Genetics Flashcards

1
Q

What is the role of paediatric genetics?

A
  • Diagnosis in congenital malformations and learning disability
  • Approach to dysmorphic child
  • Investigation into developmental delay
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2
Q

What conditions is Down syndrome associated with?

what chromosome asc with?

A
  • Learning disability
  • Congenital heart disease
  • Hypothyroidism
  • Immunity
  • Early onset Alzheimer disease

Trisomy 21

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3
Q

What ethical issues are there surrounding testing for Down syndrome?

A
  • Regarded as standard care in Western world
  • Non-invasive testing will soon be available
  • Is a world without Down syndrome acceptable?
  • Screening leads to termination
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4
Q

What does congenital mean?

A
  • Present at birth

- Can be genetic, environmental or both

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5
Q

What are the causes of multiple congenital anomaly syndromes?

A
  • 55% unknown
  • 30% single gene disorders
  • 10% chromosomal
  • 5% teratogens
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6
Q

What is the epidemiology of congenital anomalies/

A
  • 3% all births
  • 20% children’s hospital admissions
  • 30% infant deaths
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7
Q

Syndrome

A

A distinct group of symptoms and signs which associated together for a characteristic clinicl picture or entitiy

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8
Q

How common are multiple congenital anomalies?

A
  • Individually rare

- Common as a group

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9
Q

How do you diagnose a rare intellectual disability or malformation syndrome?

A
  • History
  • Description
  • Recognition of patterns
  • Testing
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10
Q

What testing can be performed in diagnosis of a rare intellectual disability or malformation syndrome?

A
  • Microarray standard
  • Targeted testing
  • Moving to exome and genome
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11
Q

What should be looked at when describing a dysmorphic child?

A
  • Position and shape of facial features
  • Hands
  • Growth of child
  • General features
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12
Q

What should be looked at regarding the head of a dysmorphic child?

A
  • Shape
  • Size: macrocephaly, microcephaly
  • Ear position
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13
Q

What type of ears suggest lack of maturity?

A

Low-set, posteriorly rotated

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14
Q

What should be looked at regarding the eyes in a dysmorphic child?

A

Hypertelorism
-Inner canthal distance ICD and inter-pupillary distance IPD increased

Telecanthus / epicanthic folds
-ICD increased

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15
Q

What hand measurements should be taken when examining a dysmorphic child?

A
  • Finger length
  • Digital abnormalities
  • Palmar creases
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16
Q

Give examples of syndromes which can affect the hands.

A
  • Marfan syndrome

- Down syndrome

17
Q

How are the hands affected in Marfan’s syndrome?

A

Middle finger length divided by the total hand length is >44%

18
Q

How can malformation present?

A

Alone or part of a syndrome

19
Q

Give examples of malformation and the gene responsible

A
  • Polysyndactylty alone (Hox D13 one cause)

- Acrocephalopolysyndatyly (Greig / GLI3)

20
Q

How does acrocephalopolysyndactyly present?

A
  • Tall forehead
  • Polydactyly
  • Syndactyly
21
Q

Sequence

A

One abnormality leads to another and can have multiple causes

22
Q

What is Pierre-Robin sequence?

A

Small chin which leads to cleft palate

23
Q

What are the features of foetal akinesia sequence?

A
  • Reduced foetal movements
  • Reduced breathing
  • Contractures
  • Clefting
  • Lung hypoplasia
24
Q

What are deformation and disruption?

A

Pattern of development normal to start with but becomes abnormal

Deformation: Organ parts are there

Disruption: Parts of organ / body part absent

25
Q

Association

A

2 features or more that occur together more often than expected by chance though the mechanism is unclear

26
Q

Give an examples of association.

A

VATER association

  • Vertebral anomalies
  • Ano-rectal atresia
  • Tracheo-oesphageal fistula
  • Radial anomalies
27
Q

What is the genetics behind Turner syndrome?

A

45, X

28
Q

How does Turner syndrome present?

A
  • Lymphoedema (Puffy feet, nuchal translucency / cystic hygroma)
  • Increased carrying angle, low hairline, wide spaced nipples, sandal gap
  • Short stature, occ. v mild learning difficulties
  • Coarctation of aorta, hypothyroidism, UTI, osteoporosis & hypertension
  • Primary amenorrhoea & infertility
29
Q

How can some features of Turner syndrome be mitigated?

A

Hormone therapy

30
Q

How is learning disability investigated genetically?

A
  • Microarray
  • Fragile X
  • Targeted tests driven by phenotype
31
Q

What are the features of 22q11 deletion syndrome?

A
  • Cleft palate
  • Abnormal facies
  • Thymic hypoplasia / immune deficiency
  • Calcium
  • Heart problems
32
Q

What genetic variations are common?

A
  • Copy number variants

- Sequence variation

33
Q

How can we test thousands of genes and find the cause of the disability?

A

Whole-Exome Sequencingof Germline DNA

34
Q

what is a glut1 deficiency?

treatment?

A

SLC2A1 deletion or mutation

Treatment with ketogenic diet

35
Q

why is phenotypic important?

A

The key to assessment of clinical relevance is the phenotype

That’s why accurate description of clinical features is important

A diagnosis helps the family see the future

And can help with future pregnancy planning, clinical care and treatment