Aetiology and syndromes Flashcards
Clinical features of Usher’s syndrome
Retinitis pigmentosa
Congenital deafness
Vestibulocochlear ataxia
LD in 23% of cases
Psychosis in 15% of cases
Behavioural features of Fragile X syndrome
Shy
Gaze avoidant
Social anxiety
Hyperactive
ASD in 10%
Behavioural features of Prader-Willi syndrome
Insatiable appetite and food obsession
Skin picking
Impulsive
Aggressive
OCD
Behavioural features of Smith-Magenis syndrome
Hyperactive
Impulsive
Aggressive
Stereotyped behaviours e.g. self hugging
Self injuring behaviour
Behavioural features of Williams syndrome
Affectionate
Inattentive
Anxiety disorders
Phobias
Behavioural features of Cornelia de Lange syndrome
Self injuring behaviour
Behavioural features of Lesch-Nyhan syndrome
Severe self injuring behaviour
Behavioural features of velo-cardio-facial syndrome
Psychosis
Behavioural features of Rett syndrome
Stereotyped hand movements
Reduced interest in play in early years
ASD type symptoms
Behavioural features of Angelman syndrome
Puppet like gait
Laughing often
Attraction to water
Behavioural features of cri du chat syndrome
Inappropriate laughter
Cat like cry in infancy
Behavioural features of sanfilippo syndrome
Sleep disturbances
Impulsivity
Most common genetic cause of LD
Down’s syndrome
Incidence of Down’s syndrome
1 in 1000 live births
Incidence of Down’s syndrome in women <30
1 in 2500
Incidence of Down’s syndrome in women >40
1 in 80
Incidence of Down’s syndrome in women >45
1 in 32
Three genetic forms of Down’s syndrome
Full trisomy (non-disjunction)
Robertsonian translocation
Mosaic Down’s syndrome
Percentage of cases of Down’s syndrome caused by non-disjunction
92-95%
Percentage of cases of Down’s syndrome caused by Robertsonian translocation
2-4%
Percentage of cases of Down’s syndrome caused by mosaicism
1-2%
Facial features of Down’s syndrome
Upward slanting palpebral fissures
Flat wide nasal bridge
Protruding tongue
Small mouth
Close set eyes
Brushfield spots
Epicanthic folds
Low set ears
Most common cardiac defect in people with Down’s syndroem
AVSD
Non-facial physical features of Down’s syndrome
Hypotonia
Short stature
Overweight
Single palmer crease
Sandal gap
Undescended testicles in 20%
Physical comorbidities common in Down’s syndrome
Congenital heart disease
Testicular cancer
ALL
Oesophageal atresia
Hirschsprung disease
Umbilical and inguinal hernias
Poor eyesight - myopia, strabismus
Poor hearing - otitis media, sensorineural deafness
Hypothyroidism
Diabetes
Epilepsy
Percentage of people with Down’s syndrome with a congenital heart defect
40%
Average IQ of someone with Down’s syndrome
50
Incidence of Fragile X syndrome
1 in 3000
Most common inherited cause of LD
Fragile X syndrome
Triplet repeat seen in Fragile X syndrome
CGG
Gene affected in Fragile X syndrome
FMR1
Learning disability seen in women with Fragile X syndrome
Mild
Learning disability seen in men with Fragile X syndrome
Moderate/severe
Physical features of Fragile X syndrome
Large head
Large ears
Long, narrow face
Short stature
Macro-orchidism
Hyperflexible joints
Percentage of patients with Fragile X syndrome who have seizures
20-25%
Incidence of Turner’s syndrome
1 in 2000 to 1 in 5000 live born females
Percentage of conceptions with Turner’s syndrome which end in spontaneous abortion
99%
Physical features of Turner’s syndrome
Short stature
Low hairline
Webbed neck
Low set ears
Broad chest
Widely spaced nipples
Congenital malformations associated with Turner’s syndrome
VSD
Coarctation of the aorta
Behavioural features of Turner’s syndrome
Distractibility
Poor social skills
Poor self esteem
No LD
Incidence of triple X syndrome
1 in 1000 live born females
Percentage of people with triple X syndrome who have mild LD
60-70%
Psychiatric comorbidities seen in triple X syndrome
Anxiety
Possible association with schizophrenia
Incidence of Klinefelter’s syndrome
1 in 500 to 1 in 1000 live born males
Physical features of Klinefelter’s syndrome
Infertility
Sparse body hair
Hypogonadism
Gynaeocomastia
LD seen in Klinefelter’s syndrome
Skewed distribution
Median IQ 90
Most people have IQ in range 60-70
Behavioural features of Klinefelter’s syndrome
Poor school performance
Introversion
Lack of assertion
Incidence of XYY
1 in 1000 live born males
Behavioural features of XYY
Often associated with behavioural problems
Chromosome affected in Prader-Willi syndrome
15
Parental chromosome responsible for Prader-Willi syndrome
Paternal
Incidence of Prader-Willi syndrome
1 in 10000 to 1 in 25000 live births
Features of Prader-Willi syndrome in infancy
Hypotonia
Lethargy
Poor feeding and failure to thrive
Breech birth
Sleepiness
Characteristic features of Prader-Willi syndrome in older children and adults
Hyperphagia
Obesity
Hypotonia
Hypogonadism
Infertility
Flexibility
Borderline/mild LD
Physical features of Prader-Willi syndrome
Small hands and feet
Hypogonadism
Almond shaped eyes
Thin upper lip
Downturned mouth
Striae
Chromosome affected in Angelman syndrome
15
Parental chromosome responsible for Angelman syndrome
Maternal
LD seen in Angelman syndrome
Severe/profound
Facial features of Angelman syndrome
Fair hair
Blue eyes
Microcephaly
Prevalence of Angelman syndrome
1 in 20000 to 1 in 30000
Percentage of people with Angelman syndrome with epilepsy
90%
Chromosome affected in Williams Syndrome
7
Incidence of Williams Syndrome
1 in 7500 to 1 in 20000 live births
Electrolyte abnormality in Williams Syndrome
Hypercalcaemia
LD seen in Williams Syndrome
Mild to moderate
Medical problems associated with Williams syndrome
Renal abnormalities
Supravalvular aortic stenosis
Thyroid abnormalities
Hypercalcaemia
Physical features of Williams syndrome
Short stature
Elfin like face
Broad forehead
Premature wrinkling
Behavioural features of Williams syndrome
Anxiety, fearfulness and difficulty making friends OR
Outgoing and excessively friendly
Verbal skills comparatively good
Chromosome affected in Cri du chat syndrome
5
Incidence of Cri du chat syndrome
1 in 15000 to 1 in 50000 live births
Physical features of Cri du chat syndrome
Microcephaly
Round face
Epicanthic folds
Broad flat nose
Slanting palpebral fissures
Low set ears
LD seen in Cri du chat syndrome
Severe to profound
Chromosome affected in Smith-Magenis syndrome
17
Incidence of Smith-Magenis syndrome
1 in 25000 live births
Physical features of Smith-Magenis syndrome
Flattened mid face
Short hands and feet
Single palmar crease
High arched palate
Small toes
Protruding tongue
Chromosome affected in DiGeorge syndrome
22
Prevalence of DiGeorge syndrome
1 in 4000
LD seen in DiGeorge syndrome
Mild to moderate in >50%
Facial features of DiGeorge syndrome
Microcephaly
Cleft palate
Small mouth
Long face
Electrolyte abnormality seen in DiGeorge syndrome
Hypocalcaemia
Percentage of people with tuberous sclerosis who have seizures
90%
LD seen in tuberous sclerosis
Absent to profound
Clinical features of tuberous sclerosis
Hamartomas of the CNS
Ash leaf spots
Nail fibromas
Chromosomes affected in tuberous sclerosis
9
16
Chromosome affected in neurofibromatosis
17
Tumours seen in NF I
Benign neurofibromas in the CNS
Tumours seen in NF II
Acoustic neuromas leading to hearing loss
Clinical features of NF
Cafe au lait spots
Neurofibromas
Axillary freckling
Lisch nodules
Psychiatric features of NF
Speech and language difficulties
Moderate to profound LD in 10%
Distractibility
Hyperactivity
Anxiety
Enzyme which is defective in PKU
Phenylalanine hydroxylase
Characteristic features of untreated PKU
Microcephaly
Hypopigmentation of the skin
Language delay
Severe LD
Hyperactivity
Self injuring behaviour
Musty odour of the skin
Features of Laurence-Moon-Biedl syndrome
Retinitis pigmentosa
Polydactyly
Night blindness
Hypogonadism
Mild to moderate LD
Diabetes
Renal issues
Substance build up seen in Lesch-Nyhan syndrome
Uric acid
Sex most affected by Lesch-Nyhan syndrome
Male
Features of Lesch-Nyhan syndrome
Hypotonia
Extra-pyramidal features at 9 months
Hyperreflexia and clonus at 1 year
Seizures
Uncontrollable self injury
Kidney failure
Incidence of congenital hypothyroidism
1 in 4000 live births
Clinical features of congenital hypothyroidism
Puffy face
Large tongue
Dry hair
Constipation
Low muscle tone
Jaundice
LD if untreated
Percentage of LD in males accounted for by Fragile X syndrome
10-12%
Characteristic findings on brain imaging of someone with Fragile X syndrome
Enlarged ventricles
Enlarged hippocampus
Enlarged caudate nuclei
Reduced posterior cerebellar vermis
Age of onset of Lennox Gastaut syndrome
3-5
Triad of features seen in Lennox Gastaut syndrome
Multiple drug resistant seizure types
EEG of slow wave spikes
LD
Sleep pattern seen in Rett syndrome
Excessive somnolence
Most common aetiological cause of LD
Defects in embryogenesis
Rate of autism in a child with an affected sibling
1-10%
Syndrome associated with compulsive self mutilation
Lesch-Nyhan
Inheritance manner of tuberous sclerosis
Autosomal dominant
Percentage of people with ASD who are also obese
20%
Mode of inheritance of Fragile X syndrome
X linked dominant
Heritability of autism
80-90%
Mode of inheritance of Hunter syndrome
X linked recessive
Most common cause of death in people with Down’s syndrome
Infections
Sex most affected by Rett syndrome
Female
Pattern of inheritance of PKU
Autosomal recessive
Syndrome associated with stereotyped, hand wringing movements
Rett syndrome
Syndrome associated with attraction to water
Angelman syndrome
Syndrome associated with intolerance to noise
Rubinstein Taybi syndrome
Syndrome caused by mutations in a gene coding for the enzyme responsible for purine synthesis
Lesch-Nyhan
Condition associated with night blindness, central obesity, and polydactyly
Laurence-Moon-Biedl
Percentage of cases of LD caused by genetic inheritance
5%
Percentage of cases of LD caused by pregnancy related and perinatal problems
10%
Percentage of cases of LD caused by acquired general medical conditions
5%
Percentage of cases of LD caused by environmental influences
15-20%
Percentage of cases of LD with no definite aetiology
30-40%
Percentage of people with Down’s syndrome who have epilepsy
5-10%
Percentage of people with Fragile X syndrome who have epilepsy
20-25%
Percentage of people with Rett syndrome who have epilepsy
90%
Percentage of people with Angelman syndrome who have epilepsy
90%
Percentage of people with tuberous sclerosis who have epilepsy
90%
Mode of inheritance of Lesch-Nyhan syndrome
X linked recessive
Gene associated with Rett syndrome
MECP2
Gene associated with Fragile X syndrome
FMR1
Clinical features of homocystinurea
Mild LD
Marfanoid stature
Visual problems and lens dislocation
Chest deformities
Clinical features of Sanfilippo disease
Dwarfism
Claw hand
Increased body hair
Severe LD
Joint stiffness
Hepatosplenomegaly
Neuroimaging findings in fragile X syndrome
Reduction of the cerebellar vermis
Enlargement of the fourth ventricle
Neuroimaging findings in Down syndrome
Reduced total brain volume
Reduced grey matter volume
Reduced hippocampus and amygdala size
Generalised atrophy for age