Learning Disability 1.2 Flashcards
Incidence of Fragile X
1/3000
Most common inherited cause of LD
Fragile X
IQ of most people with Fragile X
<50
How many men with LD have Fragile X?
10-12%
How many children with Fragile X have autism?
50%
Genetics of Fragile X?
Trinucleotide triplet repeat - CGG - on long arm of chromosome X
Which chromosome has the trinucleotide repeat in Fragile X?
Xq27.3-FMR1
What is FMR1 gene needed for?
Normal neural development
Penetrance of Fragile X
Low
Why is Fragile X more common in males?
Protective effects of second normal X chromosome in females
Clinical features of Fragile X
Large head & ears Long, narrow face Short Post pubertal macro-orchidism Hyperextensible joints Seizures
How many people with Fragile X have seizures?
20-25%
Which people with Fragile X have mild LD?
Women
Behavioural features of Fragile X
Hyperactivity Inattention Stereotypies Speech & language delays Repetitive mannerisms Shyness Gaze avoidance Communication difficulties
Brain imaging in Fragile X
Enlarged ventricles, hippocampus & caudate nuclei
Reduced posterior cerebellar vermis
What is higher triplets in Fragile X associated with?
Lesser IQ
When is reduced IQ most pronounced in Fragile X?
Ages 8-12
What is drop in IQ in Fragile X related to?
Higher stress upon abstract difficulties in different IQ tests used in adults vs children
Genetics of Turner X
Chromosomal aberration of part or all of X chromosome (45,X)
Prevalence of Turner X
1/2000
1/5000 females at birth
How many Turner-syndrome conceptions end in spontaneous abortion or still birth?
99%
Clinical features of Turner X?
Short Low hairline Low-set ears Broad chest Widely spaced nipples Webbed neck Obesity
Puberty in Turner X?
Ovarian failure before birth
Puberty does not occur naturally
Behavioural features of Turner X?
Hyperactivity and distractibility in childhood
Poor social skills & low self-esteem in adolescence
LD in Turner X?
Not typically
IQ in Turner X?
Normal intelligence
How many people with Turner X have VSD or coarctation of aorta?
12%
What is Triple X syndrome also known as?
Trisomy X
XXX
Genetics of Trisomy X
Presence of extra C chromosome in each cell of human female
Incidence of Triple X
1:1000 female births
How many people with Triple X have mild LD?
60-70%
Features of Triple X
Delayed language development
Motor coordination problems
Accelerated growth until puberty
Premature Ovarian failure
What psychiatric problems is Triple X associated with?
Anxiety
Increased incidence of schizophrenia
Other names for Klinefelters?
47,XXY
XXY
Incidence of Klinefelts
1:500 - 1:1000 live male births
Primary feature of Klinefelters
Sterility
Features of Klinefelters
Sparse body hair
Hypogonadism
Gynaecomastia
When does diagnosis of Klinefelters typically occur?
Puberty with variable degree of sexual characteristics
Height of those with Klinefelters?
Taller than average by 4cm
Thin build
Median IQ of Klinefelters
90
most in 60-70
Behavioural features of Klinefelters
Less introvertive & assertive
Less social
Poorer school performance
In which academic areas do Klinefelters do poorly?
Reading
Spelling
Genetics of XYY
Human male has extra Y chromosome
Another name of XYY
47, XYY
Incidence of XYY
1:1000 male births
IQ of XYY
Lower than average
Behavioural features of XYY
Associated with behavioural problems
Name some sex chromosome disorders
Fragile X
Turners
Klinefelters
XYY
Name some autosomal deletion and duplication disorders
Prader-Willi Angelmann Williams Cri-du-chat Smith-Magenis DiGeorge Rubinstein-Taybi
Genetics of Prader-Willi
Deletion or inexpression of 7 genes on chromosome 15q11-13 on paternal chromosome
M:F incidence of Prader-Willi
4:3
Incidence of Prader-Willi
1/10,000-1/25,000 live births
Early features of Prader-Willi
Hypotonia Lethargy Hypogonadism Breech/Caesarian Failure to thrive Excessive sleepiness Triangular mouth can cause feeding and swallowing problems
Childhood features of Prader-Willi
Increase in over-eating
Insatiable appetite can lead to stealing food
Sometimes consumption of unpalatable food
How many people with Prader-Willi have hyperphagia?
80%
Features of Prader-Willi in adulthood?
Obesity Hypotonia Infertility Hypogonadism Sparse pubic hair Extreme flexibility
IQ of Prader-Willi
<70 in 90%
Physical features of Prader-Willi
Prominent nasal bridge and forehead Small hands and feet Almond-shaped eyes Flattened face Thin upper lip Downturned mouth Lack of complete sexual development Striae Delayed motor development
How many people with Prader-Willi have autistic features
15%
Life expectancy of Prader-Willi
Dependent on obesity and associated physical health problems
Genetics of Angelmann
Deletion in 15q12 of maternal origin
How many people with Angelman have a deletion in maternally derived chromosome 15
80%
Prevalence of Angelman
1/20,000-1/30,000
Clinical features of Angelman
Happy disposition Paroxysmal laughter Hand flapping Clapping Ataxia
LD in Angelman
Severe/profound
Facial features of Angelman
Fair hair and blue eyes Microcephaly Flattened occiput Long face Prominent jaw Wide mouth Widely-spaced teeth Thin upper lip Pointed chin
How many people with Angelman have fair hair and blue eyes?
66%
How many people with Angelman have epilepsy?
90%
EEG changes in Angelman
Characteristic with changes noted as early as age 3
Genetic cause of Williams
Deletion of around 25 genes from long arm of chromosome 7
Prevalence of Williams
1/7500-20,000
Characteristic feature of Williams?
Elfin-like facial appearance
Infants with Williams?
Irritable Feeding problems Failure to thrive Developmental delay Growth retardation
How many children with Williams have high serum calcium levels?
> 60%
IQ in Williams?
40-80
Average 56
Features of Williams
Short, growth retardation
Premature wrinkling and sagging of skin
Hoarse voice
What physical problems are associated with Williams?
Renal and thyroid
Supravalvular aortic stenosis
Hypercalcaemia
Behavioural features of Williams?
Anxious, fearful Hypersensitive or outgoing Sociable Disinhibited Excessively friendly
What skills are often better in Williams?
Verbal better than motor or visuospatial
Genetics of Cri-du-chat
Partial deletion at 5p15.2
How many deletions in Cri-du-chat are spontaneous?
85%
Origin of majority of Cri-du-chat deletions?
Paternal
Incidence of Cri-du-chat
1/15,000-1/50,000
M:F ratio of Cri-du-chat
4:3
Characteristic feature of Cri-du-chat
Infant has high-pitched cry that resembles a cat
Characteristics of Cri-du-chat
Pronounced microcephaly Round face with hypertelorism Epicanthal folds Slanting palpebral fissues Broad flat nose Low-set ears Micrognathia Dental malocclusion
LD in Cri-du-chat?
Severe-profound
Behavioural features of Cri-du-chat
Hyperactivity in children
Stereotypies
Self-injury
Tantrums
Physical diseases associated with Cri-du-chat
Respiratory & ear infections
Congenital heart disease
GI abnormalities
Incidence of Smith-Magenis
1:25,000
Genetics of Smith-Magenis
Complete or partial deletion of 17p11.2
LD in Smith-Magenis
> 75% have mild-moderate LD
Features of Smith-Magenis
Flattened mid face Abnormally shaped upper lip Short hands and feet Single transverse crease Abnormally placed ears Protruding tongue High arched palate Small toes Hoarse, deep voice
Behavioural features of Smith-Magenis
Severe self-injury
Sleep disturbance (decreased REM)
Behavioural problems
Reduced sensitivity to pain and heart
What is severity of cognitive impairment correlated with in Smith-Magenis?
Size of 17p11 deletion
Genetics of DiGeorge
Microdeletion of 11q11.2
How many incidence of DiGeorge arise denovo?
90%
How many people with DiGeorge have an affected parent?
10%
Prevalence of DiGeorge
1/4000
LD of DiGeorge
Mild/moderate
Physical abnormalities associated with DiGeorge
Teratology of Fallot VSD Interrupted aortic arch Pulmonary atresia Hypocalcaemia - 60% Small optic discs Tortuous retinal vessels Cataracts Hearing problems Renal problems Inguinal/umbilical hernias Hypospadias - 10% of males
Facial features of DiGeorge
Microcephaly Cleft palate Small mouth Long face Prominent tubular nose Hypoplasia of adenoids Nasal speech Bulbous nasal tip Narrow palpebral fissue Minor ear abnormalities
Other features of DiGeorge
Seizures Short stature Long, thin hands Hypotonia Hyperextensible fingers
Behavioural problems in DiGeorge
Difficulties with reciprocal social interaction
Blunted/inappropriate affect
Psychiatric problems associated with DiGeorge
Schizophrenia-like psychosis
M:F ratio of Rubinstein-Taybi
1:1
Incidence of Rubinstein-Taybi
1/125,000-300,000 births
Genetics of Rubinstein-Taybi
Microdeletions in some cases at 16p13.3
Features of Rubinstein-Taybi
Short
Broad thumbs and first toes
Feeding difficulties in infants
Seizures
LD in Rubinstein-Taybi
Moderate-severe
Facial features of Rubinstein-Taybi
Microcephaly Prominent nose Broad nasal bridge Hypertelorism Protsis
Physical problems in Rubinstein-Taybi
Congenital heart disease
EEG abnormalities
IQ of Rubinstein-Taybi
Performance IQ>verbal IQ
Behavioural features of Rubinstein-Taybi
Inattentive Distractible Expressive language difficulties Friendly disposition Propensity for self-stimulatory activities Intolerant of loud noises
Name some autosomal dominant conditinos
Tuberous sclerosis complex 1 and 2 (TS 1+2)
Neurofibromatosis Type 1 (NF1)
Sturge-Weber
M:F ratio of TS 1 +2
1:1
Clinical features of TS 1+2
Seizures - 90%
LD of TS 1+2
All degrees
30% have no LD
First common feature of TS 1+2
‘Salaam attacks’ (infantile spasms)
Physical features of TS 1+2
Hamartomas of CNS
Ash leaf spots
Fibromas of nails
Tumours in heart muscle & kidneys
What are Ash leaf spots?
Depigmented skin patches
Behavioural features of TS 1+2
Autism Hyperactivity Impulsivity Aggression Self-injury Sleep disturbances
M:1 of NF1
1:1
Genetics of NF1
Mutation of a gene on chromosome 17 which is responsible for control of all cell division
Physical problems associated with NF1
Tumours along CNS
IQ of NF1
50% have associated speech and language difficulties
Verbal IQ>performance IQ
LD in NF1
10% have moderate-profound LF
Behavioural features of NF1
Distractible
Impulsive
Hyperactive
Anxious
Psychiatric associations with NF1
Anxiety and mood disorders
Diagnosis of NF1 as per National Institute of Health
6 or more cafe au lait spots
2 or more neurofibromas of any type of 1 plexiform neurofibroma
Freckling in axillary of inguinal regions
Optic glioma
2 or more Lisch nodules
First degree relative with NF1
Distinctive osseous lesions
Criteria for cafe au lait spots
> 5mm diameter pre-pubertal
>15mm post-pubertal
What are Lisch nodules?
Pigmented iris hamartomas
Give examples of distinctive osseous nodules in NF1
Sphenoid dysplasia
Thinning of long bone cortex with or without pseudarthrosis
Clinical features of Sturge-Weber
LD
Epilepsy
Hemiparesis
What physical signs is Sturge-Weber associated with?
Port-wine stains and angiomas of meninges in temporal and occipital areas
Name some Autosomal Recessive disorders
Phenylketonuria (PKU)
Hurler
Sanfillipo
Laurence-Moon-Biedl
Genetic cause of PKU
Deficit in phenylalanine hydroxylase enzyme activity which leads to build up of phenylalanine
Caused by inborn error of impaired metabolism
How many children with PKU develop seizures
25% - generalised
Features of PKU
Microcephaly
Hypopigmentation of skin
Language delay
Musty odour on skin
LD of PKU
Severe
Behavioural features of PKU
Hyperactivity
Self-injury
How is PKU managed
Restricting levels of phenylalanine through diet and medication
What causes Hurler?
Deficiency in enzyme alpha-L iduronidase leading to accumulation of glycosaminoglycans
Features of urler
Short
Developmental delay
Facial features of Hurler
Hirsuitism
Corneal clouding
Coarse facial features
Large tongue
When is developmental delay evident in Hurler?
By end of first year
Stop developing between ages 2-4
Mental decline and loss of physical skills after this
Which physical problem is Hurler associated with?
Hearing problems
Mortality in Hurler
Frequently before the age of 10
Cause of Sanfillipo
Disorder of breakdown of heparan sulphate
Incidence of Sanfillipo
1/70,000 births
LD in Sanfillipo
Severe
Features of Sanfilippo
Claw hand Dwarfism Hypertrichosis Joint stiffness Biconvex lumbar vertebrae
Physical problems associated with Sanfillipo
Hearing loss
Hepatosplenomegaly
Behavioural problems in Sanfillipo
Restlessness
Sleep problems
Challenging behaviour
Prognosis of Sanfillipo
Poor
Most die between ages of 20-30 from respiratory tract infections
Genetics of Laurence-Moon-Biedl syndrome
Associated with multiple loci: 11q13 11q21 15q22 3p13
LD of Laurence-Moon-Biedl
Mild to moderate
Features of Laurence-Moon-Biedl
Retinitis pigementosa Night blindness due to red cone atrophy Polydactyly Spastic paraplegia Hypogonadism NIDDM Renal problems
Name some X-linked recessive conditinos
Lesch-Nyhan
Hunter
Genetics of Lesch-Nyhan
Defect of long arm of X chromosome
Prevalence of Lesch-Nyhan
1/380,000-1/1,000,000
Underlying cause of Lesch-Nyhan
Deficiency of hypoxanthine-quanine phophoribosyltransferase leads to uric acid in body fluids
What does partial deficiency in HGPRT (enzyme involved in Lesch-Nyhan) lead to?
Gout
Gender differences in Lesch-Nyhan?
Mostly male
Early features of Lesch-Nyhan
Hypotonia
Delayed motor milestones
By what stage do neurological signs develop in Lesch-Nyhan?
9 months
What neurological signs develop in Lesch-Nyhan?
Spasticity
Choreo-athetoid movements
Hyperreflexia
Clonus
How many people with Lesch-Nyhan have seizures?
50%
Behavioural problems in Lesch-Nyhan
Uncontrollable self-injury
Physical and verbal aggression
Physical problems in Lesch-Nyhan
Failure of sexual development
Kidney failure
Uric acid deposition
When does self-injury occur in Lesch-Nyhan?
Ages 2-3
Cause of death in Lesch-Nyhan
Kidney failure secondary to uric acid deposition or infection
Incidence of Hunter
1:130,000 live births
Inheritance of Hunter
X-linked recessive
Inheritance of Lesch-Nyhan
X-linked recessive
Cause of Hunter
Deficiency of iduronate sulfatase leading to accummulation of glycosaminoglycans
When do sx of Hunters become noticeable?
After age of 1
Features of Hunter
Coarse face with flat nasal bridge Flared nostrils Ataxia Joint stiffness Growth retardation
Physical features of Hunter
Hearing loss Hernias Hepatosplenomegaly Recurrent respiratory and ear infections Cardiovascular abnormalities
Behavioural features of Hunter
Hyperactivity
Delayed speech with loss of speech at 8-10 years
Restlessness
Sleep abnormalities
LD in Hunters
Not all have LD but those who do have shorter life expectancy by 15 years
Life expectancy in Hunters without LD
20-30
Cause of death in Hunter
Neurodegenaration and physical complications of the disease
Incidence of Cornelia de Lange
1/10,000-30,000
What are majority of Cornelia de Lange cases due to?
Spontaneous gene mutations
What genes are associated with Cornelia de Lange?
Multiple including mutation of NIPBL on chromosome 5
How many cases of Cornelia de Lange are due to mutation of NIPBL on chromosome 5?
50%
LD in Cornelia de Lange?
moderate or Severe
Features of Cornelia de Lange
Low birth weight Small & delayed growth Developmental delay Microcephaly Hypertrichosis Long philtrum Small, upturned nose Downturned lips Low set ears Small hands and feet
Behavioural problems in Cornelia de Lange
Self-stimulation
Aggression
Self-injury
Preference for strict routine
Which physical problems is Cornelia de Lange associated with?
GI - mainly reflux Congenital heart defects Visual & hearing problems Skin problems Epilepsy
At what stage of pregnancy can fetal alcohol syndrome occur from alcohol use?
All 3 trimesters
How many children are affected with Fetal alcohol syndrome?
1/00
How many babies born in the Uk each year have fetal alcohol syndrome?
6000-7000
What is significant alcohol use in pregnancy associated with in the developing fetus?
Cognitive impairment
Features of fetal alcohol syndrome
Microcephaly Short palpebral fissues Flat philtrum Thin upper lip Short stature
Neurocognitive deficits in fetal alcohol syndrome
Impulsivity Hyperactivity Concrete thinking Visuospatial problems Poor judgement Poor impulse control Memory deficits
Incidence of congenital hypothyroidism
1/4000
Gender differences in congenital hypothyroidism
More common in females
Clinical features of congenital hypothyroidism
Puffy face Large, protruding tongue Dry hair Constipation Low muscle tone
Sx of congenital hypothyroidism if left untreated
Jaundice
Failure of cognitive development leading to LD
How many people with epilepsy have LD?
30-40%
Prevalence of epilepsy in LD patients
20-25%
Prevalence of epilepsy in severe LD
30-50%
Prevalence of epilepsy in mild LD
15-20%
Prevalence of epilepsy in Downs
5-10%
When can epilepsy be misdiagnosed in LD?
Sx of sudden, unexplained aggression, self-mutilation and other bizarre behaviours e.g. stereotyped movements,fixed staring, rapid eye blinking, exaggerated startle reflex, attention deficits and unexplained lethargy
Seizures in Fragile X
Infrequent, mild, easily controlled and disappear by adolescence
What are most seizures in Fragile X called?
Benign rolandic epileppsy
How many patients with Retts have epilepsy?
90%
How many patients with Angelman have epilepsy?
90%
In which LD is epilepsy very common?
Retts
Angelman
Late stages of neuronal ceroid lipofuscinoses
Sialidosis Type 1
Tay-achs
Type 3 Gauchers
Mitochondrial encephalopathy with lactic acidosis and strokes
Myoclonic epilepsy with ragged red fibres
In which patients are behavioural problems secondary to antiepileptics common?
Brain injury
LD
Which antiepieptics may cause behavioural problems?
Phenobarbitone
Primidone
Benzos
Vigabatrin
When do infantile spasms typically occur?
4-6 months
In how many children with infantile spasms do they occur in the first year?
90%
Describe infantile spasms
Resemble Moro reflex with sudden, brief flexion of neck and trunk, raising both arm forwards, flexion at elbows and flexion of legs at the hips.
What might be the only feature of infantile spasms at the early stage?
Neck flexion
EEG of infantile spasms
Slow waves of high voltage intermixed with diffuse or asynchronous spikes in both hemispheres or contralateral hemisphere if unilateral
What is the name of the EEG in infantile spasms?
Hypsarrhythmia
What is West syndrome?
Triad of infantile spasm, hypsarrthymias and LD
What is Lennox Gestaut syndrome associated with?
LD
Multiple generalised seizures - tonic, clonic and absence
EEG in Lennox Gestaut syndrome?
Multiple spikes