods of temporary birth control until the next child readiness. The readiness depends on the family, usually 2-3 years, waiting for the down syndrome to grow and can do anything him/herself.
- If no more children is desire the permanent birth control shall be given.
2.2 Each down syndrome person shall be considered for birth control either temporary or permanent.
3. Prenatal diagnosis for the down syndrome
Prenatal diagnosis is the examination to determine if the baby in the womb has the genetic diseases such as down syndrome.
The prenatal diagnosis shall be performed on the following bases:
1. Mother is over 35 years old
2. Previously having a down syndrome child
3. Previously having a child with chromosome aberration.
4. Father or mother is a chromosome aberration carrier.
5. Having suspicion of down syndrome after the mothers blood test or ultrasound.
6. Mother has history of abortion for many times without knowing the real cause.
7. Mother ever has a retardation child without knowing the real cause.
8. Suspicion on disease which can be examine by molecular genetic technique.
Presently, the prenatal diagnosis for the down syndrome has 2 categories:
A. Screening the down syndrome baby in the womb, i.e. biochemical screening
test and ultrasound. These techniques are 50%-70% sensitive, not 100% certainty.
B. Prenatal diagnosis, i.e. Chorionic villi sampling and amniocentesis. These techniques will tell clearly about the down syndrome.
Therefore, genetic counseling shall be given to the couple who have high risk to give birth to a disorder child or some genetic diseases in order for the couple to better decision making and to avoid having the child with such diseases. However, there still are some limitations due to the diagnosis is the performed on the family problem basis. The diagnosis is to be performed in order to find some disease previously assumed. It cannot tell all abnormalities of the baby. The approach chosen depends on the information on risk and accuracy regarding ethics, morals and related laws.
4. Development enhancement
Development enhancement is the service for assist the child of 0-3 years to develop normal capabilities in accordance with his/her age or as best as existing potential. The education will be arranged according to ages. It includes necessary skill developments, self help and social skill as desire by parents.
Objectives of development enhancement
1. To have the child to develop him/herself to full potential and can help
him / herself.
2. To prevent problems, prepare the child to the quality adult with proper behavior and appropriate occupation.
3. To have the parents to know and apply to their child.
4. To make the family with good relation.
Goals of the development enhancement
1. General goal is to develop the skills for the children to live normally in a community as social members.
2. Specific goal to develop specific skills form easy to difficult and to response to the environment properly.
Development enhancement results
1. Skills in reading, mathematics, and language are developed.
2. Better adaptation and self help
3. Better accepted from community, able to participate in normal classes.
4. Behavioral problem and disability problem mitigation.
5. Better quality of life, better problem shooting, better working.
References
1. Noppawun Sriwongpanich. The Down syndrome. 2nd published, Bangkok, the agricultural cooperative of Thailand limited printing house, 2002.
2. Noppawun Sriwongpanich, Pat Rojmahamongkol. Intellectual Disability/Mental Retardation, In : Nichara Ruangdarakanon. Chakriya Theeranate, Rawiwan Rungpriwun, Tippawun Hunsakhunachai, Nittaya Kochaphakdee, Children behavior and development textbook, first published, Bangkok : Holistic Publishing, 2008 : 179 204.
