WHAT IS DOWN SYNDROME?
- A syndrome is a condition formed by a pattern of characteristics occurring together in a person.
- Named after Dr. Langdon Down who reported the similarities characteristics in children with intellectual disability in 1866.
- Most common identifiable cause of intellectual disability.
- Frequency : 1 in every 660 babies born with Down Syndrome.
- Estimated around 1000 newborns in Malaysia are affected with Down Syndrome each year.
- Flat nasal bridge
- Eyes may have an upward and outward slant
- Small ears and low set
- Small and stubby hands
- Single crease across the palm
- Wide gap between toes
- Low muscle tone (hypotonia)
- Delay in achieving milestones
Common Medical Complications
- Cardiac malformations (40%)
- Gastrointestinal malformations (12%)
- Auditory Deficits (50 – 70%)
- Respiratory problems
- Epilepsy (5%)
- Hypothyroidism (16%)
- Leukamia (1%)
- Alzheimer disease
Causes of Down Syndrome
- Caused by chromosomal abnormalities
- Three types
- Each type involves extra chromosome 21
– 1. Standard trisomy (95%)
– 2. Translocation
– 3. Mosaic (2%)
- Found in the nuclues of a cell
– Deoxyribonucleic Acid (DNA)
- Exist in pairs
- One copy of each chromosome inherited from mother and the other from father.
- 2 types of chromosomes :
– not involved in sex determination
– 22 pairs in human somatic cells
2. Sex Chromosomes
– determines sex of baby
– Female -XX Male – XY
- To identify the number and structure of chromosomes in cell
- Trisomy means three copies of chromosomes
- 95% of cases involves extra copy of chromosome 21 in every cell in the body
- Result of faulty distribution of chromosomes in either the mother’s egg or father’s sperm
- A process of cell division to form reproductive cells- sperm & ovum
- Non-disjunction in Meiosis I & II
- An extra copy of chromosome 21 is attached to another chrosome
- Either parent may be a healthy carrier of a balanced translocation
- May occur by chance (spontaneously) in the child or may be inherited (“unbalanced”)
- Parental chromosomes should be analysed
- Mixture of cells with 2 copies of chromosome 21 (normal) and some cells with trisomy 21
- Resulted from error of cell division after conception
- Number of trisomy cell affects the severity of the characteristics presented.
Maternal Age Risk
- Refers to the relationship between a women’s age and risk of having child with Down Syndrome
- Women over the age of 35 is at greater risk
- Chorionic Villous Sampling (CVS)
– Between 11-14 weeks of gestation
– 1% or 1 in 100 risk of miscarriage
– Bewteen 16-18 weeks of gestation
– 0.5% or 1 in 200 risk of miscarriage
- Definition : A communication process which deals with the risk of developing or transmitting a genetic condition.
- Goal : To provide accurate information and assist client to make fully informed decision.
Reasons for Genetic Counselling
- To obtain information
– about a genetic condition
– about genetic testing
- When there is family history of inherited diseases
- Past history of infertility, pregnancy losses, still births and early infant deaths.
- Concern about
– the effects of drugs and infections during early pregnancy
– pregnancy for older parents
What happens in Genetic Counselling?
- Determine client’s needs and intentions
- Establishment of diagnosis
- A family tree / pedigree will be drawn for the family
- A physical examination may be required
- Relevant tests to clarify the diagnosis
- Estimation of recurrence risk
- Burden of care
- Reproductive options
- Communication of relevant information
- Provision of long term support
- Support Group
- Integration into normal society
- Regular health monitoring