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Pathology 3000 > Genetic Development - Final Exam > Flashcards

Genetic Development - Final Exam Flashcards

1
Q

Four main stages of prenatal development

A
  1. Preimplantation embryonic stage
  2. Germ layer formation
  3. Early organogenesis
  4. Definitive organogenesis
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2
Q

Preimplantation stage

A

First cleavage of zygote and blastocyst formation
Morula (16 cells, day 4)
Blastocyst (day 5)
Trophoblast (dedicated to placenta and extraembryonic tissue)

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3
Q

Germ layer formation

A

Embryo implants in endometrial wall of uterus
Gastrulation occurs after implantation, cells arrange into 3 cellular compartments
Axes of final body plan form

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4
Q

Germ layers

A
  1. Ectoderm
  2. Mesoderm
  3. Endoderm
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5
Q

Late organogenesis

A

Anatomical and funcitonal maturation of organs occur (4-8w)
Position and basic structures of all organs are now established and cellular components necessary for full development are not in place
Neural tube defects form at this stage

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6
Q

Causes of neural tube defects (3)

A
  1. Geographical
  2. Folic acid deficiency (very early on)
  3. MTHFR involved in genetic component of neural tube defects
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7
Q

Congenital defects

A 
Present at birth
Organs or other structures
Significant cause of infant death (20%)
Major cause of long term morbidity, intellectual disability, and other dysfunction
Major impact on public health
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8
Q

Congenital defect causes (5)

A
  1. 75% - unknown
  2. 20% - genetic
  3. 2% - chromosomal
  4. 2% - infectious
  5. 1% - chemical
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9
Q

What point of organogenesis is most susceptible to developmental defects?

A

First trimester

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10
Q

Developmental malformation causes (6)

A

Disturbances in development resulting in development malformations - morphological defect of an organ or larger part of body results from intrinsically abnormal developmental process

  1. Genetic factors
  2. Exogenous teratogens
  3. Chromosomal abnormalities
  4. Single-gene disorders
  5. Prenatal diagnosis
  6. Prematurity, birth injury, SIDS
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11
Q

Cleft lip

A

Incidence increased in some families

Inherited as multifactorial trait

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12
Q

Achondroplastic dwarfism

A

Cause by single gene defect

Mendelian trait

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13
Q

Exogenous teratogens (3)

A
  1. Physical (X-rays, corpuscular radiation)
  2. Chemical (industrial, drugs, alcohol)
  3. Microbial (viruses, bacteria, protozoal parasites)
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14
Q

Fetal alcohol syndrome

A

Caused by prenatal exposure to alcohol
Intellectual and behaviour disabilities
Impairment of internal organs

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15
Q

TORCH syndrome

A

Toxoplasma
Others
Rubella
Cytomegalovirus
Herpes
Can stress mother and lead to low fetal weight
Marked by involvement of several organ systems

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16
Q

Other (TORCH)

A

Less common infectious agents

EBV, varicella virus, listeria monocytogenes, leptospira, etc

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17
Q

Brain (TORCH)

A

Most often affected

Small (microcephaly), mental retardation usually combined with neurological symptoms

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18
Q

Eyes (TORCH)

A

Small (micropthamlia), inflammation of inside layer of eyes, lens clouding

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19
Q

Heart (TORCH)

A

Development defect

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20
Q

Liver/lung (TORCH)

A

Inflammation, reactive enlargement of lymph nodes and spleen

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21
Q

Skin lesions (TORCH)

A

Petechial hemorrhages and vesicles

Especially after herpes virus infection

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22
Q

Congenital Rubella Syndrome

A 
Now prevented by maternal immunization
Marked by triad:
1. Microcephaly
2. Microphthalmia
3. CHD
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23
Q

Chromosome disorders

A

Clinical condition caused by abnormal chromosome constitution in which there is duplication, loss or rearrangement of chromosomal material
Structural or numerical

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24
Q

What is a chromosome?

A 
1/3 DNA
1/3 RNA
1/3 Protein
Coloured body
Threadlike structures seen in cell nucleus containing chromatin
Single molecular DNA in interphase state
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25
Q

What do chromosomes do?

A

Carry genetic information in a defined structure
Somatic cell division
Gamete formation

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26
Q

How do we study chromosomes?

A

Stained to give regular lines

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27
Q

Aneuploidy

A

Any chromosome number that is not an exact multiple of haploid number
Gain or loss of entire chromosome

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28
Q

Hyperdiploidy

A

2n+

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29
Q

Hypodiploidy

A

2n-

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30
Q

Monosomy

A

Loss of a single chromosome

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31
Q

Trisomy

A

Gain of a single chromosome

32
Q

Trisomy 21 (Down’s Syndrome)

A 
Non-disjunction in M1
Mental retardarion
Unique facial features
Eye abnormalities
Gaping mouth and large tongue
Heart diseases
Intestinal defects
Hand abnormalities (shortened fingers, curved)
Abnormalities of toes (wide gap)
33
Q

Pathogenesis of sex chromosome abnormalities

A

More common in clinical practice

Less lethal and cause less fetal wastage

34
Q

Turner’s syndrome

A

Usually diagnosed at puberty, or at infancy with excessive webbing
Short stature, heart-shaped face, webbing of neck, heart disease, broad chest, cubitus valgus, streak ovaries, hypoplastic uterus, amenorrhea

35
Q

Klinefelter Syndrome

A 
Groups of chromosomal disorders where there is at least one extra X in male karyotype
OR translocation of SRY to XX
Tall, long arms and legs
Lack of beard, body hair and pubic hair
Gynecomastia (breasts)
Female-like hips
Testicular atrophy, infertility
36
Q

WAGR syndrome

A

11p12-p14 deletions - deletion of short arm
Wilms tumour of kidney
Aniridia
Genital malformations
Mental retardation
Results in loss of important genes, such as WT1 - deletion of chromosome 13 causing retinoblastoma (RB1)

37
Q

Reciprocal translocation

A

Transfer of one segment of one chromosome to another chromosome (two non-homologous chromosomes)
1/500 newborns

38
Q

Balanced reciprocal translocations

A

Generally no loss or gain of genetic information
Position change but no phenotypic consequences
Reproductive consequences

39
Q

Down’s Syndrome - Translocation form

A

4% have 46 chromosomes
Reciprocal translocation between chromosome 21 and another acrocentric chromosome (14 or 22)
No maternal age effect, but may be the result of familial translocation
Parental karyotypes required for follow up

40
Q

Robertsonian translocations

A

Rare form of chromosomal rearrangement that, in humans, generally occurs in the five acrocentric chromosome pairs, namely 13, 14, 15, 21 and 22

41
Q

Autosomal dominant disorders

A

Apparent in heterozygotes
Trait is expressed in every generation that carries dominant trait
Unaffected offspring of symptomatic carrier do not transmit trait

42
Q

Marfan’s syndrome

A

Autosomal dominant disease affecting connective tissue
Structural defect in fibrillin, causing connective tissue to be loose and disjointed
Elongated head, eye abnormalities, aortic aneurysm with dissection and exsanguination, floppy mitral valve, vertebral deformity, long fingers

43
Q

Familial hypercholesterolemia

A

Autosomal dominant disease affecting CVS
1/500
Mutation in LDL receptor
Lipid deposits in tissues, especially arteries
Accelerated atherosclerosis and coronary artery disease
Nodules in hands, not curable but manageable with strict, low fat diet
Statins can help

44
Q

Adult polycystic kidney disease

A

Autosomal dominant disease affecting kidney

45
Q

Wilm’s tumour

A

Autosomal dominant disease affecting kidney

46
Q

Huntington’s disease

A

Autosomal dominant disease affecting nervous system

47
Q

Neurofibromatosis

A

Autosomal dominant disease affecting nervous system

48
Q

Familial polyposis coli

A

Autosomal dominant disease affecting GI tract

49
Q

Autosomal recessive disorders

A

Gene is apparent only in homozygotes

50
Q

Cystic fibrosis

A

Autosomal recessive disorder
Disorder in Cl ion transport channel
Positive sweat chloride test and DNA testing
Many fluid in body are highly viscous
Affects pancreas, affecting absorption - failure to thrive
Fetal intestines
Can be detected by ultrasound
Lungs start to fill up with viscous fluid, increased chance of bronchitis and pneumonia

51
Q

Anemias

A

Sickle cell anemia, thalassemia

Autosomal recessive disorder

52
Q

Lipodoses

A

Tay-Sachs disease, Niemman-Pick disease

Autosomal recessive disorder

53
Q

Mucopolusaccharidoses

A

Hurler’s syndrome
Hunter’s syndrome
Autosomal recessive disorder

54
Q

Amino acid disorders

A

Phenylketonuria
Albinism
Autosomal recessive disorder

55
Q

Lysosomal storage diseases

A

Autosomal recessive disorder
Deficiencies in enzymes in intermediate metabolism
things accumulate in cells

56
Q

Phenylketonuria

A

Autosomal recessive disorder
Phenylpyruvic acid accumulation as phenylalanine does not get converted into tyrosine
Can only detect when children start eating phenylalanine
Slow, progressive, irreversible mental retardation

57
Q

Tay Sachs Disease

A

Autosomal recessive disorder
Increased substrates in vacuoles
Affects brain and eyes

58
Q

X-linked recessives

A

Gene effected is usually evident only in males, rarely in females
Gene is transmitted from asymptomatic, heterozygous mother
Son of female has 50% chance of being affected
>100 genes on X chromosome, many linked to important diseases

59
Q

Hemophilia A and B

A

Hereditory bleeding disorders
Mutations in genes involved in coagulation
Factor 8: 1/5000 males larger, more room for mutation),
Factor 9: 1/30000 males
50% inherited, 50% new mutations

60
Q

X-linked muscular dystrophy (2)

A
  1. Duchenne’s

2. Becker’s

61
Q

X-linked congenital immunodeficiencies (4)

A
  1. Agammaglobulinemia
  2. Wiskott-Aldrich syndrome
  3. X-linked immunodeficiency
  4. Lymphoproliferative disorders
62
Q

Fragile X syndrome

A 
X-linked recessive disorder
CGG triple nucleotide repeat
Most common mental retardation in males
1/1250 males
1/1200 female (carrier)
Normal number of repeats is 5-44
200 greater repeats is pathologic
63
Q

Multifactorial inheritance

A

Trait or disease is product of several genes
Inheritance cannot be explained in terms of Mendelian single-gene inheritance
Exogenous and endogenous factors influence expression of the trait and determine severity of the disease
Genes encoding trait or disease have dose effect
More severe form: more likely to transmit to offspring

64
Q

Ancephaly and Craniorachischisis

A

Multifactorial inheritance
Failure of neural tube to close
Complete absence of brain
Folic acid deficiency

65
Q

Diabetes type II

A

Multifactorial inheritance
50% of affected persons have relatives with diabetes
High incidence in populations with high rate of intermarriage
High concordance among monozygotic twins
Not entirely environmental

66
Q

Prenatal diagnosis

A

Many genetic diseases and chromosomal abnormalities can be diagnosed prenatally
Usually for highrisk pregnancies

67
Q

Techniques for prenatal diagnosis (4)

A
  1. Utrasonographic examination
  2. Chorionic villus biopsy (10-15w)
  3. Amniotic fluid analysis
  4. Maternal blood analysis
68
Q

Prematurity

A

<30w
<2500g
Immaturity <1500g

69
Q

Immaturity

A

<1500g
Anatomical and functionally immature - more noticeable in brain and lungs
Cannot survive without medical assistance
NICU

70
Q

Causes of prematurity (3)

A

5-10% pregnancies terminate prematurely

  1. Maternal factors
  2. Fetal factors
  3. Placental factors
71
Q

Maternal factors of prematurity (2)

A
  1. Malnutrition, smoking, substance abuse

2. Infection

72
Q

Fetal factors of prematurity (3)

A
  1. Infections
  2. Fetal malformations
  3. Genetic diseases
73
Q

Placental factors of prematurity

A

Placental insufficiency

74
Q

Neonatal respiratory distress syndrome

A

Immature Type II pneumocytes
Surfactant deficiency
Atelectasis, alveolar, endothelial injury of lungs
Hypoxia of the hyaline membrane

75
Q

Hypoxia of hyaline membrane

A

Can cause cerebral intraventricular hemorrhage

Hemorrhagic intestinal necrosis

76
Q

Birth injury

A

Various lesions caused by mechanical trauma

Skull fractures, intracranial hemorrhage, peripheral nerve injury, fractures of long bones

77
Q

Sudden infant death syndrome

A 
Sudden, unexpected death of infants 
Cause unknown
Maternal risk factors
Fetal risk factors
Most common cause of death beyond immediate neonatal period
2mo

Pathology 3000 (14 decks)

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