Developmental Delay and Learning Disability Flashcards
What is the most common genetic cause of developmental delay?
Down’s syndrome
1/600 pregnancies
How is Down’s syndrome screened for?
Combined test (10 weeks - 14 weeks + 1 day):
Serum screening - beta-HCG and PAPP-A
US screening - nuchal translucency
If later = quadruple test (14 weeks + 2 days - 20 weeks + 0):
- beta-HCG
- AFP
- Inhibin-A
- Unconjugated estriol (uE3)
List the possible genetic defects in Down’s syndrome
1) Trisomy 21 = 94%
2) Mosaicism = 2.4%
3) Translocations = 3.3%
NB 75% of these translocations are de novo errors
What is a trisomy 21?
Additional copy of an entire chr 21
In most cases it is maternally derived, through an error in cell division called non-dysjunction (can be during meiosis or a mitotic error)
What is partial trisomy 21?
When only a segment of chr 21 has three copies
What is mosaicism?
When the whole chromosome is triplicate but only a proportion of the cells are trisomic with the other cells being normal
What is translocation in Down’s syndrome?
Some of the genetic material from chr 21, usually from the long arm, is moved to chr 14 or 22, or from the long to the short arm of chr 21
What are some risk factors for Down’s syndrome? (2)
1) Inc maternal age
2) FH
What is typically the first feature noticed in Down’s syndrome?
Hypotonia
What are some general neonatal features of Down’s syndrome?
Hyper-flexibility
Hypotonia
Transient myelodysplasia of the newborn
What are the neonatal features of Down’s syndrome in the head?
Brachycephaly Oblique palpebral fissures Epicanthic folds Ring of iris speckles = Brushfield's spots Ears set low, folded or stenotic meatus Flat nasal bridge
What are the neonatal features of Down’s syndrome in the mouth?
Macroglossia
High arched palate
What are the neonatal features of Down’s syndrome in the hand?
Single palmar crease
Short little finger
In-curved little finger
Short broad hands
What are the neonatal features of Down’s syndrome in the feet?
Sandal gap between hallux and second toes
How may the heart and GIT be affected in Down’s syndrome?
Congenital heart defects
Duodenal atresia
What is transient myelodysplasia of the newborn?
= transient neonatal preleukaemic syndrome
Majority undergo remission
10% progress to myeloid leukaemia of Down’s syndrome
What screening should newborn’s with Down’s syndrome undergo?
Cardiac Feeding Vision Hearing Thyroid Haematological
What % of newborns with Down’s syndrome have a congenital heart defect? How should this be investigated?
50%
Often undetectable on prenatal US
Need echocardiogram
What should marked hypotonia or other feeding difficulties prompt in Down’s syndrome?
Radiographic swallowing
How is congenital cataracts checked for?
Red reflex
Why should a FBC be included in for newborns with Down’s syndrome?
Increased risk of transient myeloproliferative disorder, leukaemoid reaction and polycythaemia
How frequently do children with Down’s syndrome need review?
Annual checks of: Feeding assessment Bladder and bowel function Behavioural disturbance Vision and hearing
What are the most common cardiac abnormalities in Down’s syndrome? (6)
1) Atrioventricular canal defects
2) VSD
3) Isolated secundum atrial septal defects
4) Isolated persistent patent ductus arteriosus
5) Fallot’s tetralogy
6) Adults may develop mitral valve prolapse or aortic regurgitation
What ENT disorders are common in Down’s syndrome? (5)
1) 90% have hearing loss (conductive, sensorineural or mixed)
Inc risk of:
2) OM
3) Sinusitis
4) Pharyngitis
5) Obstructive sleep apnoea
What ophthalmological disorders are common in Down’s syndrome? (6)
1) Cataracts
2) Refractive errors
3) Strabismus
4) Nystagmus
5) Congenital glaucoma
6) Keratococonus
What GI disorders are common in Down’s syndrome? (9)
1) Oesophageal atresia or tracheo-oesophageal fistula
2) Duodenal atresia
3) Pyloric stenosis
4) Meckel’s diverticulum
5) Hirschsprung’s disease
6) Imperforate anus
7) GOR
8) Dental problems eg delayed and unusual patterns of eruptions, missing teeth
9) Coeliac disease
What orthopaedic disorders are common in Down’s syndrome?
1) Atlanto-axial instability
2) Hyperflexibility
3) Scoliosis
4) Hip dislocation
5) Patellar subluxation or dislocation
6) Foot deformities
What endocrine disorder is common in Down’s syndrome? (1)
Hypothyrodism
What neurological and psychiatric disorders are common in Down’s syndrome? (4)
1) Learning difficulties - range from severe to those with ‘low normal’ IQ
2) Behavioural problems
3) Seizures in 5-10%
4) In older - Alzheimer’s type picture develops in >60% of those over 60yrs
What haematological disorders are common in Down’s syndrome?
1) 12x greater risk of infection eg pneumonia due to impaired cellular immunity
2) Increased risk of acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) and acute megakaryoblastic leukaemia (AMegL)
3) Polycythaemia and transient myeloproliferative disorder (self-limiting type of leukaemia which regresses spontaneously by age 2 months)
What is a strabismus?
A squint
Misalignment of the eyes (eyes point in different directions)
Thus the retinal image is not in corresponding areas of both eyes
- Amblyopia in childhood
- Diplopia in adults
What is amblyopia?
Eye fails to achieve normal visual acuity
= Lazy eye
What is esotropia?
Inward-turning squint
What is exotropia?
Outward-turning squint
What are hypo- and hypertrophic?
Downward and upward turning squint
How common are squints?
1/15 children
Increased incidence in learning disability + brain damage
What is the cause of strabismus?
Can occur in otherwise normal children - most idiopathic
Rarer causes:
Cataract
Retinal disease / retinoblastoma
Glaucoma
What is infantile (congenital or essential) strabismus?
Common condition characterised by a squint in an otherwise normal infant with no refractive error
Early childhood strabismus common and usually settles by 4 months = this type is always intermittent
