Patho - Genetic and Congenital Disorders Flashcards

1
Q

what are genetic disorders?

A

-caused by single genes usually follow autosomal dominant, autosomal recessive, or x-linked recessive models of inheritance
-apparent at birth
-majority inherited from parents; some d/t fetal development mutations

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

what are chromosomal aberrations?

A

Abnormality in structure/number of chromosomes. Leading cause of mental retardation & miscarriage Incidence of chromosomal abnormalities
-1/12 conceptions
-Approx. 95% of conceptions result in miscarriage
-50% of 1st trimester miscarriages associated with major chromosomal abnormality
-1/150 live births with major diagnosable chromosomal abnormality

Causes Risk factors: poorly understood
1. advanced maternal age
2. abnormalities in prenatal genetic structure
3. abnormalities in meiosis

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

what is trisomy 21 (down syndrome)?

A

-extra copy of 21st chromosome
-most common chromosomal disorder
-leading cause of intellectual disability
-protruding tongue, low-set ears, epicanthal folds, poor muscle tone, short stature; congenital heart deformities, increased susceptibility to respiratory infections, leukemia, memory loss
-associated with advanced maternal age

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

what is klinefelter syndrome?

A

-most common genetic disease of sex chromosomes
-affects males, usually 1 extra X chromosome (xxy genotype)
-lack of secondary sex characteristics during puberty

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

what symptoms are associated with klinefelter syndrome?

A

-lack of testosterone
-testicular atrophy; infertility
-feminine hair distribution/gynecomastia (enlargement of breast tissue)
-tall stature, long arms/legs
-high-pitched voice
-impaired intelligence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is turner syndrome (monosomy X)?

A

-1 normal X chromosome; no Y chromosome
-1:3000 births
-female phenotype with no functioning ovaries
-2nd X chromosome missing or structurally abnormal; usually d/t father’s advanced age
-short stature, webbed neck, fibrous ovaries, sterility, amenorrhea, wide chest, congenital heart defects
-no mental retardation - live fairly normal lives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is mendelian single-gene disorder?

A

-Alterations or mutations of single genes
-Pedigree may help trace transmission through the family
-Classified according to location of defective gene and mode of transmission
1. autosomal dominant
2. autosomal recessive
3. sex-linked (X-linked)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is marfan syndrome?

A

-Connective tissue disorder
-Tall, slender; long, thin arms/legs & fingers
-Cardiovascular lesions most threatening
-Aorta usually weak, susceptible to dilation/rupture

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

what are the three autosomal recessive disorders? what are they?

A

Albinism: lack of pigmentation from disrupted melanin synthesis
Phenylketonuria: Inborn error of metabolism -cannot metabolize phenylketonuria - test at birth
Cystic fibrosis: most common –
thick secretions d/t lack of chloride transport across

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

what are sex-linked (X-linked) disorders?

A

-Inherited mutation of sex chromosome (almost always X)
-Nearly all X-linked disorders are recessive
-males always express disease and females rarely affected (since males are XY)

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

what is non mendelian single-gene disorder?

A

-caused by long triplet repeat mutations, ie; fragile X syndrome
-d/t mitochondrial DNA mutations
-associated with genomic imprinting

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

what is fragile X syndrome?

A

-premutation: possible to have intermediate number of inherited repeats which increase the risk of mutation
-males more severely affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are multifactorial (polygenic) disorders?

A

-interaction of multiple gene
-very common
-“run in families”
-also present range of severity
-difficult to predict based on family history
-multifactorial disorders– high blood pressure, cancer, diabetes
-multifactorial traits– height, weight, intelligence

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

what are environmentally induced congenital disorders?

A

-errors in fetal development that result in congenital malformations
-numerous environmental influences (teratogens) may adversely affect developing fetus

teratogenic agents:
-chemical and drugs (alcohol)
-infectious agents (viruses, rubella)
-radiation

-susceptibility depends on amount of exposure, developmental age, and teratogen
-may produce death, retardation, malformation, or functional impairment

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

what are the periods of fetal vulnerability in environmentally induced congenital disorders?

A

-before 3rd gestational week: teratogen exposure either damages very few cells or so many that embryo cannot survive
-3rd to 9th week: embryo very susceptible to teratogenesis (especially 4th and 5th weeks during organ development)
-after 3rd month, teratogens affect growth or injury to already formed organs

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

what are some examples of prenatal diagnosis and couseling?

A

-ultrasound
-amniocentesis
-chorionic villus sampling
-embryoscopy

17
Q

what is recombinant DNA therapy?

A

genetic engineering in which there is laboratory alteration of genes

18
Q

what is gene therapy?

A

exchange of abnormal gene for a normal gene, repair an abnormal gene through selective reverse mutation, and alter degree to which a gene is turned on and off in a particular gene