Genetic Conditions Flashcards
How common is Down’s syndrome?
1 in 1000
What is the most common aetiology for DS?
Meiotic non-dysjunction
94%
What other aetiologies of DS are there?
Translocation 5%
Mosaicism 1%
What is Robertsonian translocation?
Translocation from Chr21 to Chr14
What organs are affected in DS? (7)
Heart Eyes Ears Thyroid Pancreas - DM Gut Brain
What are the physical features of DS?
Upslanting palpebral folds
Single palmar crease
Wide sandal gap
What are the cardiac defects in DS? (4)
Endocardial cushion defect 40%
VSD 30%
ASD 10%
ToF 5%
Often congenital
What are the later complications of DS?
Learning difficulties Subfertility Hypothyroidism Alzheimers by 40yrs Atlantoaxial instability
What things do you screen for at birth in DS?
Heart defects DM Coeliac Eyes Ears
What do you screen yearly in DS?
Bladder and bowel function
TFTs
Eyes
Ears
What GI issues may be present in DS?
Duodenal atresia
Hirschsprungs
Why do all DS babies need Che analysis?
Translocation = need parental Chr study
Free trisomy = no need
What is the combined screen?
Nuchal translucency
hCG
PAPP-A
What is the quadruple test?
hCG
Oestriol
AFP
Inhibin-A
What is the risk of having a baby with DS if >40yrs?
1 in 100
What is the risk of having a baby with DS if >44yrs?
1 in 50
What is the triad of features for ASD?
Impairment of social interaction
Impairment of communication
Restrictive, repetitive and stereotyped patterns of behaviour
What is different about Asperger’s?
Tend to have above average intelligence
Understand that they do not fit in
What is the prevalence of ASD?
1%
What health problems are associated with ASD?
Learning difficulties
Seizures - 15%
Vision/hearing impairment
What is the management of ASD?
MDT approach
Speech and language to help with language
Education of parents and school
ASD team if regression of language <3yrs old
When must ASD have presented by?
3yrs
What should you do if a child presents with language regression <3yrs old?
Refer to ASD team
What causes 50% of childhood blindness?
Genetic causes eg. DS, CHARGE association
What are some congenital cause of blindness? (5)
Cataracts Albinism Retinal dystrophy Retinoblastoma Congenital infection eg. CMV, rubella
What are some antenatal causes of blindness? (4)
Retinopathy of prematurity
Hypoxic-ischaemic encephalopathy
Cerebral damage
Optic nerve hypoplasia
What are some postnatal causes of blindness? (3)
Trauma
Infection eg. ophthalmic HSV
JIA -> iritis
What is Isolated Delayed Visual Maturation?
No underlying pathology
Rapid and full development between 3-6m
Associated with motor delay
What is DSM with cerebral visual impairment?
Infants appear blind
Vision improves over years but may remain impaired
What is DSM with ocular disease?
Congenital ocular disease (eg. cataracts) interferes with development
Vision improves but some residual deficit
What two syndromes are associated with sensorineural deafness?
Ushers syndrome = SN deafness + retinitis pigmentosa
Waardenburg syndrome = SN deafness + pigmentation abnormalities
What is the most common childhood hearing problem?
Glue ear
What is the management of chronic glue ear?
Grommet insertion
How common are squints?
1 in 20
To what age is it common for newborns to have transient squints?
3 months
If continue, refer
What is the most common cause of a squint?
Failure of development of binocular vision
What are some refractive errors causing squints?
Myopia
Hypermetropia
Stigmatism
What are two serious causes of squints?
Cataracts
Retinoblastoma
What is esotropia?
Eye turns inwards
What is exotropia?
Eye turns outwards
What is hypotonia?
Eye turns downwards
What is hypertrophia?
Eye turns upwards
What are the two types of squint?
Paralytic
Non-paralytic
What causes a non-paralytic squint?
Often refractive errors
Easily correctible with glasses
What are the features of non-paralytic squints?
Angle of deviation does not vary with direction of gaze Often esotropic (inwards`0
What causes paralytic squints?
Damage to extraocular muscles or their nerves
May indicate space-occupying lesion
What are the features of paralytic squints?
Angle of deviation varies with direction of gaze
Diplopia
What are the parts of a squint examination? (9)
Visual acuity Eye movements Pupil response Accommodation Corneal light reflex Red reflex Cover test Alternate cover test Fundoscopy
What is the management of a squint?
Correction of refractive errors
Eye patch to prevent amblyopia if <8yrs old
Follow-up at 6wks and annually until 10yrs old
What will paralytic squints need?
Surgery
What is Fragile X syndrome?
X-linked CGG trinucleotide expansion
>200 copies (normally <50)
Can females be affected by Fragile X syndrome?
Not fully
Large number have learning difficulties
What are the features of Fragile X syndrome? (7)
Learning difficulties Long face Macrocephaly Macro-orchidism Mitral valve prolapse Autism Hyperactivity
What are the characteristic facial features of Fragile X syndrome? (4)
Long face
Large everted ears
Prominent mandible
Large forehead
What are the features of Patau syndrome? (4)
Microcephalic
Cleft lip
Polydactyly
Scalp lesions
What are the features of Edward’s syndrome? (4)
Micrognathia
Low-set ears
Rocker-bottom feet
Overlapping fingers
What are the features of Noonan syndrome? (4)
Webbed neck
Pectus excavatum
Short stature
Pulmonary stenosis
What are the features off Pierre-Robin syndrome? (3)
Micrognathia
Posterior displacement of tongue
Cleft palate
What are the features of Prader-Willi syndrome? (3)
Hypotonia (neonatal)
Hypogonadism
Obesity
What are the features of William’s syndrome? (5)
Short stature Learning difficulties Overly freindly Transient neonatal hypercalcaemia Supravalvular aortic stenosis
What are the features of Beckwith-Wiedermann syndrome? (3)
Fetal macrosomia
Large tongue
Infant becoming hypoglycaemic
What are the features of Turner’s syndrome?
Short stature Webbed neck Wide-spaced nipples Neonatal lymphoedema Primary amenorrhoea
What is the karyotype of Turner’s syndrome?
45 XO
What heart defects are common in Turner’s syndrome?
Bicuspid aortic valve
Coarctation of the aorta
What is the management of Turner’s syndrome?
GH therapy
Oestrogen replacement - allows development of secondary sexual characteristics
How is Turner’s syndrome affected by parental age?
Increase with increased paternal age
Decreases with increased maternal age
How common in Turner’s syndrome?
1 in 2500 females
When should you consider Turner’s syndrome?
Any girl with short stature or primary amenorrhoea
What is the karyotype of Klinefelter’s syndrome?
47 XXY
When is Klinefelter’s syndrome usually diagnosed?
Investigations regarding male infertility
Single most common cause of hypogonadism
What is the presentation of Klinefelter’s syndrome?
Tall stature
Gynaecomastia
Hypogonadism
Infertility - azoospermia
