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Child health > SYNDROMES > Flashcards

SYNDROMES Flashcards

1
Q

Explain the cytogenetics of Down Syndrome.

Risk factors?

A

Extra chromosome 21 may result from:
meiotic non-disjunction
translocation
mosaicism

94% are meiotic non-disjunction.
Pair of 21 chromosomes fails to separate so that one gamete has 2 chromosome 21s. If its fertilised, it results in trisomy 21.

Translocation (5%) is when the extra chromosome 21 is joined onto another chromosome (Robertsonian translocation). Usually 14, but also 15, 22, 21.

In mosaicism (1%), some cells are normal, some have trisomy 21. Usually from mitotic non-disjunction.

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2
Q

What are the obstetric risk factors for Down syndrome?

A

If previous baby with Down syndrome , risk of recurrence is 1 in 100.

If one parent has Down syndrome, the chance of the child having it is 50%

Incidence of meiotic non-disjunction is related to maternal age.

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3
Q

What are the clinical features of Down syndrome?

A 
Facies
Single palmar crease
Pronounced "sandal" gap betweem the big and second toe.
Incurved 5th finger.
Hypotonic.
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4
Q

What are the diagnostic investigations for Down syndrome?

A

ANTENATAL

At 10-14 weeks - blood test and US (nuchal thickness)
Chorionic villus sampling can be done from 11-14 weeks.
Amniocentesis from 15 weeks. Both are diagnostic.

POSTNATAL
Blood test:
rapid FISH (fluorescent in situ hybridisation)

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5
Q

What are the associated problems in Down syndrome?

A 
Risk of:
Hypothyroidism
Impairment of vision and hearing.
Cataracts
Increased risk of infection
Leukaemia (1%)
Developmental hip dysplasia
Eczema
Atlanto-axial instability.
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6
Q

Describe the cranio-facial appearance of someone with Down Syndrome.

A 
Round face
Flat nasal bridge
Epicanthic folds
Small mouth and protruding tongue
Small ears
Flat occiput
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7
Q

Associated anomalies in Down syndrome?

A

Congenital heart defects
Duodenal atresia
Hirschprung disease

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8
Q

What are the long-term problems in Down syndrome?

Clearly involves a multidisciplinary team

A

Delayed motor milestones.
Learning difficulties.
Increased susceptibility to infections.
Secretory otitis media and hearing impairment.
Visual impairment from cataracts, myopia.
Higher risk of leukaemia and solid tumours.
Risk of atlanto-axial instability.
Increased risk of hypothyroidism and coeliac disease.
Epilepsy
Alzheimer’s disease

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9
Q

Cytogenetics of Turner’s syndrome

A

Presence of only one X chromosome
Or
Deletion of the short arm of one of the X chromosome

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10
Q

What are the clinical features of Turner’s syndrome

A 
Lymphoedema of hands and feet as neonate - may persist
Short stature
Widely spaced nipples
Webbed neck
High arched palate

Delayed puberty
Primary amenorrhea
Infertility

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11
Q

What are the associated problems with Turner’s syndrome

A

Heart problems
bicuspid aortic valve (15%)
coarctation of the aorta (5-10%)

Kidney problems and ureter malformations (horseshoe kidney, rotational anomalies, obstructions)

Hypoplastic ovaries - amenorrhoea and infertility

Osteoporosis and pathological fractures

Increased incidence of autoimmune disease (thyroiditis) and Crohn’s

Pigmented naevi

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12
Q

Investigations for Turner’s

A 
Karyotyping is diagnostic
Hypergonadotropic hypogonadism (low oestrogen and androgens but high FSH and LH)
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13
Q

Management options for Turner’s

A

Growth hormone replacement (SC injections)

Oestrogen replacement for development of secondary sexual characteristics at the time of puberty (infertility remains, however) - between 12-14 yrs

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14
Q

What is the role of genetic counselling?

A

Support
Education

Diagnosis - thorough examination, history, investigations

Helps understand situation, make decisions about risks of diseases - RISK estimation

Provide greater autonomy in reproductive decisions

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15
Q

List some common dysmorphic features associated with syndromes (incomplete)

A

malformation - spina bifida, cleft lip/palate

disruption - amniotic membrane rupture causing limb reduction defects

Small ear with overfolded helix
Fifth-finger clinodactyly (incurving of the fifth finger - Down’s)
Syndactyly (fusion) of the fingers or toes

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16
Q

Key dysmorphic features of fetal alcohol syndromes

A 
Dysmorphism:
Thin upper lip
absent philtrum
Down-slanting, short palpebral fissures
Narrow, receding forehead
Short nose
Hypertelorism
Epicanthal folds
Receding chin
Microcephaly
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17
Q

Neurodevelopmental problems associated with fetal alcohol syndrome

A

Holoprosencephaly (forebrain fails to divide into hemispheres)

Structural - microcephaly, cerebellar hypoplasia, agenesis of corpus callosum

Impaired fine motor skills
Neurosensory hearing loss
Poor eye hand coordination

Effects:
Hyperactivity
Intellectual disability (learning disabilities, memory and reasoning deficits, and impaired language development)

Problems in social interactions and school performance

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18
Q

What is fragile X syndrome and features

A

X linked dominant
Unstable Trinucleotide repeat disorder

Features in females vary, whereas fully expressed in males

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19
Q

Learning difficulties in fragile X

A

After trisomy 21, fragile X syndrome accounts for the most cases of intellectual disability due to a genetic cause
Delayed language development and autism

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20
Q

Dysmorphic features of fragile Xq

A

large low set ears, long thin face, high arched palate
macroorchidism

X-tra large → big ears, testes, face

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21
Q

IQ score range in Down syndrome

A

25-70

22
Q

Managing the long-term problems in Down syndrome (MDT)

A

Refer for detailed cardiac assessment, hip US, audiology

Genetic counselling if the karyotype shows a translocation

Put in contact with a support organization (eg. Down Association)

Long-term MDT follow up lead by a paediatrician. Include physiotherapist for tone and posture

Test TFT annually
Refer for audiology and ophthalmic assessment 1-2 yearly

23
Q

What is a sequence

A

a pattern of multiple abnormalities occurring after one initiating defect

Potter syndrome is an example of a sequence in which all abnormailiteis may be traced to one original malformation – renal agenesis

24
Q

What is a syndrome

A

a particular set of multiple anomlaies occurs repeatedly in a consistent pattern and there is a known or thought to be common underlying casual mechanisms

often associated with moderate or severe cognitive impairment

may be due to:
chromosomal defects
single gene defect
exposure to teratogen

25
Q

dysmorphism in noonan syndrome

A

Males and females. Similar phenotype to Turner.

Facies
Mild learning difficulties
Short webbed neck
Pectus excavatum
Short stature
Congenital heart disease (pulmonary stenosis or ASD)
26
Q

dysmorphism in william syndrome

A 
Short stature
Characteristic facies
Transient neonatal hypercalcaemia
Supraventricular aortic stenosis
Mild to moderate learning difficulties
27
Q

Dysmorphism in prader willi syndrome

A 
Facies
Hypotonia
Neonatal feeding difficulties
FTT in infancy
Obesity in later childhood
Hypogonadism
Developmental delay
Learning difficulties
28
Q

Dysmorphism in Patau syndrome

A 
Trisomy 13
Structural defect of brain
Scalp defects
Microphthalmia
Cleft lip + palate
Polydactyly
Cardiac and renal malformations
29
Q

Dysmorphism in Edwards syndrome

A

Trisomy 18

Low birthweight
Prominent occiput
Small mouth and chin
Short sternum
Flexed, overlapping fingers
Cardiac and renal malformations
30
Q

Mode of inheritance of Duchenne Muscular Dystrophy

A

X-linked recessive
1/3 are new mutations (deletion of short arm of X chromosome at xp21 site)

Codes for dystophin (absence leads to myofibre necrosis)

Affects all men and homozygous women

31
Q

Main Clinical features of DMD

A

Developmental delay: late walking and speech delay

Early: boys have difficulty rising from the floor.
9 years: early loss of ambulation. Slower than peers
Mount stairs one-by-one. Run slowly

Cardiomyopathy
30% have non-progressive mild learning disability.

Average age of diagnosis: 5.5yrs

32
Q

Additional signs in DMD

A 
Waddling lordotic gait
Calf pseudohypertrophy (replacement by fat and fibrous tissue)
Weakness in limb girdles (Gower's sign)

Sparing of facial, extraocular and bulbar muscles
Language delay
Scoliosis

33
Q

Screening tests for DMD

A

neonatal screening test: serum creatinine phosphokinase markedly elevated

Serum creatinine kinase also grossly elevated.
Genetic testing often enough for diagnosis.

34
Q

Prognosis of DMD

A

Death from cardiorespiratory failure or infection by early 20s

35
Q

management of DMD (preventative)

A

Genetic counselling (X-linked recessive)

Exercise for power and mobility (delay scoliosis)

Passive stretching and night splints to prevent ankle contracture
Lengthening of Achilles tendon? For ambulation

Attention to good sitting posture (scoliosis)

Parent self-groups for information and support

Ambulant children: corticosteroids to preserve mobility and prevent scoliosis (prednisolone 10 days each months)

36
Q

Management of scoliosis in DMD

A

Truncal brace
Moulded seat
Surgical insertion of metal spine rod

37
Q

Late life management of DMD

A

Respiratory aids (CPAP) for nocturnal hypoxia secondary to weak intercostal muscles.

Improves quality of life

38
Q

Types of neurofibromatosis

A

Group of conditions where tumours grow on the nervous system. 3 types:

NF1 - chromosome 17. light brown spots of the skin, freckles in armpit and groin. Small bumps within nerves

NF2 - chromosome 22. Hearing loss, cataracts at young age, balance problems, flesh coloured skin flaps and muscle wasting

NF3 - Schwannomatosis

39
Q

Genetics of neurofibromatosis

A

Autosomal dominant
Highly penetrant
1/3 new mutations

Tumours generally non-cancerous

40
Q

Diagnostic criteria of NF1

A

2 or more of these criteria:
6 or more cafe-au-lait spots (>5mm before puberty, >15mm after)

> 1 neurofibroma (firm overgrowth of a nerve)

Axillary freckles

Optic glioma which may cause visual impairment

1 Lisch nodule (hamartoma of the iris)

Bony lesions from sphenoid dysplasia, which can cause eye protrusion.

1st degree relative with NF

41
Q

Diagnosis of NF 2

A

Less common than NF1.
1 major and 2 minor criteria:
Major:
Unilateral vestibular Schwannoma & 1st degree relative with NF2

Bilateral vestibular Schwannoma

Minor:
Meningioma
Schwannoma
Ependymoma
Glioma
Cataract
42
Q

Genetics of tuberous sclerosis

A

Dominant
70% are new mutations in TSC1 and TSC2 genes.
They code for hamartin and tuberin respectively (tumour suppressor genes)

1 in 9000 live births

43
Q

Diagnosis of tuberous sclerosis

A

Definite: 2 major features with 2 or more minor

Possible.. 1 major feature or 2 minor

44
Q

Major features of Tuberous Sclerosis

A 
Facial angiofibromas
Ungul fibroma
Hypomelanotic macules (>3)
Shagreen patch
Subependymal nodules
SubE giant cell astrocytoma
Retinal nodular haematoma
Cardiac rhabdomyomata

(basically affects brain, skin, heart, kidney, eye, lung)

45
Q

Minor features of Tuberous sclerosis

A 
Pits in dental enamel
Rectal polyps
Bone cysts
Non-renal haematoma
Retinal achromatic patch
Cerebral white matter migration tracts
Gingival fibromas
Confetti skin lesion
Multiple renal cysts
46
Q

Clinical features of NF1

A

Cutaneous features more evident after puberty
Spectrum of mild-to-severe

Neurofibromata in any peripheral nerve including cranial nerves (symptoms if they occur where the nerve passes through a bony foramen)

Visual or auditory impairment if 2nd or 8th cranial nerves are compressed

Menalencephaly with learning difficulties and epilepsy sometimes

47
Q

Features of NF2

A

Bilateral acoustic neuromata are predominant feature

Deafness and sometimes a cerebellopontine angle syndrome with a facial (7th) nerve paresis and cerebellar ataxia

There can be an overlap between the features of NF1 and NF2. Both can be associated with endocronological disorders

48
Q

Tuberous sclerosis features

A

Cutaneous:
depigmented “ash-leaf” shaped patches which fluoresce uner UV light
Shagreen patches (roughened patches of skin usually over lumbar spine)
Adenoma sebaceum in a butterfly distribution over the bridge of the nose and cheeks

Neurological:
Infantile spasms and developmental delay
Epilepsy (often focal)
Intellectual impairment

Severe learning difficulties and often autistic features when older

49
Q

Long term health problems with NF

A 
phaeochromocytoma
Pulmonary HTN
Renal artery stenosis with HTN
Skeletal dysplasia
Cognitive impairment
50
Q

Long term health problems with tuberous sclerosis

A

Subungal fibromata (beneath the nails)
Ophthalmological haematomata
Cardiac rhabdomyomata (usually resolve in infancy)
Polycystic kidneys
Gliomatous change can occur in brain lesions
Symptomatic epilepsy

Child health (51 decks)

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