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Foundations > Genetics > Flashcards

Genetics Flashcards

1
Q

Locus

A

the specific location of a gene on a chromosome

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2
Q

Alleles

A

different versions of a gene, humans have 2 alleles for each autosomal gene

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3
Q

What is a gene?

A

hereditary units of DNA transmitted from one generation to another, code for proteins

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4
Q

What are homologous chromosomes?

A

chromosomes that have the same genes at the same loci; one maternal and one paternal

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5
Q

genome

A

genetic information, haploid set of chromosomes for a particular species

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6
Q

somatic cells

A

contain one set of chromosome from female parent and one homologous set from male parent

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7
Q

Haploid number?

A

n, the number of chromosomes in sex cells (n=23)

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8
Q

diploid number

A

2n, the total number of chromosomes in somatic cells (2n=46)

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9
Q

Name the 3 components of a chromosome

A

short arm (p)

centromere

long arm (q)

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10
Q

What are chromosomes except sex chromosomes called?

A

autosomes

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11
Q

What is a karyotype?

A

a pictures of a person’s chromosomes

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12
Q

mitosis

A

the process by which all somatic cells become descendants of one original cell. Original cell is divided into 2 daughter cells, producing exact copies

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13
Q

meiosis

A

process by which gametes cells are produced (egg and sperm)

2 consecutive cell divisions producing cells with half the original chromosome number

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14
Q

spermatogenesis

A

diploid primordial cells in testes become spermatogonia

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15
Q

oogenesis

A

diploid primordial ovaries become oogonia

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16
Q

What is codominance?

A

when 2 alleles for a trait are equally expressed (ex. AB blood type)

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17
Q

What is incomplete dominance?

A

heterozygotes have phenotypes that have both alleles visible as a blend (ex. wavy hair)

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18
Q

Penetrance

A

the probability that individuals in a population who have a particular gene combination will show the condition

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19
Q

Genetic marker

A

Sequence of DNA with a known location on a chromosome

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20
Q

Expression

A

the components of the phenotype that are exhibited in an individual (2 people with the same gene may express it differently)

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21
Q

Anticipation

A

genetic disease that increase in severity or have earlier onset with each generation (ex. Huntington)

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22
Q

What are balanced chromosomal abnormalities? Name the two types of balanced abnormalities

A

no net loss or gain of chromosomal material

Balanced translocation- ruptured chromosome, re-sticking in wrong combination

inversion- piece of chromosome flipped around and reinserted

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23
Q

Name the types of unbalanced chromosomal abnormalities

A

deletions
insertions
unbalanced translocation

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24
Q

Functions of 3 generation pedigree

A

Helps with:

  • making a dx
  • deciding on testing
  • establishing pattern of inheritance
  • identifying people at risk
  • educating pt
  • determining reproductive options
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25
Q

Describe the characteristics of autosomal dominant transmission

A

vertical pattern of transmission

multiple generations affected

variable expressivity

reduced penetrance

M/F equally affected

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26
Q

Autosomal Recessive

A

2 copies of diseased allele required for expressing the phenotype

rare

males and females equally affected

often occurs in the context of consanguinity

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27
Q

Describe the characteristics of autosomal recessive transmission

A

horizontal pattern

single generation affected

M/F equally

higher association with consanguinity

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28
Q

x-linked

A

no male to male transmission

males are usually more severely affected than females

“x-linked recessive” and “x-linked dominant” only apply to females

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29
Q

Multifactoral/complex disease

A

caused by interactions of variations in multiple genes and environmental factors

These genes make a person susceptible to a disorder and certain environmental factors trigger the susceptibility

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30
Q

Down syndrome

A

trisomy 21

most common chromosomal abnormality in live birth

increased incidence with advancing maternal age

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31
Q

What kind a testing can an expecting mother have to evaluate for down syndrome?

A

quad screening

nuchal translucency

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32
Q

What are the characteristics of down syndrome?

A

intellectual disability, characteristic facial appearance, increased social skills in childhood

some may have: cardiac defects, hearing loss, visual problems, GI defects, alzheimer disease in adulthood

33
Q

trisomy 18

A

Edwards syndrome

many die before birth or in first month

inter uterine growth restriction. 2% 1 yr survival rate

increased risk with advanced maternal age

34
Q

characteristics of trisomy 18

A

kidney and heart defects, developmental delay, club foot, low set ears, small jaw

35
Q

trisomy 13

A

Patau syndrome

increased risk with advanced maternal age

36
Q

characteristics of trisomy 13

A

severe intellectual disability, many physical abnormalities, cleft lip or palate, seizures, small jaw, polydactyly, heart defects, brain/spinal cord abnormalities

many children die within first days or weeks or life

37
Q

Cri-du chat syndrome

A

deletion of part of short arm of chromosome 5

partial monosomy

can be detected in utero with chorionic vila sampling

38
Q

define partial monosomy

A

when only a portion of a chromosome has one copy instead of two

39
Q

characteristics of cri-du-chat syndrome

A

cat like cry of affected children due to abnormal larynx development, intellectual disability, wide set eyes, low ears

40
Q

kleinflelter’s syndrome

A

Extra X chromosome, XXY

occurs during gametogenesis

affects male physical and cognitive development

accounts for many first trimester loses

41
Q

characteristics of Klinefelter’s syndrome

A

physical traits become more apparent after puberty

hypogonadism, infertility, gynecomastia (breasts in man), reduced hair

42
Q

turner syndrome

A

45 X, affects development in females

monosomy

43
Q

characteristics of turner syndrome

A

non-functional ovaries, short stature, broad chest, webbed neck, amenorrhea, infertility, cardiovascular abnormalities

44
Q

huntington’s disease

A

A neurodegenerative disease- progressive brain disorder that directly effects the nerves of the brain

autosomal dominant-only human disorder of complete dominance

adult onset: genetic defect is latent for 3-5 decades then manifests as progressive neuronal dysfunction

45
Q

characteristics of huntington’s disease

A

causes uncontrolled movements, emotional problems, loss of thinking ability, changes in personality

early signs: depression, irritability, poor coordination, trouble learning

46
Q

involuntary jerking movements associated with huntington’s disease?

A

chorea

47
Q

Which chromosome is the huntington’s disease gene located? What does it code for?

A

chromosome 4

codes for a unique protein called huntingtin: CAG trinucleotide repeat

abnormal protein causes microscopic deposits of protein in neurons

48
Q

Alzheimer’s disease

A

neurodegenerative disease, most common form of dementia in elderly

49
Q

familial alzheimer’s disease

A

aka early onset AD

symptoms onset before 65

mutations on chromosomes 1, 14, or 21

rare, autosomal dominant

50
Q

sporadic alzheimer’s disease

A

aka late onset AD

more common form

gene shown to increase risk: chromosome 19 apolipoprotein

definitive dx: autopsy-plaques and tangles

51
Q

What are the 2 major breast cancer susceptible genes?

A

BRCA1 on chromosome 17 and BRCA2on chromosome 13 (tumor suppressor genes)

52
Q

colorectal cancer

A

results from the interaction of both genetic and environmental factors

53
Q

Familial adenomatous polyposis

A

<1% of all colorectal cancers

mutation in APC gene

cancer develops in 20s

recommended: total colectomy

54
Q

Hereditary Nonpolyposis colorectal cancer (HNPCC)

A

aka lynch syndrome

autosomal dominant inheritance

mutation in one of the many genes that code for DNA repair

cancers occur in 30s and 40s

55
Q

chronic myelogenous leukemia

A

myeloproliferative disorder

more common in men

genetic defect: translocation between chromosomes 9 and 22

Philadelphia chromosome (22): produces a protein that codes for an enzyme that causes too many stem cells to develop into WBCs

56
Q

clinical presentation of chronic myelogenous leukemia

A

insidious onset, slow progression over months to years of infections, anemia, bleeding, fever, night sweats, fatigue

57
Q

Hemophilia

A

bleeding disorders caused by mutations in genes that code for coagulation proteins

58
Q

What mutation causes hemophilia?

A

mutation on F8 or F9 genes, located on the X chromosome

59
Q

What is the pattern of inheritance for hemophilia?

A

X-linked recessive pattern

60
Q

What are the clinical manifestations of hemophilia?

A

hemarthroses, bleeding into muscles and other soft tissues; prolonged bleeding or oozing of blood after injury or surgery

61
Q

sickle cell disease

A

atypical hemoglobin molecules (hemoglobin S), crescent shape

62
Q

clinical manifestations of sickle cell disease

A

anemia, infections, episodic pain, SOB, fatigue, delayed growth

63
Q

mode of inheritance of sickle cell disease

A

autosomal recessive

64
Q

cystic fibrosis genetic mutation

A

mutation in the CFTR gene(cystic fibrosis transmembrane conductance regulator)

65
Q

mode of inheritance for cystic fibrosis

A

autosomal recessive

66
Q

clinical manifestations for cystic fibrosis

A

thick, sticky mucous obstructing airways in lungs and ducts in pancreas

meconium ileus- newborn intestinal obstruction due to thick fecal waste products

67
Q

What is the most common cause of morbidity associated with CF?

A

pulmonary disease

68
Q

what is the primary test for cystic fibrosis dx?

A

sweat chloride test, defective chloride channel doesn’t allow chloride to be reabsorbed

69
Q

marfan syndrome mode of inheritance?

A

autosomal dominant

70
Q

mutation responsible for marfan syndrome

A

inherited mutation or a new mutation of the fibrillin-1 gene (FBN1) codes for connective tissue proteins

71
Q

clinical manifestations of marfan syndrome

A

tall stature, long thin arms and legs, arm span wider than body height, scoliosis, hyperflexible joints, overcrowded teeth

dislocated lens of the eye, AA/dissection

72
Q

Neurofibromatosis Type I

A

aka recklinghausen disease

autosomal dominant

mutation on NF1 gene on chromosome 17 (tumor supressor gene)

73
Q

manifestations of neurofibromatosis Type I

A

growth of neurofibromas-benign tumors that grow on nerves of skin and brain, changes in skin pigmentation (cafe au lait spots)

74
Q

What is the crowe sign seen in neurofibromatosis Type I?

A

axillary or inguinal freckles

75
Q

Polycystic Kidney disease

A

clusters of fluid filled sacs in kidneys, affects ability to filter the blood properly, they can become enlarged and fail

76
Q

clinical manifestations of polycystic kidney disease

A

HTN, back pain, hematuria, UTIs, kidney stones

77
Q

What are the two types of polycystic kidney disease?

A

autosomal dominant- sxs in adults

autosomal recessive-rare, lethal

78
Q

What is done during a newborn screening?

A

biochemical analysis that determines whether certain proteins are present or absent, checks for metabolic disorders

79
Q

when are the 2 tests for newborn screening performed?

A

1st: heel stick at 24-36 hrs
2nd: first office visit between 5-10days

Foundations (6 decks)

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