genetics Flashcards
Q1: Abbey is an 8 year old girl with Down’s Syndrome
She was diagnosed with Down’s Syndrome antenatally.
What antenatal screening tests are available to predict the risk of Down’s Syndrome?
- First trimester maternal beta-hCG
- PAPP-A blood levels
- combined with maternal age
- raised fetal nuchal translucency at ultrasound scan at 20 weeks’ gestation
If screening tests show a high risk of Down’s Syndrome what diagnostic tests are offered?
chorionic villus sampling or amniocentesis genetic testing
List three facial features observed in patients with Down’s Syndrome
- prominent epicanthic folds
- upwards slanting palpebral fissures
- Brushfield spots on the iris
- protruding tongue
- small mouth
- flat nasal bridge
- low set ears
List three other clinical features that you might find on examination
- generalised hypotonia
- short neck with excess skin at nape of the neck
- brachycephaly
- single palmar crease
- short hands and fingers
- sandal toe gap in feet
- short stature
Abbey has a congenital heart defect.
What is the most common congenital heart defect in children with Down’s Syndrome?
atrioventricular septal defect
She also has had severe constipation since birth.
What underlying condition is more common in children with Down’s Syndrome?
Hirschsprung’s disease
Q2: A 3 year old boy presents with an afebrile generalised tonic clonic seizure. On further questioning he was born at term via normal delivery, there were no neonatal complications.
His parents have had concerns about his development. He walked at 20 months. He said his first words at around the same time and now says a few words only. His parents think he can understand more than he can express. They have concerns about his interaction; he sometimes but not always gives eye contact and he doesn’t interact with the other children at nursery. He is ‘constantly on the go’ and they have noticed that when he is excited, he flaps his hands.
By what age would you expect a child to be able to walk independently?
18 months
Name two causes of delayed gross motor development
- cerebral palsy
- Duchenne muscular dystrophy
By what age would you expect a child to say 1-3 words with meaning?
12 months
By 2yrs how many words would you expect a child to have?
50 words
phrases of 2-3 words
By what age would you expect a child to have clear and fluent speech?
4 years
Investigations for global developmental delay reveal a diagnosis of Fragile X Syndrome.
What facial features can you observe in the picture of a child with Fragile X Syndrome below?
- long and narrow face with prominent forehead and chin
- large ears
What other features may they have?
- relative macrocephaly
- hypotonia and joint hyperlaxity
- flexible flat feet
- testicular enlargement over 8yrs
<strong>Developmental delay</strong> (including delay in motor and language milestones), intellectual disability and learning disabilities are the most salient clinical features of Fragile X syndrome.
They often have features of ADHD, anxiety, ASD, including hyperactivity, inattention, gaze aversion and stereotypic movements, such as hand flapping, hyperarousal, social anxiety, unusual speech patterns.
10-20% of boys with Fragile X syndrome develop <strong>seizures</strong>, the risk of seizures is highest in childhood, peak incidence 6 months to 4 years. Most are simple or complex partial seizures, including benign childhood epilepsy with centrotemporal spikes, are relatively easy to control and often spontaneously remit during childhood.
How is Fragile X syndrome diagnosed?
based upon detection of an alteration in the fragile X mental retardation gene (FMR1 gene)
