Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MCRP: Clinical Sciences > Genetic Disorders > Flashcards

Genetic Disorders Flashcards

(69 cards)

Start Studying
1
Q

What inheritance is achondroplasia?

A

Autosomal dominant

70% are de novo mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the mutation in achondroplasia?

A

FGFR-3 - fibroblast growth factor 3
Chromosome 4
Results in abnormal collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Phenotype of achondroplasia?

A

Short limbs (rhizomelia) with shortened Fingers (brachydactyly)
Large head with frontal bossing and Narrow foramen magnum
Midface hypoplasia with a flattened Nasal bridge
‘trident’ hands
lumbar lordosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is alkaptonuria?

A

rare autosomal recessive disorder of phenylalanine and tyrosine metabolism

lack of the enzyme homogentisic dioxygenase (HGD) which results in a build-up of toxic homogentisic acid

Kidneys filter homogentisic acid –> black urine

However accumulates in other tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the inheritance of alkaptonuria?

A

Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the features of alkaptonuria?

A

Pigmented sclera
Urine turns black if left exposed to the air
Intervertebral disc calcification may Result in back pain
Renal stones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Treatment of alkaptonuria?

A

High-dose vitamin C
Dietary restriction of phenylalanine and tyrosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

General what type of disorders are autosomal dominant and autosomal recessive?

A

Recessive: Metabolic
Dominant: Structural

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What autosomal dominant conditions are exceptions to the general rule?

A

Dominant is normally structural

These metabolic conditions are exceptions:
some ‘metabolic’ conditions such as Hunter’s and G6PD are X-linked recessive
Hyperlipidemia type II and hypokalemic periodic paralysis are autosomal dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What autosomal recessive conditions are exceptions to the general rule?

A

Recessive normally metabolic

These sttuructal conditions are exception:
Ataxia telengectasis
Fredricks’ ataxia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the features of patau syndrome?

A

Microcephalic, small eyes
Cleft lip/palate
Polydactyly
Scalp lesions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the chromosomal abnormality in patau syndrome?

A

Trisomy 13

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the features of Edward’s syndrome?

A

Micrognathia (undersized jaw)
Low-set ears
Rocker bottom feet
Overlapping of fingers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the chromosomal abnormality in Edward’s syndrome?

A

Trisomy 18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the features of fragile X syndrome?

A

Learning difficulties
Macrocephaly
Long face
Large ears
Macro-orchidism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the features of Noonan syndrome?

A

Webbed neck
Pectus excavatum
Short stature
Pulmonary stenosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the features of Pierre robin syndrome?

A

Micrognathia (undersized jaw)
Posterior displacement of the tongue (may result in upper airway obstruction)
Cleft palate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the features of prayer-willi syndrome?

A

Hypotonia
Hypogonadism
Obesity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the features of William’s syndrome?

A

Short stature
Learning difficulties
Friendly, extrovert personality
Transient neonatal hypercalcaemia
Supravalvular aortic stenosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the features of criteria du chat?

A

Characteristic cry (hence the name) due to larynx and neurological problems
Feeding difficulties and poor weight gain
Learning difficulties
Microcephaly and micrognathism
Hypertelorism (large distance between eyes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the genetic mutation in DiGeorge syndrome?
What is the inheritance pattern?

A

deletion of a section of chromosome 22
22q11.2 deletion

Autosomal dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the features of DiGeorge Syndrome?

A

C - Cardiac abnormalities
A - Abnormal facies
T - Thymic aplasia
C - Cleft palate
H - Hypocalcaemia/ hypoparathyroidism
22 - Caused by chromosome 22 deletion

T-lymphocyte deficiency/dysfunction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the features of Down syndrome?

A

Face: upslanting palpebral fissures, epicanthic folds, Brushfield spots in iris, protruding tongue, small low-set ears, round/flat face
Flat occiput
Single palmar crease, pronounced ‘sandal gap’ between big and first toe
Hypotonia
Congenital heart defects (40-50%, see below)
Duodenal atresia
Hirschsprung’s disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the cardiac complications in Down syndrome?

A

Endocardial cushion defect (most common, 40%, also known as atrioventricular septal canal defects)

Ventricular septal defect (c. 30%)

Secundum atrial septal defect (c. 10%)
tetralogy of Fallot (c. 5%)

Isolated patent ductus arteriosus (c. 5%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are adult complications of Down syndrome?
Subfertility Learning difficulties Short stature Repeated respiratory infections (+hearing impairment from glue ear) Acute lymphoblastic leukaemia Hypothyroidism Alzheimer's disease Atlantoaxial instability
26
What is the genetic disorder and inheritance in fabry's disease?
X-linked recessive deficiency of alpha-galactosidase A
27
What are the features of fabry's disease?
burning pain/paraesthesia in childhood angiokeratomas lens opacities proteinuria early cardiovascular disease
28
What are the features of fragile X syndrome?
learning difficulties large low set ears, long thin face, high arched palate macroorchidism hypotonia autism is more common mitral valve prolapse
29
What is the genetic mutation in fragile X syndrome?
Trinucleotide repeat disorder Features in females (who have one fragile chromosome and one normal X chromosome) range from normal to mild
30
How should fragile X be investigated?
Analysis of the number of CGG repeats using restriction endonuclease digestion and Southern blot analysis
31
What are the features of homocystinuria ?
often patients have fine, fair hair Marfanoid body habitus: arachnodactyly etc osteoporosis kyphosis neurological: may have learning difficulties, seizures ocular downwards (inferonasal) dislocation of lens severe myopia increased risk of arterial and venous thromboembolism also malar flush, livedo reticularis
32
What the mutation in homocystinuria and its inheritance?
Autosomal recessive disease caused by a deficiency of cystathionine beta synthase. This results in severe elevations in plasma and urine homocysteine concentrations.
33
What is the test for homocystinuria?
Increased homocysteine levels in serum and urine Cyanide-nitroprusside test: also positive in cystinuria
34
What is the treatment of homocystinuria ?
Vitamin B6 (pyridoxine) supplements.
35
What is Mccune Albright syndrome?
Precocious puberty Cafe-au-lait spots polyostotic fibrous dysplasia (fibrous dysplasia of bone) short stature
36
How is Mccune Albright syndrome inherited?
Somatic mutation in the GNAS gene.
37
By what mechanism does mitochondrial disease pass on ?
inheritance is only via the maternal line all of the children of an affected female will inherit the disease generally, encode rare neurological diseases poor genotype:phenotype correlation - within a tissue or cell there can be different mitochondrial populations - this is known as heteroplasmy
38
How are mitochondrial disorders investigated?
Muscle biopsy classically shows 'red, ragged fibres' due to increased number of mitochondria
39
What is MELAS?
MELAS syndrome: mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes Mitochondrial disorder
40
What is MERRF?
MERRF syndrome: myoclonus epilepsy with ragged-red fibres Mitochondrial disorder
41
What is Kearns-Sayre syndrome?
Kearns-Sayre syndrome: onset in patients < 20 years old, external ophthalmoplegia, retinitis pigmentosa. Ptosis may be seen
42
What are the features of Noonan syndrome?
cardiac: pulmonary valve stenosis ptosis triangular-shaped face low-set ears coagulation problems: factor XI deficiency As well as features similar to Turner's syndrome (webbed neck, widely-spaced nipples, short stature, pectus carinatum and excavatum),
43
What is the inheritance of Noonan syndrome?
autosomal dominant
44
What are features of fredreick's ataxia?
Presents 5-15 Dysarthria, and ataxia (broad-based gait) Areflexic Echocardiographic findings of hypertrophic cardiomyopathy Inheritance: autosomal recessive
45
What is the genetic features of pheynlkeonuria?
defect in phenylalanine hydroxylase, an enzyme which converts phenylalanine to tyrosine. High levels of phenylalanine lead to problems such as learning difficulties and seizures. gene for phenylalanine hydroxylase is located on chromosome 12.
46
What are the features of PKU?
usually presents by 6 months e.g. with developmental delay child classically has fair hair and blue eyes learning difficulties seizures, typically infantile spasms eczema 'musty' odour to urine and sweat*
47
How is PKU diagnosed?
Guthrie test: the 'heel-prick' test done at 5-9 days of life - also looks for other biochemical disorders such as hypothyroidism hyperphenylalaninaemia phenylpyruvic acid in urine
48
What is the molecular mechanism behind prader-willi syndrome?
phenotype depends on whether the deletion occurs on a gene inherited from the mother or father: Prader-Willi syndrome if gene deleted from father Angelman syndrome if gene deleted from mother Absence of the active Prader-Willi gene on the long arm of chromosome 15. This may be due to: microdeletion of paternal 15q11-13 (70% of cases) maternal uniparental disomy of chromosome 15
49
What is the phenotype of prader-willi syndrome?
hypotonia during infancy dysmorphic features short stature hypogonadism and infertility learning difficulties childhood obesity behavioural problems in adolescence
50
What is the tumour suppressor mutation in lifraumani?
p53
51
What is the tumour suppressor mutation in colorectal cancer?
APC
52
Tumour suppressor in wilm's tumour?
WT1
53
tumour suppressor in retinoblastoma?
RB1
54
Tumour suppressor in melanoma?
p16 MTS-1
55
Features of turner's syndrome?
short stature shield chest, widely spaced nipples webbed neck bicuspid aortic valve (15%), coarctation of the aorta (5-10%) primary amenorrhoea cystic hygroma (often diagnosed prenatally) high-arched palate short fourth metacarpal multiple pigmented naevi lymphoedema in neonates (especially feet) gonadotrophin levels will be elevated hypothyroidism is much more common in Turner's horseshoe kidney: the most common renal abnormality in Turner's syndrome
56
What additionally are Turner syndrome patients at risk of?
Autoimmune disease (especially autoimmune thyroiditis) and Crohn's disease X linked genetic disorders e.g. haemophilia
57
Examples of X linked dominant conditions?
Alport's syndrome (in around 85% of cases - 10-15% of cases are inherited in an autosomal recessive fashion with rare autosomal dominant variants existing) Rett syndrome Vitamin D resistant rickets
58
Who is affected in an X linked recessive condition?
Males only Or Turner women
59
Examples of X linked recessive conditions?
Androgen insensitivity syndrome Becker muscular dystrophy Colour blindness Duchenne muscular dystrophy Fabry's disease G6PD deficiency Haemophilia A,B Hunter's disease Lesch-Nyhan syndrome Nephrogenic diabetes insipidus Ocular albinism Retinitis pigmentosa Wiskott-Aldrich syndrome Chronic granulomatous disease (in > 70%)
60
Autosomal exceptions?
Autosomal recessive conditions are 'metabolic' - exceptions: inherited ataxias Autosomal dominant conditions are 'structural' - exceptions: Gilbert's, hyperlipidaemia type II
61
How to differentiate between Marfarns and Homocystinuria?
Marfarns: Upward lens dislocation Homo: Downward lens dislocation
62
What Infections are digeorge patients at risk from?
Cryptococcus
63
Examples of X linked recessive conditions?
A - androgen insensitivity syndrome B - Becker/Duchenne C - colour blindness D - Diabetes insipidus (nephrogenic) E - eyes (retinitis pigmentosa) F - Fabry G - G6PD deficiency H - haemophilia A/B, Hunter's
64
What are the features of Barter's syndrome?
Metabolic alkalosis + hypokalaemia usually presents in childhood, e.g. Failure to thrive polyuria, polydipsia hypokalaemia normotension weakness Autosomal recessive Loop diuretics work by inhibiting NKCC2 - think of Bartter's syndrome as like taking large doses of furosemide
65
What is the mechanism of Barter's syndrome?
defective chloride absorption at the Na+ K+ 2Cl- cotransporter (NKCC2) in the ascending loop of Henle.
66
What cardiovascular problems are seen in digeorge?
Truncus arteriosus and tetralogy of Fallot
67
Hyperlipidaemia type II inheritance?
Autosomal dominant
68
Hyperkalaemic periodic paralysis?
Autosomal dominant
69
Fragile X syndrome genetics?
Trinucleotide repeat disorder FMR1 gene on X chromosome

MCRP: Clinical Sciences (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions