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MyReview Step > Genetics 8: monosomies and trisomies > Flashcards

Genetics 8: monosomies and trisomies Flashcards

1
Q 
Describe these in terms of ratios. 
Meta centric chromosome
Submetacentric
Acrocentric
Telocentric
A

Metacentric is 50/50

Submetacentric is 60/40

Acrocentric 80/20

Telocentric 100/0

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2
Q

Give example of a monosomy and a partial monosomy

A

Monosomy: Turner syndrome, XO

Partial monosomy: cri du chat, deletion of the short arm of chromosome 5

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3
Q

Name 3 main trisomies

A

Trisomy 13 : patau
Trisomy 18: Edwards
Trisomy 21: downs

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4
Q

What is the MC cause of Turner syndrome?

A

Non disjunction

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5
Q

What is going on In Turner’s syndrome?

A

One X chromosome is missing

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6
Q

In turners ysndrome, 30% of people are mosaics, that means what genotypes?

A

Some cells are 46 XX, others are 45 X0

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7
Q

Short stature, webbed neck, low set hairline, ovarian dysgenesis (streak ovaries) because fatty tissue has replaced the ovaries, no menarche or ovulation in females , horshoe kidney, shortened 4th metacarpal

A

Turner’s Syndrome

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8
Q

Lymphedema of hands and feet in the neonate is suggestive of

A

Turner’s Syndrome

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9
Q

The ovaries of a patient with Tuner syndrome cannot make these two hormones

A

Estrogen and progesterone

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10
Q

Three cardiac afflictions that can affect patients with Turner syndrome

A

Predictable coartación of the aorta. PRE ductal
Bicuspid aortic valve
Aortic dissection in adulthood

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11
Q

What is the main sx of coartación of the aorta ?

A

Diminished femoral pulses compared to brachial pulses

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12
Q

How to treat turners syndrome?

A

Surgery to fix webbed neck
Fix her coartación
Estrogen for second characteristics
Could do IVFertulization for having kids

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13
Q

Partial deletion of short arm in chromosome 5. Most commonly seen as sporadic mutation.

A

Cri du chat syndrome

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14
Q

Abnormal development of the larynx and the nervous system,

A

Cri du chat

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15
Q

One year old with feeling problems, low birth weight, cognitive and speech delays,
Motor delays, aggression, hyperactivity, tantrums, excessive drooling, wide eyes, small head and jaw, cat-like squeal.

A

Cri du chat
Chromosome 5
MCC sporadic mutation

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16
Q

Chromosomes that can undergo robertsonian translocations

A

13, 14, 15, 21 and 22

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17
Q

Sx of patau, chromosome?

A

Low set ears. Polydactyly, abnormal palm patterns, clef palate, lip palate. Coloboma (hole in the eye)?, malformed or absent nasal septum (nose), ringers overlapping thumb, rocker bottom feet (not just seen in Edwards syndrome), abdominal wall defects like omohalocele (extruded but covered intestinal organs),
Chromosome, 13, trisomy 13

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18
Q

Second most common trisomy?

A

Trisomy 18, Edwards Syndrome

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19
Q

Most common trisomy?

A

Trisomy 21, downs.

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20
Q

Sx in Edwards Syndrome? Chromosome?

A

Trisomy 18
Sx: Low set and malformed ears, prominent occiput, micrognathia, microstomia, microcephaly, Arnold chiari y malformatio, severe mental retardation, delayed psychomotor development, clenched hands with overlapping fingers (fists), rocker bottom feet, short sternum, hypertonia, VSD, PDA in heart, in GI- meckels diverticulum, malrotation .

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21
Q

Most common chromosomal abnormality, 1 of 3 most common causes of mental retardation, meotic II non disjunction (increased risk with matarla age)

A

Down’s syndrome

22
Q

Triple test for Down’s syndrome during weeks 16-18 of gestation looks for low levels of which tree substances?

A

Low AFP
Low B- hCGH
Low estradiol

23
Q

If low AFP found, then next step to Dx Down syndrome is to do what?

A

Amniocentesis is gold standard then karyotype

24
Q

What is a mosaic Down syndrome patient?

A

Their IQ is said to be 10-30 points higher. They will probably be able to function on their own, and Hold a simple job.

25
Q

Sx in Down’s syndrome

A

Low set ears, palpebral fissure (eyes), flat nasal bridge, muscle hypotonia, Simeon crease (single palmar fold), protruding tongue (due to small mouth), joint laxity (Atlanto- axial joint), wide space between the big and the second toe.

26
Q

Cardiac sx in Down’s syndrome

A

Present in up to 50% of patients.
Endocardium cushion defect (ASD is most common)
VSD is second most common.

27
Q

What two hematologic/cancer conditions are patients of Down’s syndrome most at risk?

A

AML (M7) after 12 years old, I,e, sometime in their lifetime
And
From birth to 12 years old, ALL (10 to 20x increased risk)

28
Q

What immunological maladies are patients with Down’s syndrome most prone to?

A

Impaired cellular immunity
High incidence of infections
High incidence of autoimmune disorders and malignancies

29
Q

What type of cells are seen most in AML?

A

Auer rods

30
Q

What organ specific findings are seen in Down’s syndrome?

A

Atherosclerosis risk is increased leading to neuropathies.

31
Q

What endocrine maladies am Down syndrome patients have?

A

MOs common is hypothyroidism. Buy hyper is also possible. Also
Type 1 DM
Infertility in males
subfertility in females 30-50%

32
Q

What are the most important neurological risks in patients with Downs syndrome?

A

They have an extra copy of the APP gene on chromosome 21. So they are at risk for early Alzheimer’s. Early means before 60. So accumulation of A beta amyloid in brain tissue and vessels.
And
Mental retardation, hearing impairment.

33
Q

What are the GI afflictions most likely in a patient with Down’s syndrome? Name 6

A 
Hirschsprung disease.
Duodenal atresia
Annular pancreas
Imperforate anus
GERD
Celiac disease
34
Q

What’s the most common karyotype of kilnefelters disease?

A

47 XXy

35
Q

What is the physical appearance in a person with klinefekter?

A

Eunuchoid body habitus : tall, gynecomastia, no secondary characteristics male , mild mental retardation. But majority have NORMAL intelligence, Absence of body hair, absence of facial hair, muscle mass is decreased.

36
Q

What are two variations of klinefeter karyotype?

A

48 XXXY

46XY/46 XXY mosaic

37
Q

Phenotypically this neonate is normal. Signs of this disease are evident in liberty. Hyooginadism. Reduced soermatigenesis, male infertility

A

Klinefekter Syndrome

47 XXY

38
Q 
Klinefekter sx:
Testicular?
FSH?
LH?
Testosterone?
Size of testes?
 Sexual characteristics?
A 
Testicular failure
No testosterone synthesis
FSH and LH are increased 
Testes Small, firm
Azoospermia, infertility, 
No secondary characteristics
39
Q

In Klinefelter syndrome the more —- the patients have, the more severe the retardation.

A

The more X chromosomes the more severe the mental retardation.

40
Q

Deletion of long arm of chromosome 22

A

DiGeorge Syndrome

41
Q

Sx of di george

A

Thrymic aplasia, failure of parathyroid, cardiac afflictions

42
Q

Sx in di George are caused by defective embryonic development of

A

3rd and 4th pharyngeal pouches

43
Q

Immunological consequence of thymus aplasia

A

No T cells, viral infections risk increases a lot.

44
Q

Hypocalcemia tetany, recurrent viral and fungal infections, y cardiac defects such as tetralogy of fallot, Clift palate

A

Di george

45
Q

Mental delays, hand flapping, frequent smiling, happy de años, genes maternally inherited

A

Angelman, chromosome 15

46
Q

Short stature, hypotonia, marrow temples, elongated face, thing upper lip, prominent nose, hyperphagia, severe obesity, increased risk for DM, hypodevelooment of sxual organs, 50-70 IQ, imprinting or deletion of paternal all chromosome

A

Chromosome 15, Prader willi syndrome

47
Q

What is early onset Alzheimer’s?

A

Less than 60 years old

48
Q

Three mutations associated with EARLY Alzheimer’s disease?

A
  1. APP gene on Chr 21
  2. Presenillin 1 gene on chr 14
  3. Presenillin 2 gene in chr 1
49
Q

Mutation associated with LATE Alzheimer’s disease?

A

APO e4 allele of the Apoprotein E - causes senile plaques

50
Q

Senile plaques are ——- the cell

A

Extra cellular

51
Q

Neurofibrillary tangles are —— the cell

A

Intro cellular

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