congenital/genetic disorders

Question 1

what is a congenital disorder

Answer 1

• “birth defect”
• result of developmental errors in embryo manifesting at birth
• present at birth, non-genetic

Question 2

what is the period of vulnerability

Answer 2

a time in gestation when the embryo is most sensitive to developmental errors

Question 3

organogenesis

Answer 3

period 15-60 days post-conception when organs begin to form

Question 4

teratogen

Answer 4

any factor responsible for congenital abnormalities

ex. drugs, smoking, alcohol, malnutrition, infection

Question 5

critical period for the CNS

Answer 5

2-5 weeks

Question 6

critical period for the heart

Answer 6

2.5-5.5 weeks

Question 7

critical period for the extremities

Answer 7

3.5-7 weeks

Question 8

critical period for the eyes

Answer 8

3.5-7.5 weeks

Question 9

critical period for the external genitalia

Answer 9

6.5-9 weeks

Question 10

types of genetic abnormalities

Answer 10

• monogenic
• complex trait
• mitochondrial
• chromosomal

Question 11

what is a monogenic abnormality

Answer 11

a single allele is affected; 3 types:

• autosomal dominant
• autosomal recessive
• x-linked recessive

Question 12

autosomal dominant disorder

Answer 12

• monogenic abnormality
• only 1 defective allele needed for disease manifestation
• 50% probability

Question 13

autosomal recessive disorder

Answer 13

• monogenic abnormality
• requires both defective alleles for disease manifestation
• 25% affected, 25% unaffected, 50% carriers

Question 14

define autosomal

Answer 14

non-sex dominant chromosome

Question 15

x-linked recessive disorder

Answer 15

• monogenic abnormality
• associated w/ female (X) chromosome
• males more often affected (XY)
• females rarely experience affects d/t having XX, one is still normal
• carrier mother = 50% sons affected, 50% daughter carriers
• affected father = sons unaffected, all daughters carriers

Question 16

mitochondrial gene disorders

Answer 16

• maternal inheritance of mitochondrial genes (sperm lose mitochondria in tail)
• involved in ATP production
• code for enzymes involved in the respiratory chain (electron transport chain)
• cause neuromuscular defects d/t high requirement for oxidative metabolism (more ATP)

Question 17

complex trait disorders

Answer 17

• polygenic and environmental factors
• is a predisposition
• not caused by predisposition alone, must be paired with environmental factors

Question 18

define polygenic

Answer 18

caused by multiple genes

Question 19

how many mitochondrial genes are there

Answer 19

37

Question 20

how many chromosomes are there

Answer 20

46 (23 pairs)

Question 21

chromosomal defects

Answer 21

defects in number or structure of chromosomes

Question 22

what is a karyotype

Answer 22

a test to identify and evaluate the size, shape, and number of chromosomes in a sample

Question 23

numeric chromosomal abnormality

Answer 23

• abnormal # chromosomes
• aneuploidy, trisomy, monosomy
• referred to by chromosome #
  ex. trisomy 21 = down syndrome

Question 24

aneuploidy

Answer 24

extra or missing chromosome

Question 25

trisomy

Answer 25

extra chromosome in a pair (3 total)

Question 26

monosomy

Answer 26

missing chromosome (1 total)
will not occur w/ autosomal chromosome b/c absence of 50% of genetic material is not conducive to life

Question 27

klinefelter’s syndrome

Answer 27

• trisomy, numeric problem
• male with additional X chromosome (XXY)
• 1 in 500
• manifestations: narrow shoulders, gynecomastia, wide hips, testicular atrophy, long arms/legs etc.

Question 28

turner’s syndrome

Answer 28

• monosomy, numeric problem
• female with only 1 X chromosome (XO)
• 1 in 2500
• manifestations: broad chest, webbed neck, poor breast development, hormone deficiencies, infertility

Question 29

structural chromosome abnormality

Answer 29

a section of the chromosome breaks off and does:

• inversion
• deletion
• translocation

Question 30

chromosome inversion

Answer 30

piece of the chromosome is inverted

• pericentric: around the centrosome
• paracentric: away from the centrosome

Question 31

chromosome translocation

Answer 31

piece of the chromosome transfers to another

• balanced: switch places
• Robertsonian: 1 long chromosome, 1 small that is lost
• isochromosomal: chromosomes split horizontally

Question 32

chromosome deletion

Answer 32

• part of the chromosome is missing
• leads to a loss of genetic material
• ring formation: following deletion, forms ring

Question 33

the word for extra or missing chromosomes

Answer 33

aneuploidy

Question 34

the word for an extra chromosome in a pair (3)

Answer 34

trisomy

Question 35

the word for missing a chromosome

Answer 35

monosomy