Genetics and Dysmorphology Flashcards

1
Q

What are the typical facial features of Down Syndrome?

A

Round face with flat nasal bridge and short neck
Upslanted palpebral fissures
Epicanthic folds
Brushfield spots in iris
Small mouth with protruding tongue
Small ears
Flat occiput and 3rd fontanelle

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2
Q

What are the limb features of Down syndrome?

A

Single palmar creases
Incurved and short 5th fingers
Wide “sandal-toe” gap between 1st and 2nd toes

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3
Q

What are the neurological features of Down syndrome?

A

Hypotonia

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4
Q

What percentage of children with Down syndrome have a congenital heart defect?

A

30-40%

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5
Q

What are the long term or later medical issues in Down syndrome?

A

DD
LD
Short stature
Increased susceptibility to infection
Hearing or visual impairments
Increased risk of hypothyroidism (<15%)
Increased risk of leukaemia and solid tumours (<1%)
Increased risk coeliac disease
OSA
Epilepsy
Early-onset Alzheimers

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5
Q

What types of congenital heart defects are most common with Down syndrome?

A

ASD and AVSD

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5
Q

What are the 3 types of genetic cause for Down syndrome?

A

Meiotic nondisjunction (94%)
Translocation (5%)
Mosaicism (1%)

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6
Q

What are the presenting features of Edwards syndrome?

A

LBW
Prominent occiput
Small mouth and chin
Short sternum
Flexed, overlapping fingers
“rocker-bottom” feet
Cardiac and renal malformations

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6
Q

What gut features can present in Down syndrome?

A

Duodenal atresia
Hirschsprung’s (<1%)

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6
Q

How is Down syndrome diagnosed?

A

Clinical suspicion
rtPCR or FISH

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7
Q

What are the clinical features of Turner syndrome?

A

Lymphoedema of hands and feet in the neonate
Spoon shaped nails
Short stature
Neck webbing or thick neck
Wide carrying angle
Widely spaced nipples
Delayed puberty
Infertility
Hypothyroid risk
Renal anomalies common
Pigmented moles
Recurrent OM
Congenital heart defects

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7
Q

What is trisomy 18 better known as?

A

Edwards syndrome

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7
Q

What is trisomy 13 better known as?

A

Patau syndrome

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7
Q

What are the presenting features of Patau syndrome?

A

Structural defect of the brain
Scalp defects
Small eyes
Cleft lip and palate#
Polydactyly
Cardiac and renal malformations

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7
Q

What is the most common congenital heart defect in Turner syndrome?

A

Coarctation of the aorta

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7
Q

What syndrome is best characterised by the karyotype XO?

A

Turner syndrome

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8
Q

What is the treatment offered in Turner syndrome?

A

Growth hormone
Oestrogen replacement to develop secondary sexual characteristics

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8
Q

How is intellect affected in Turner syndrome?

A

It is often unaffected

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9
Q

Which condition is caused by the 5p microdeletion?

A

Cri-du-Chat syndrome

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10
Q

What are the clinical features of Klinefelter syndrome?

A

Infertility (most common presentation)
Hypogonadism and small testes
Gynaecomastia in adolescence
Tall stature

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10
Q

What are the presenting features in Cri du chat syndrome?

A

High pitched cry in infancy
Hypotonia
Microcephaly
Intellectual disability

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10
Q

What is best described by the karyotype XXY?

A

Klinefelter syndrome

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11
Q

Which condition is caused by the 22q11.2 microdeletion?

A

DiGeorge syndrome

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11
Q

How does Williams syndrome present?

A

Characteristic facies
Transient neonatal hypoglycaemia
Supravalvular aortic stenosis
Mild-mod LD
Short stature

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12
Q

What are the typical features of DiGeorge syndrome?

A

CATCH
Cardiac abnormality (interrupted aortic arch, truncus arteriosus, TOF)
Abnormal facies
Thymic aplasia
Cleft palate
Hypocalcaemia/hypoparathyroidism

Intellectual disability
Autism/ADHD

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13
Q

Which syndrome is caused by a 7q11 microdeletion?

A

Williams syndrome

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14
Q

By which form of inheritance is achondroplasia inherited?

A

AD

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15
Q

By which form of inheritance is familial hypercholesterolaemia (almost always) inherited?

A

AD

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16
Q

By which form of inheritance is Huntington disease inherited?

A

AD

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17
Q

By which form of inheritance is Marfan syndrome inherited?

A

AD

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18
Q

By which form of inheritance is Osteogenesis imperfecta (most forms) inherited?

A

AD

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19
Q

By which form of inheritance is Neurofibromatosis inherited?

A

AD

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20
Q

By which form of inheritance is Noonan syndrome inherited?

A

AD

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21
Q

By which form of inheritance is Tuberous sclerosis inherited?

A

AD

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21
Q

By which form of inheritance is Otosclerosis inherited?

A

AD

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22
Q

By which form of inheritance is Polyposis coli inherited?

A

AD

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23
Q

By which form of inheritance is CAH inherited?

A

AR

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24
Q

By which form of inheritance is achondroplasia inherited?

A

AR

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25
Q

By which form of inheritance is CF inherited?

A

AR

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26
Q

By which form of inheritance is Friedreich Ataxia inherited?

A

AR

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27
Q

By which form of inheritance is Galactosaemia inherited?

A

AR

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28
Q

By which form of inheritance is Glygogen storage diseases inherited?

A

AR

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29
Q

By which form of inheritance is Hurler syndrome inherited?

A

AR

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30
Q

By which form of inheritance is Oculocutaneous albinism inherited?

A

AR

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31
Q

By which form of inheritance is PKU inherited?

A

AR

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32
Q

By which form of inheritance is Sickle cell inherited?

A

AR

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33
Q

By which form of inheritance is Thalassaemia inherited?

A

AR

34
Q

By which form of inheritance is Tay-Sachs disease inherited?

A

AR

35
Q

By which form of inheritance is SMA1 inherited?

A

AR

36
Q

By which form of inheritance is Red-Green colour-blindness inherited?

A

X-linked recessive

37
Q

Which gene is implicated in fragile X syndrome?

A

FMR1 gene

37
Q

By which form of inheritance is Fragile X syndrome inherited?

A

X-linked recessive

37
Q

By which form of inheritance is Haemophilia A and B inherited?

A

X-linked recessive

37
Q

By which form of inheritance is DMD inherited?

A

X-linked recessive

37
Q

By which form of inheritance is G6PD deficiency inherited?

A

X-linked recessive

38
Q

By which form of inheritance is Hunter syndrome inherited?

A

X-linked recessive

38
Q

In an x-linked recessive condition what is the chance that a daughter of a female carrier will carry the condition?

A

1 in 2

38
Q

What abnormalities are considered in VACTERL association?

A

Vertebral anomalies
Anal atresia
Cardiac defects
TracheoEsophageal fistula
Renal anomalies
Limb defects

39
Q

By which form of inheritance is hypophosphataemic rickets inherited?

A

X-linked dominant

39
Q

What conditions involve trinucleotide repeat expansion mutations?

A

Fragile X
Myotonic dystrophy
Huntington’s disease

39
Q

In an x-linked recessive condition what is the chance that a son of a female carrier will have the condition?

A

1 in 2

39
Q

In an x-linked recessive condition what is the chance that a daughter of an affected male will carry the condition?

A

100%

40
Q

Are males or females primarily affected in X-linked dominant conditions?

A

Both, usually males will have a more severe phenotype

40
Q

In an x-linked recessive condition what is the chance that a son of an affected male will have the condition?

A

0

41
Q

What is meant by the imprinting and uniparental disomy phenomenon?

A

Expression of genes dependent on parental sex that transmitted the gene

41
Q

Which condition will occur if a child receives no paternal functional copy of chromosome 15?

A

Prader-Willi Syndrome

41
Q

What are the clinical features of fragile X syndrome?

A

Mod-sev LD
Macrocephaly
Marcoorchidism
Characteristic facies (long face, large everted ears, prominent mandible, broad forehead)
Mitral valve prolapse
Joint laxity
Scoliosis
Autism
Hyperactivity

42
Q

Which condition will occur if a child receives no maternal functional copy of chromosome 15?

A

Angelman syndrome

42
Q

What are the characteristic features of PWS?

A

Characteristic facies
Hypotonia at birth
Hypogonadism
Neonatal feeding difficulties
Faltering growth in infancy
Hyperphagia and obesity inadulthood
DD and LD

43
Q

What are the clinical features of Angelman syndrome?

A

Severe cognitive impairment
Characteristic facial appearance
Ataxia
Epilepsy

44
Q

What are the clinical features of Noonan syndrome?

A

Characteristic facies
Short, webbed neck with trident hair line
Pectus excavatum
CHD (pulmonary stenosis and ASD)
Short stature
Occasional mild LD

44
Q

How are porphyrias inherited?

A

Typically AD but can be AR

45
Q

How is CAH inherited?

A

AR

45
Q

In CAH, when should biological sex be assigned?

A

When karyotype available

46
Q

What chromosomal abnormality is associated with PWS?

A

Deletion of the long arm on paternal chromosome 15 or maternal uniparental disomy

47
Q

How is haemophilia A inherited?

A

X-linked recessive

48
Q

Which gene is associated with achondroplasia?

A

FGFR3 gene

48
Q

Which gene is associated with Rett syndrome?

A

MECP2

49
Q

What are the features of Pallister-Killian syndrome?

A

Bitemporal sparsity of hair
Severe DD
Epilepsy
Hypotonia
Abnormal skin pigmentation

49
Q

What chromosomal abnormality is associated with Pallister-Killian syndrome?

A

Mosaicism for an isochromosome comprising the short arms for Ch12

50
Q

What is the embryological failure than leads to Treacher-Collin’s syndrome?

A

Underdevelopment of first pharyngeal arch

50
Q

How is NF1 typically inherited?

A

AD

50
Q

What are the features of Treacher-Collins syndrome?

A

Underdeveloped facial bones
Micrognathia
Downward-slanting eyes

51
Q

What is the typical inheritance pattern in Kearns-Sayre syndrome?

A

Sporadic cases

52
Q

What are the typical symptoms associated with Kearns-Sayre syndrome?

A

Pigmentary retinopathy
Progressive external ophthalmoplegia
Heart block
Ataxia +/- elevated CSF protein

52
Q

What is formed as the penultimate step before haem formation?

A

Protoporphyrin

53
Q

What ophthalmological features are seen in tuberous sclerosis?

A

Harmatomas or retinal hypopigmented patches

54
Q

How does Bardet-Biedl syndrome present?

A

Obesity
Hypogonadism
Retinal degeneration
Polydactyly
Cardiac defects
Renal anomalies
T2DM
Anosmia

55
Q

How is Bardet-Biedl syndrome inherited?

A

AR

56
Q

What are the features of branchio-oto-renal syndrome?

A

Ear pits
Hearing loss
Renal abnormalities (dysplastic kidneys or aplasia)

57
Q

What is the inheritance of branchio-oto-renal syndrome?

A

AD - variable penetrance

58
Q

What chromosome is involved in branchio-oto-renal syndrome?

A

Chromosome 8 (most commonly)

59
Q

What chromosomal abnormality is associated with Cr-du-chat syndrome?

A

5p deletion

60
Q

What are the typical features of Lesch-Nyhan syndrome?

A

Overproduction of uric acid - gout and kidney stones
Neurological dysfunction
Self-mutilating behaviours - such as lip and finger biting

61
Q

How does Fanconi anaemia present?

A

Radial ray abnormalities (e.g. absent thumbs)
SGA
Pancytopenia

62
Q

How is Fanconi anaemia diagnosed?

A

Chromosome breakage studies

63
Q

How is Fanconi anaemia inherited?

A

AR

64
Q

How is Cowden disease inherited?

A

AD

64
Q

How does FISH work?

A

Fluorescent dye is attached to chromosomal probes, which then attach to the target DNA to locate each section of the chromosomes

64
Q

What are the features of Simpson-Golabi-Behmel syndrome in males?

A

Macrocephaly
Coarse facial features
Down-slanting palpebral fissures
DD

65
Q

What are the features of Cowden disease?

A

Multiple hamartomas
Increased risk malignancies incl. thyroid and endometrial
Macrocephaly
Developmental delay

65
Q

What are the features of mosaic trisomy 8?

A

Deep-set eyes
Everted lower lip
Deep palmar and plantar creases
Micrognathia
Elongated skull
Upturned nose

66
Q

What is the inheritance pattern of Simpson-Golabi-Behmel syndrome?

A

X-linked recessive

66
Q

How is Jeune syndrome inherited?

A

AR

66
Q

What are the features of Simpson-Golabi-Behmel syndrome in females?

A

Subtle facial manifestations - large mouth and pointed chin
Sometimes a coccygeal appendage

67
Q

How does Jeune syndrome present?

A

Lung hypoplasia
Poor cartilage development
Short thorax and small ribs and limbs
Renal abnormalities - cystic kidneys

67
Q

What mutated gene causes Simpson-Golabi-Behmel syndrome?

A

GPC3 gene

67
Q

What is Southern blotting technique?

A

Demonstration of the presence or absence of specific DNA fragments in a mixture of DNA

67
Q

What is the unstable trinucleotide repeat in fragile X syndrome?

A

CGG

68
Q

In what condition are brushfield spots commonly seen?

A

T21

69
Q

What are the features of Beckwith-Wiedemann syndrome?

A

Large tongue
Hepatomegaly
LGA
Umbilical hernia
Macroglossia
Macrosomia
Hemi-hyperplasia
Organomegaly
Cleft palate

70
Q

What are the features of Angelman syndrome?

A

DD
Lack of speech
Walking and balance disorders
Happy demeanor
Jerky movements

71
Q

What are the features of Pendred syndrome?

A

Severe, profound bilateral SN deafness
Vestibular dysfunction
Goitre
Bilateral dilated vestibular aqueducts

72
Q

How is Pendred inherited?

A

AR

73
Q

What are the features of Sotos syndrome?

A

Macrocephaly
Prominent forehead
Down-slanting palpebral fissures
Prominent jaw
High and narrow palate
Can be assoc. with ventricular dilatation and seizures

74
Q

What genetic mutation causes Sotos syndrome?

A

NSD1 gene mutations or deletions affecting 5q35 locus
Most are de novo

75
Q

How does Tay-Sachs present?

A

Cherry red spot on ophthalmological exam
Affects central and peripheral nervous system