Genetics Flashcards

1
Q

What is the first, second and third most common inheritance pattern for Down’s Syndrome?

A

Non-dysjunction
Robertsonian Translocation (onto Chromosome 14)
Mosaicism

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

What chromosome is affected in Cri-du-chat?

A

Chromosome 5, (5p deletion)

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

What chromosome is affected in DiGeorge Syndrome?

A

Chromosome 22

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

What chromosome is affected in Charcot Marie Tooth Syndrome?

A

Chromosome 17

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

What are the manifestations of Down’s Syndrome in the face, eyes, ears, mouth, hands, feet, brain, spine, endocrine, lungs, heart, gastrointestinal, gynaecological and haematological?

A
  • Face: Flat facial features, flat occiput
  • Eyes: Brushfield spots, upward sloping palpebral fissures, prominent epi-canthal folds
  • Ears: Low set ears, Hearing loss, glue ear
  • Mouth: Protruding tongue
  • Hands: Single palmar crease
  • Feet: Widened sandal gap
  • Brain: Alzheimer’s, Learning Disabilities
  • Spinal: Altanto-axial instability
  • Endocrine: Hypothyroidism
  • Respiratory: Respiratory infections
  • Cardiac: ASD, VSD, PDA, Tetralogy of Fallot
  • Gastrointestinal: Hirschprung’s Disease, Duodenal atresia
  • Gynaecological: Subfertility
  • Haematological: Acute Lymphoblastic Leukaemia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are all the Antenatal Screening tests for Down’s Syndrome?

A
  1. Combined
  2. Triple
  3. Quadruple
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Outline the Combined test for Down’s Syndrome

  • When is it performed?
  • What does it test?
A

Performed at 11-14 weeks gestation

Comprises the Ultrasound & Maternal Blood Test

  1. Ultrasound, increased nuchal translucency >6mm
    2a. Beta-hCG, higher result, greater risk
    2b. PAPP-A, lower result, greater risk
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Outline the Triple test for Down’s Syndrome

  • When is it performed?
  • What does it test?
A

Performed at 14-20 weeks gestation

Comprises only Maternal Blood Tests

1a. Beta-hCG, higher result, greater risk
1b. Serum Oestriol, lower result, greater risk
1c. AFP, lower result, greater risk

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

Outline the Quadruple test for Down’s Syndrome

  • When is it performed?
  • What does it test?
A

Performed at 14-20 weeks gestation

Comprises only Maternal Blood Tests
1a. Beta-hCG, higher result, greater risk
1b, Serum Oestrial, lower result, greater risk
1c, AFP, lower result, greater risk
1d. Inhibin-A, higher result, greater risk

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

Once Antenatal Screening Down’s Syndrome tests have been performed, what is done with the result?

A

Screening tests will give a risk score for the foetus having Down’s Syndrome. If risk > 1 in 150, will be offered CVS (if before 15 weeks) and Amniocentesis (later in pregnancy)

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

What is Klinefelter’s Syndrome?

A

Hypergonadotrophic Hypogonadism, 47XXY

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

What are some features of Klinefelter’s Syndrome?

A
Small testicles
Weaker muscles
Weak bones 
Gynaecomastia
Wide hips
Tall height
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the hormonal test results of Klinefelter’s Syndrome?

A

Increased LH, FSH, reduced Testosterone

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

What are patients with Klinefelter’s at an increased risk of?

A

Diabetes
Osteoporosis
Breast Cancer

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

What is the treatment for Klinefelter’s?

A

Testosterone Injections

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

What is the Karyotype for Turner’s Syndrome? What is the most common genetic mutation?

A

45,XO, commonly due to non-dysjunction

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

What is the clinical presentation of Turner’s Syndrome with respect to height, face, neck, endocrine, heart, chest, arms, hands, feet, renal, gynaecological

A
Height: Short stature
Face: Low set, ears
Neck: Webbed, Cystic Hygroma
Endocrine: Hypothyroidism
Heart: Coarctation of Aorta, Bicuspid Valve
Chest: Broad chest, Widely spaced nipples
Arms: Cubitus valgus
Hands: Lymphadema, short 4th metacarpal
Feet: Lymphadema 
Renal: Horseshoe kidney 
Gynaecological: Primary Amenorrhoea
18
Q

What are the features of Noonan Syndrome? 5, 4, 4

A

5, 4, 4

5: Webbed Neck, Triangular face, Short stature, Pectus Excavum, Undescended Testis

4 HIPA:
Hypertrophic cardiomyopathy
Infundibular Pyloric Stenosis
Pulmonic Stenosis, Pulmonary HTN
Atrial Septal Defect 

4: Autosomal dominant, Strabismus, Downward Palpebral Fissure, Factor XI Deficiency

19
Q

What are the features of Patau Syndrome?

A

Microcephaly
Holoproscencephaly
Meningomyelocele
Omphalcele

Cutis aplasia
Microphthalmia
Polydactyl
Cleft lip palate
Rocker bottom feet
Cyclopsia
Nose missing + Proboscis
20
Q

What is the biggest risk factor for Patau Syndrome?

A

Advanced Maternal Age

21
Q

Fragile X is a mutation of which gene? What is the inheritance pattern?

A

FMR1 gene: Fragile Mental Retardation 1 gene

X-linked inheritance pattern

22
Q

Why are men always affected in Fragile X Syndrome and women variably affected?

A

Men are always affected because they only have one copy of the mutated FMR1 gene, whereas women have one normal copy of the FMR1 gene as well

23
Q

What cardiac problem is associated with Fragile X Syndrome?

A

Mitral Valve Prolapse

24
Q

What are features of Fragile X Syndrome?

A

Long narrow face, large ears, high arched palate, hypermobile joints, macro-orchidism, mitral valve prolapse, learning difficulties, autism, ADHD, seizures

25
Q

Describe the mutation of the FMR1 gene in Fragile X Syndrome

A

CCG Expansion repeats due to slipped mispairing. >200 repeats is diagnostic

26
Q

What does it mean when a patient is a pre-mutation carrier of Fragile X Syndrome?

A

They have between 55 and 200 CCG CCG repeats. This can cause Fragile X Associated Tremor Ataxia Syndrome or Primary Ovarian Insufficiency

27
Q

Prader-Willi Syndrome affects which Chromosome?

A

Chromosome 15

28
Q

Outline the genetics of Prader-Willi Syndrome

A

Prader-Willi Syndrome is a genetic condition thats affects genes on Chromosome 15. Regarding this gene, in normal cases the mother’s genes are epigenetically switched off due to methylation, meaning the father’s genes only contribute to the phenotype (imprinting). However, the father’s genes in PWS are micro-deleted (70%) of cases. In 30% of other cases, PWS is caused because the child inherits both switched off copies of maternal genes (Maternal uniparental disomy)

29
Q

What is the presentation of Prader-Willi Syndrome in:

Newborns, Infants and Childhood?

A

Newborns: HYPOTONIA, poor sucking reflex hence FTT. Narrow forehead, almond eyes, thin upper lip, downturned mouth, fairer softer skin prone to bruising

Infants: Insatiable hunger due to hypothalamic dysfunction

Childhood: Short stature, morbidly obese, T2D, obstructive sleep apnoea. learning difficulties / low IQ,

30
Q

What gene and what chromosome is affected in Angleman Syndrome?

A

UBE3A Gene, Chromosome 15

31
Q

Outline the genetics of Angleman Syndrome

A

Angelman syndrome is a genetic condition caused by loss of function of the UBE3A gene, specifically the copy of the gene that is inherited from the mother. This can be caused by a deletion on chromosome 15, a specific mutation in this gene or where two copies of chromosome 15 are contributed by the father, with no copy from the mother.

32
Q

Outline features of Angleman Syndrome

A

Fascination with water, shiny objects
Widely spaced teeth
Excessive positive affect
Inappropriate laughter

33
Q

Outline features of Cri-du-Chat Syndrome

A
Cat-like cry
Small round face
Large cheeks
Hypertelorism (widely spaced eyes)
Prominent supraorbital arches
Epicanthal folds
Dropped jaw
Dental malocclusion
34
Q

What are the dysmorphic features of Edward’s Syndrome in the face, hands, feet?

A

Face: Prominent Occiput, Microcephaly, Cleft lip palate, Micrognathia (small chin)

Hands: Overlapping fingers

Feet: Rocker bottom feet

35
Q

What is the prognosis of Edward’s Syndrome?

A

Most babies die before birth, those who survive birth will however die within weeks / months due to central apnoea and severe cardiac abnormalities

36
Q

Why do babies with Edward’s Syndrome have polyhydramnios?

A

Because they have oesophageal atresia, hence cannot swallow amniotic fluid

37
Q

What are some multi-organ manifestations (cardiac, renal, hepatic, respiratory, gastrointestinal) of Edward’s Syndrome?

A
Cardiac: ASD, VSD, PDA
Renal: Nephroblastoma, horseshoe kidney
Hepatic: Hepatoblastoma
GI: Oesophageal atresia, Omphalcele
Respiratory: Pulmonary hypoplasia
38
Q

What is the quatrad for Pierre-Robin Sequence / Syndrome?

A

Micrognathia (underdeveloped jaw), Glossoptosis (posterior displacement of tongue), Airway obstruction and Cleft palate deformity

39
Q

What are the features for William Syndrome?

A

Elfin facies, starburst eyes, sociable, short stature, and spaced teeth

40
Q

What are the four complications for William Syndrome? SAHH

A

Supravalvular Aortic Stenosis
ADHD
Hypertension
Hypercalcaemia

41
Q

What conditions are tested for with the Guthrie test? When is it performed, and when do results come?

A

My Middle Child Cried Since I Harshley Guthrie Pricked

Maple Syrup Urine Disease
Medium Chain Acyl-CoA Dehydrogenase Deficiency
Cystic Fibrosis
Congenital Hypothyroidism
Sickle Cell Disease
Isovaleric Acidaemia 
Homocysteinuria
Glutaric Aciduria Type 1
Phenylketonuria

Taken on days 5-9, and results come back in 6-8 weeks