Down syndrome

Question 0

Causes

Answer 0

95%-an extra copy of chromosome 21.
occurs in the developing foetus resulting in the child being born with 47 chromosomes in each cells instead of 46.
This changes normal development of body and brain

Question 1

Definition of Down Syndrome

Answer 1

A genetic syndrome relating to an abnormality associated with chromosome 21. The syndrome comprises several specific physical add psychological features and an increased risk of medical complications

Question 2

Risk Factors

Answer 2

 Increased risk with increasing age of mother.

 Previous birth of a baby with DS.

Question 3

Epidemiology

Answer 3

 The most common genetic disorder causing intellectual disability.  DS occurs in approximately 1 in 1000 live births.
 Incidence increases with the mother’s age, rising from a risk of one in 2000 at 20 to one in 25 at 45 years of age. There is a similar gender ratio.

Question 4

pathophysiology

Answer 4

 Each cell in the body normally has 46 chromosomes (23 pairs, with one of each pair from mother and one from father). Each chromosome is organised into hundreds of genes.
 Abnormal cell division during the formation of an egg or sperm results in an additional copy of chromosome 21 and a total of 24 chromosomes from either mother or father.
 Therefore after fertilization with a sperm or egg with 23 chromosomes the resulting embryo contains 47 chromosomes.
 This results in malformations and developmental abnormalities. Many foetuses spontaneously abort.

Question 5

clinical Features

Answer 5

Common physical features may include-
 Facial- upward slant to eyes, small ears, flatter facial profile than usual, white spots in iris of eyes
 Short neck
 Low muscle tone, loose ligaments
 Small hands and feet
 Short stature
Delayed motor development and varying levels of intellectual disability include -
 Delay in motor milestones e.g. sitting, standing, walking, and in fine motor skills
 Delay in acquiring spoken language but socially responsive
 Mild to moderate cognitive impairment (10 between 40 and 70). Cognitive impairments are more obvious in older childhood because intellectual ability develops more slowly than normal. Autism and attention deficit disorders present more commonly in these children.

Question 6

Associated health conditions may include -

Answer 6

Congenital heart defects, hearing loss, eye problems, gastrointestinal problems, thyroid dysfunction, low resting metabolic rate and increased risk of weight gain, musculoskeletal problems associated with hypotonia

Question 7

Diagnosis- b4 birth and after birth

Answer 7

Before birth -
 Screening through blood tests and ultrasound tests.  Diagnostic testing with amniocentesis for older women
After birth - clinical observation combined with blood test to confirm DS

Question 8

interdisciplinary management

Answer 8

 Routine monitoring of possible medical conditions starting in infancy e.g. eye and hearing, heart disease, diabetes, hypothyroidism  Monitoring and treatment of mental health disorders such as depression in later life
 Surgery for heart defects
 Information and support for parents along with genetic counselling

Question 9

Prognosis

Answer 9

 Currently the average life expectancy is mid-fifties. Prognosis is affected by effective management of medical conditions associated with DS.
 Since 1970s prognosis for a productive and positive life has improved with more educational opportunities and supported employment.

Question 10

Differential Diagnosis

Answer 10

Other chromosomal abnormalities such as Prader-Willi syndrome