Paeds genetics Flashcards
Down’s Syndrome is caused by
three copies of chromosome 21. It is also called trisomy 21
Dysmorphic features of down syndrome
Complications of down syndrome
Explain antenatal screening of down syndrome
The quadruple test is performed between 14 and 20 weeks gestation. It is identical to the triple test but also includes maternal blood for inhibin-A. A higher inhibin-A indicates a greater risk.
Antenatal testing of down syndrome
Management of down syndrome
Average life expectancy for down syndrome is
The average life expectancy is 60 years
There are some routine follow up investigations that are important for children with Down’s syndrome:
Regular thyroid checks (2 yearly)
Echocardiogram to diagnose cardiac defects
Regular audiometry for hearing impairment
Regular eye checks
Cystic fibrosis (CF) is an… genetic condition affecting which body parts?
Cystic fibrosis (CF) is an autosomal recessive genetic condition affecting mucus glands
CF is caused by…most common mutation is…this gene codes for…
- It is caused by a genetic mutation of the cystic fibrosis transmembrane conductance regulatory gene on chromosome 7.
- many variants of this mutation, most common delta-F508 mutation
- This gene codes for cellular channels, particularly a type of chloride channel.
The key consequences of the cystic fibrosis mutation are:
both parents are healthy, one sibling has cystic fibrosis and a second child does not have the disease, what is the likelihood of the second child being a carrier?
We know the child doesn’t have the condition, so the answer is two in three.
first sign of cystic fibrosis
Cystic fibrosis is screened for at birth with the
newborn bloodspot test.
If cystic fibrosis is not diagnosed shortly after birth it can present later in childhood with typical signs and symptoms…
recurrent lower respiratory tract infections
failure to thrive or
pancreatitis.
symptoms of CF
signs of CF
Causes of clubbing in children
There are three key methods for establishing a CF diagnosis that you should remember for your exams:
gold standard for confirming the CF diagnosis
sweat test
what does the sweat test test for in CF
chloride concentration
The diagnostic chloride concentration for cystic fibrosis is more than
more than 60mmol/l
common microbial colonisers in CF: which 2 most important to remember
Colonisation with…leads to a significant increase in morbidity and mortality in patients with CF
pseudomonas
Pseudomonas colonisation can be treated with
Pseudomonas colonisation can be treated with long term nebulised antibiotics such as tobramycin. Oral ciprofloxacin is also used.
Patients with cystic fibrosis take long term prophylactic…to prevent…infection
Patients with cystic fibrosis take long term prophylactic flucloxacillin to prevent staph aureus infection
management of CF
monitoring in CF
CF prognosis including potential consequences of CF in the long term
An increased risk…are the most serious long-term health problems for women with Turner’s syndrome
An increased risk of aortic dilatation and dissection are the most serious long-term health problems for women with Turner’s syndrome
Turner syndrome definition
Turner syndrome occurs when a female has a single X chromosome, making them 45 XO. The O referrs to an empty space where the other X chromosome should be. Life expectancy is close to normal.
Turner syndrome features
Turner syndrome associated conditions
Turner syndrome management
Which cardiac defects are associated with turner syndrome?
- Bicuspid valve
- aortic root dilatation and dissection
- coarctation of the aorta
Patau syndrome key features
Microcephalic, small eyes
Cleft lip/palate
Polydactyly
Scalp lesions
extra:rocker bottom feet
Patau syndrome definition
trisomy 13
Edward syndrome key features
Micrognathia
Low-set ears
Rocker bottom feet
Overlapping of fingers
Edward syndrome definition
Trisomy 18
Fragile X key features in males and females
black and white picture of asian kid
Fragile X definition
Fragile X diagnosis
- can be made antenatally by chorionic villus sampling or amniocentesis
- analysis of the number of CGG repeats using restriction endonuclease digestion and Southern blot analysis
Noonan syndrome definition
- male Turner’s’, Noonan syndrome is an autosomal dominant condition associated with a normal karyotype.
- defect in a gene on chromosome 12
Noonan syndrome features
Pierre robin syndrome features
- Micrognathia
- Posterior displacement of the tongue (may result in upper airway obstruction)
- Cleft palate
Prader Willi syndrome definition
genetic condition caused by the loss of functional genes on the proximal arm of the chromosome 15 inherited from the father. This can be due to a deletion of this portion of the chromosome, or when both copies of chromosome 15 are inherited from the mother.
Prader Willi syndrome features
Prader Willi syndrome management
William syndrome features
Starburst eyes (a star-like pattern on the iris)
Wide mouth with big smile
Friendly, extrovert personality
Short stature
Learning difficulties
Transient neonatal hypercalcaemia
Supravalvular aortic stenosis
William syndrome definition
William syndrome is caused by a deletion of genetic material on one copy of chromosome 7, resulting in the person only having a single copy of the genes on this deleted region (on the other chromosome 7). It usually the result of a random deletion around conception, rather than being inherited from an affected parent.
Cri du chat syndrome definition
chromosome 5p deletion syndrome
Cri du chat syndrome features
- Characteristic cry (hence the name) due to larynx and neurological problems
- Feeding difficulties and poor weight gain
- Learning difficulties
- Microcephaly and micrognathism
- Hypertelorism
