Genetics Flashcards

1
Q

What is Kleinfelter’s syndrome?

A

Karyotype 47, XXY

Two X’s in males

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2
Q

What is the cause of Kleinfelter’s syndrome?

A

IT IS NOT INHERITED

One extra copy of the X chromosome in each cell (XXY), the most common cause

An extra X chromosome in some of the cells (mosaic Klinefelter syndrome), with fewer symptoms

More than one extra copy of the X chromosome, which is rare and results in a severe form

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3
Q

What are the symptoms of Klinefelter’s syndrome?

A
  1. Often taller than average
  2. Lack of secondary sexual characteristics
  3. Small, firm testes
  4. Infertile
  5. Gynaecomastia - increased incidence of breast cancer
  6. Elevated gonadotrophin levels but low testosterone
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4
Q

How do you diagnose Kleinfelter’s syndrome?

A

Karyotype

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5
Q

What is the treatment for Klinefelter’s syndrome?

A
  1. Testosterone replacement therapy
  2. Breast tissue removal
  3. Speech and physical therapy
  4. Educational evaluation and support
  5. Fertility treatment
  6. Psychological counseling
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6
Q

WHAT IS TUNER’S SYNDROME?

A

X chromosomes (sex chromosomes) is missing or partially missing

A girl with Turner syndrome only has one normal X sex chromosome, rather than the usual two.

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7
Q

What are the causes of Turners syndrome?

A

Monosomy
The complete absence of an X chromosome

Mosaicism
This results in some cells in the body having two complete copies of the X chromosome

X chromosome abnormalities
Abnormal or missing parts of one of the X chromosomes can occur

Y chromosome material

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8
Q

What are the symptoms of Turners syndrome?

What age is it diagnosed?

A
  1. Shorter than average
  2. Underdeveloped ovaries
  3. Shield chest, widely spaced nipples
  4. Webbed neck
  5. Bicuspid aortic valve (15%), coarctation of the aorta (5-10%)
  6. Primary amenorrhoea

Diagnosed
8 - 14 years old

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9
Q

How do you diagnose Turners syndrome?

Hormone levels?

What body?

A
  1. Raised FSH and LH
  2. Low oestrogen
  3. Demonstration of the 45,XO karyotype is confirmatory, as is absence of the Barr body
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10
Q

What is the treatment of Turners Syndrome?

A
  1. Growth hormone - increase height
  2. Oestrogen therapy - promote breast development and increase uterus size
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11
Q

What is Downs syndrome?

A

Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21

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12
Q

What is the cause of Down syndrome?

A

NOT INHERITED

Trisomy 21
About 95 percent of the time, Down syndrome is caused by trisomy 21 — the person has three copies of chromosome 21

Mosaic Down syndrome
In this rare form of Down syndrome, a person has only some cells with an extra copy of chromosome 21

Translocation Down syndrome
Down syndrome can also occur when a portion of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception

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13
Q

What are the symptoms of Down syndrome?

A
  1. Flattened face
  2. Small head
  3. Short neck
  4. Protruding tongue
  5. Upward slanting eye lids (palpebral fissures)
  6. Unusually shaped or small ears
  7. Poor muscle tone
  8. Broad, short hands with a single crease in the palm
  9. Relatively short fingers and small hands and feet
  10. Excessive flexibility
  11. Tiny white spots on the colored part (iris) of the eye called Brushfield’s spots
  12. Short height
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14
Q

What are the complications of Down syndome?

A

Heart defects

Dementia

GI defects

Hypothyroidism

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15
Q

How do you diagnose Down syndrome?

A

First trimester
Blood test
Plasma protein-A (PAPP-A)
Human chorionic gonadotropin (HCG)

Ultrasound

  • Nuchal translucency test - specific area on the back of your baby’s neck
  • Double stomach bubble - duodenal atresia
  • Short femur

Second trimester
The quad screen measures your blood level of four pregnancy-associated substances: alpha fetoprotein, estriol, HCG and inhibin A.

Chrionic villus sampling

Amniocentesis

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16
Q

What is the treatment for Down syndrome?

A
  1. Primary care pediatrician to coordinate and provide routine childhood care
  2. Pediatric cardiologist
  3. Pediatric gastroenterologist
  4. Pediatric endocrinologist
  5. Developmental pediatrician
  6. Pediatric neurologist
  7. Pediatric ear, nose and throat (ENT) specialist
  8. Pediatric eye doctor (ophthalmologist)
  9. Audiologist
  10. Speech pathologist
  11. Physical therapist
  12. Occupational therapist
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17
Q

What is Edward’s syndrome?

A

Edwards’ syndrome, also known as trisomy 18, is a rare but serious condition.

Edwards’ syndrome affects how long a baby may survive. Sadly, most babies with Edwards’ syndrome will die before or shortly after being born.

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18
Q

What is the cause of Edward’s syndrome?

A
  1. 3 copies of chromosome number 18 instead of 2.
  2. Having 3 copies of chromosome 18 usually happens by chance, because of a change in the sperm or egg before a baby is conceived.
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19
Q

What are the different types of Edwards’ syndrome?

A

Full Edwards’ syndrome

Mosaic Edwards’ syndrome

Partial Edwards’ syndrome

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20
Q

What are the symptoms of Edwards’ syndrome?

A
  1. Micrognathia
  2. Low-set ears
  3. Rocker bottom feet
  4. Overlapping of fingers
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21
Q

How is Edward’s syndrome diagnosed?

Think pregnancy

A
  1. First trimester
    • Blood test
    • Plasma protein-A (PAPP-A)
    • Human chorionic gonadotropin (HCG)
    • Nuchal translucency test
  2. Second trimester
    • Alpha fetoprotein
    • Estriol
    • HCG
    • Inhibin A.
  3. Chrionic villus sampling
  4. Amniocentesis
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22
Q

What is the treatment for Edwards’ syndrome?

A

The major cause of death in many of these infants is sudden death due to neurological instability, cardiac failure, and respiratory failure

Treatment for infants who survive past this is mainly aimed at complications of the disease

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23
Q

What is Patau’s syndrome?

A

Patau’s syndrome is a serious rare genetic disorder caused by having an additional copy of chromosome 13 in some or all of the body’s cells. It’s also called trisomy 13.

13 Tau units

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24
Q

What is the cause of Patau’s syndrome?

A

NOT INHERITED

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25
Q

What are the symptoms of patau’s syndrome?

A
  1. Microcephalic, small eyes
  2. Cleft lip/palate
  3. Polydactyly
  4. Scalp lesions
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26
Q

How do you diagnose Patau’s syndrome?

A

First trimester
Blood test
This blood test measures the levels of pregnancy-associated plasma protein-A (PAPP-A) and the pregnancy hormone known as human chorionic gonadotropin (HCG)

Nuchal translucency test
During this test, an ultrasound is used to measure a specific area on the back of your baby’s neck

Second trimester
The quad screen measures your blood level of four pregnancy-associated substances: alpha fetoprotein, estriol, HCG and inhibin A.

Chrionic villus sampling

Amniocentesis

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27
Q

What is the treatment for Patau’s syndrome?

A
  1. Normally do not live long after birth
  2. For the small number of babies with Patau’s syndrome who survive beyond the first few days of life, their care will depend on their specific symptoms and needs.
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28
Q

What is fragile X syndrome?

A

Fragile X syndrome (FXS) is a genetic disorder characterized by mild-to-moderate intellectual disability

The average IQ in males is under 55, while about two thirds of females are intellectually disabled

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29
Q

What is the cause of fragile X syndrome?

A

Mutation of the fragile X mental retardation 1 (FMR1) gene on the X chromosome

Increase in the number of CGG trinucleotide repeats

30
Q

What are the symptoms of fragile X syndrome?

A
  1. Intellectual disability
  2. Long and narrow face
  3. Large ears
  4. Flexible fingers
  5. Large testicles
31
Q

How do you diagnose fragile X syndrome?

A

Genetic testing

32
Q

What is the management for fragile X syndrome?

A
  1. No specific cure
  2. Services can include therapy to learn to talk, walk, and interact with others
33
Q

What is cycstic fibrosis?

A

Cystic fibrosis (CF) is an inherited disorder that causes severe damage to the lungs, digestive system and other organs in the body.

34
Q

What is the cause of cystic fibrosis?

A

In cystic fibrosis, a defect (mutation) in a gene — the cystic fibrosis transmembrane conductance regulator (CFTR) gene — changes a protein that regulates the movement of salt in and out of cells

35
Q

What are the symptoms of cystic fibrosis?

A

Respiratory signs and symptoms
A persistent cough that produces thick mucus (sputum)
Wheezing
Exercise intolerance
Repeated lung infections
Inflamed nasal passages or a stuffy nose
Recurrent sinusitis

Digestive signs and symptoms
Foul-smelling, greasy stools
Poor weight gain and growth
Intestinal blockage, particularly in newborns (meconium ileus)
Chronic or severe constipation, which may include frequent straining while trying to pass stool, eventually causing part of the rectum to protrude outside the anus (rectal prolapse)

36
Q

What are the complications of cystic fibrosis?

A
  1. Bronchiectasis
  2. Diabetes
  3. Infertility
  4. Liver disease
  5. Osteoporosis
  6. Cor pulmonale
37
Q

How do you diagnose cystic fibrosis?

A
  1. Sweat test
    • Patient’s with CF have abnormally high sweat chloride
    • Normal value < 40 mEq/l, CF indicated by > 60 mEq/l
38
Q

What is the treatment for cystic fibrosis?

A

Preventing and controlling infections that occur in the lungs

Removing and loosening mucus from the lungs
Chest physical therapy
Nebulisers

Treating and preventing intestinal blockage

Providing adequate nutrition
High calorie diet, including high fat intake

39
Q

What is myotonic muscular dystrophy?

A

Muscular dystrophy is a group of diseases that cause progressive weakness and loss of muscle mass.

In muscular dystrophy, abnormal genes (mutations) interfere with the production of proteins needed to form healthy muscle.

40
Q

What is the cause of myotonic muscular dystrophy?

A

Autosomal Dominant Chromosome 19

41
Q

What are the symptoms of myotonic muscular dystrophy?

A

In the face:

  1. Frontal baldness
  2. Myopathic face with ptosis, hanging jaw, wasting of muscles of masticatio
  3. Cataracts in 80% of cases

In the limbs:

  1. Characteristic is the inability of the patient to let go of the examiner’s hand when they shake hand
  2. Percussion myotonia - via tapping over the thenar eminence - may result in contraction and slow relaxation of opponens pollicis
  3. Wasting and weakness distally
42
Q

How do you diagnose myotonic muscular dystrophy?

A
  1. Slightly raised CPK enzyme levels
  2. Conduction abnormalities on ECG
  3. Characteristic myopathic EMG, with so-called dive bomber noise
  4. Cataracts may be seen by slit lamp examination
  5. If urinary glucose is positive, it is followed by glucose tolerance test to confirm diabetes
43
Q

What is the management for myotonic muscular dystrophy?

A

Membrane stabilisers to reduce myotonia, including procainamide, phenytoin, quinine, quinidine, acetazolamide

Identification and treatment of cataracts and diabetes mellitus

Genetic counselling

Avoiding sedative drugs as sensitivity is increased

44
Q

What is duchenne muscular dystrophy?

A

Duchenne muscular dystrophy is a common and possibly the best known muscular dystrophy. It follows an aggressive and progressive course.

45
Q

What is the cause of duchenne muscular dystrophy?

A

X-linked disease

Xp21

46
Q

What are the symptoms of duchenne muscular dystrophy?

A
  1. Dilated cardiomyopathy
  2. Delayed walking - after 18 months
  3. Not running by age 3
  4. lordotic waddling gait
  5. Gower’s sign
  6. Weakness is symmetrical
  7. Wasting of most muscles but pseudohypertrophy of the calves
  8. Episodes of myoglobinuria (cola coloured urine)
  9. ALT or AST High
  10. Learning difficulties and behavioural issues
  11. Speech and language delay
  12. Autistic spectrum disorder
47
Q

What are the investigations for duchenne muscular dystrophy?

A
  1. Genetic testing has now replaced muscle biopsy as the way to obtain a definitive diagnosis
  2. Serum creatine kinase 30 to 200 times higher than normal
48
Q

What is the management for duchenne muscular dystrophy?

A
  1. Corticosteroids - improve muscle function and prolong ambulation, stop cardiac and lung disease
  2. Walking aids
  3. Prophylatic ACEI - high survival and lower hospitalisaiton
  4. Surgery to cut tendons and prevent disabiling contractures
49
Q

What is Angelman’s syndrome?

A

Angelman syndrome is a genetic condition that affects the nervous system and causes severe physical and learning disabilities

50
Q

What is the cause of Angelman’s syndrome?

A

Deletion of maternal chromosome 15

51
Q

What are the symptoms of Angelman’s syndrome?

A

Severe mental retardation without speech

Microcephaly

Flat occiput - brachycephaly

Jerky ataxic movements with broad based gait

Smiling face

Gales of inappropriate laughter

52
Q

How do you diagnose Angelman’s syndrome?

A
  1. Clinically
    Problems with movement and balance, a small head size, flatness in the back of the head, and frequent laughter
  2. Parental DNA pattern
    This test, known as a DNA methylation test, screens for three of the four known genetic abnormalities that cause Angelman syndrome.
  3. Missing chromosomes
    A chromosomal microarray (CMA)
  4. Gene mutation
53
Q

What is the treatment for Angelman’s syndrome?

A

Anti-seizure medication to control seizures

Physical therapy to help with walking and movement problems

Communication therapy, which may include sign language and picture communication

Behavior therapy to help overcome hyperactivity and a short attention span and to aid in development

54
Q

What is Prader-Willi syndrome?

A

Prader-Willi syndrome is a rare genetic condition that causes a wide range of physical symptoms, learning difficulties and behavioural problems.

It’s usually noticed shortly after birth.

55
Q

What is the cause of Prader-Willi syndrome?

A

Prader-Willi syndrome is a genetic disorder, a condition caused by an error in one or more genes

Problem lies in the genes located in a particular region of chromosome 15

56
Q

What are the symptoms of Prader-Willi syndrome?

A
  1. Hypotonia
  2. Hypogonadism
  3. Obesity
57
Q

How do you diagnose Prader-Willi syndrome?

A

Genetic testing

58
Q

What is the treatment for prader-willi syndrome?

A
  1. Good nutrition + weight management
  2. Human growth hormone treatment
  3. Sex hormone replacement
59
Q

What is Noonan syndrome?

A

Defective gene on chromosome 12

60
Q

What is the cause of noonan syndrome?

A

Inherited
Children who have one parent with Noonan syndrome who carries the defective gene (autosomal dominant) have a 50 percent chance of developing the disorder.

Random
Noonan syndrome can develop because of a new mutation in children who don’t have a genetic predisposition for the disorder (de novo).

61
Q

What are the symptoms of noonan syndrome?

A
  1. Webbed neck
  2. Pectus excavatum
  3. Short stature
  4. Pulmonary stenosis
62
Q

How do you diagnose noonan syndrome?

A

Hard to identify

May not be until adulthood until it is diagnosed

63
Q

What is the treatment for noonan syndrome?

A
  1. Heart treatment
  2. Treating low growth rate
  3. Addressing learning difficulties
  4. Vision and hearing treatments
  5. Treatment for bleeding and bruising
64
Q

WHAT IS WILLIAMS SYNDROME?

A

Abnormal development of the neural crest

Leading to a typical elfin facies and hypercalcaemia caused by gastrointestinal calcium absorption.

Will-i-am A THE 7TH CALCIUM ELF

65
Q

What is the cause of Williams syndrome?

A

Williams syndrome is caused by a deletion, or missing piece, of a region on chromosome 7

66
Q

What are the symptoms of Williams syndrome?

A

Elfin-like facies

Characteristic like affect - very friendly and social

Learning difficulties

Short stature

Transient neonatal hypercalcaemia

Supravalvular aortic stenosis

ACYNOTIC

67
Q

How do you diagnose Williams syndrome?

A
  1. Chromosome 7 affects the elastin gene
  2. Blood test for elastin can tell you about the protein
  3. Fluorescence in situ hybridization (FISH)
68
Q

What is the treatment for Williams syndrome?

A
  1. Individuals with Williams syndrome should have a formal evaluation by a cardiologist.
  2. Individuals with elevated blood calcium levels may need to be seen by a nutritionist or followed by a nephrologist.
69
Q

What are examples of X-linked diseaes?

A
  1. Androgen insensitivity syndrome
  2. Becker muscular dystrophy
  3. Colour blindness
  4. Duchenne muscular dystrophy
  5. E
  6. F
  7. G6PD deficiency
  8. Haemophilia A,B
  9. Nephrogenic diabetes insipidus
70
Q

What are examples of autosomal dominant conditions?

A
  1. Ehlers-Danlos syndrome
  2. Familial adenomatous polyposis
  3. Hereditary haemorrhagic telangiectasia
  4. Hereditary spherocytosis
  5. Huntington’s disease
  6. Marfan’s syndromes
  7. Myotonic dystrophy
  8. Neurofibromatosis
  9. Noonan syndrome
  10. Osteogenesis imperfecta
  11. Retinoblastoma
  12. Tuberous sclerosis
  13. Von Willebrand’s disease*
71
Q

What are examples of autosomal recessive conditions?

A
  1. Congenital adrenal hyperplasia
  2. Cystic fibrosis
  3. Fanconi anaemia
  4. Friedreich’s ataxia
  5. Gilbert’s syndrome*
  6. Haemochromatosis
  7. Sickle cell anaemia
  8. Thalassaemias
  9. Wilson’s disease