Ch. 5 Genetic and Congenital Disorders

Question 1

Congenital defects

Answer 1

may be caused by genetics or environmental factors

Question 2

allele

Answer 2

two members of a gene pair, 1 from mom, 1 from dad

Question 3

polymorphism

Answer 3

many genes have more than one normal allele at the same locus

Question 4

codominance

Answer 4

possible for both alleles of a gene pair to be phenotypically seen in a heterozygote

Question 5

Causes of birth defects

Answer 5

genetic factors: single or multifactorial inheritance or chromosomal aberrations
Environmental factors: maternal disease, infections, or tetragoenics
Intrauterine factors (rare0 fetal crowding, positioning, entanglement of fetal parts with the amnion)

Question 6

Amnion

Answer 6

inner membrane

Question 7

Chorion

Answer 7

outer membrane

Question 8

Single Gene Disorders

Answer 8

may be present on an autosome or x chromosome
may affect one member or both members of an autosomal gene inheritance
-family genetic history
-can be expressed differently in people
-wide variation of gene penetrance

Question 9

Results of Single Gene disorders

Answer 9

o Formation of an abnormal protein or decreased production of a gene product
o Defective or decreased amounts of an enzyme
o Defects in receptor proteins and their function
o Alterations in nonenzyme proteins
o Mutations resulting in unusual reactions

Question 10

Disorders of Single Gene Inheritance. Autosomal dominant

Answer 10

Marfan syndrome: connective tissue disorder that is manifested by changes in the skeleton, eyes and CV system. 70-80% are familial inheritance.
Neurofibromatosis: (NF). a condition in which tumors develop from schwann cells of neurologic system. two distinct forms. Type 1 and Type 2.

Question 11

Autosomal Recessive Disorders

Answer 11

:only when both members of the gene pair are homozygous. both parents may be unaffected but are carriers. characteristically caused by loss of function mutations.
PKU (phenylketonuria) disorder of deficiency of the liver enzyme phenylanaine hydroxylase, (which allows the conversion to tyrosine) allows toxic acid of phenyl to accumulate in tissues and blood.
Tay Sachs Disease: rare, absence of an enzyme that breaks down fatty substances (gangliosides) affects the function of the nerve cell

Question 12

X linked Recessive

Answer 12

males usually display the phenotype. regardless if dominant or recessive.
sons of of hetero women have 50% of recieving. expression in females is often variable
cause of spontaneous abortions
sex linked disorders are almost always the X chromosome.

Question 13

Fragile X Syndrome- dominant

Answer 13

chromatin fails to condense during mitosis. second most common cause of mental retardation after downs.
for females, mutant x is dom to normal x. often lethal to embryonic males
affected males will have 100% affected daughters and 100% normal sons

Question 14

Multifactoral inheritance disorders

Answer 14

caused by multiple genes and environment factors.
ex.Cleft lip or palate. Clubfoot. Congenital dislocation of the hip. Congenital heart disease. Pyloric stenosis .( Vomiting. Hypertrophy of pyloric sphincter. More common in males. Surgically fix. )Urinary tract malformation

Question 15

Results of Chromosomal disorders

Answer 15

Early gestation loss. congenital malformations. intellectual disabilities.

Question 16

Aneuploidy

Answer 16

abnormal amount of chromosomes.

Question 17

Monosomy

Answer 17

presence of only one member of the chromosome pair. (Turner syndrome) monosomy x

Question 18

Polysomy

Answer 18

presence of more than two chromosomes to a set (Kleinefelter) polysomy x

Question 19

Down syndrome

Answer 19

excess pair of chromosome.
increased risk with higher maternal age
95% are caused by nondisjunction or an error in cell division during meiosis

Question 20

Turners Syndrome

Answer 20

only females. one x is missing of partially missing. short height, failure of the ovaries to develop, heart defects

Question 21

Klinefelter syndrome

Answer 21

too many x chromosomes. male. hypogonadism, decreased body hair, gynecomastia, inc risk for breast cancer, typically tall with long arms and legs. lanky build.

Question 22

Mitchondrial DNA disorders

Answer 22

subject to mutations at a higher rate than nuclear DNA bc no repair mech.
commonly associated with neuromuscular disorders.
mtDNA) is packaged in a double-stranded circular chromosome and contains 37 genes: 2 ribosomal RNA genes, 22 transfer RNA genes, and 13 structural genes encoding subunits of the mitochondrial respiratory chain enzymes, which participate in oxidative phosphorylation and generation of adenosine triphosphate..always inherited from maternal line

Question 23

Teratogenic Agents

Answer 23

produce abnormalities during embryonic or fetal development.
radiation. chemical and drugs, infectious agents

Question 24

Periods of Fetal Development

Answer 24

CNS 3- Full Term
Eyes  41/2 to full term
Heart 3 ½ to 9
Lower limbs  4 ½ to 9
External Genitalia : 7 to full term
Ears  4 ¼ to 20
Teeth 6 ½ to full term
Palate 6 ½ to 16
Upper limbs 4 ½ to 9

Question 25

Pregnancy Categories

Answer 25

old: A-X (d-x has shown injury)
New: 8.1 pregnancy 8.2 lactation 8.3 females and males of reproductive potential

Question 26

When is a fetus most sensitive to radiation?

Answer 26

2-18 weeks.

Question 27

FAS

Answer 27

prenatal or postnatal retardation (below 100th percentile) neurologic abnormalities. developmental delays, behaviroal dysfunction, intellectual impairment, skull and brain malformation

Question 28

Cocaine

Answer 28

decreased blood flow, maternal hypertension, stimulation of uterine contractions, fetal vasoconstriction

Question 29

Vitamin A derivatives

Answer 29

synthetic retinoids. used to treat acne vulgaris. on BC for up to 3 years after taking regimen. cytotoxic, antimetabolic

Question 30

Folic Acid deficiency

Answer 30

up to 70% of all deficiencies are preventable.
Spina bifida (lower nerve exposed)
Anencephaly (no brain)
Encephalcocele (brain is outside crainum)

Question 31

Infectious Agents during pregnancy

Answer 31

TORCH
Toxoplasmosis, other, rubella, cytomegalovirus, herpes
2.5% incidence of these infections in live newborns

Question 32

Prenatal screening tests

Answer 32

tests can tell you the chance that your fetus has an aneuploidy and a few other disorders

Question 33

prenatal diagnostic tests:

Answer 33

can tell whether fetus actually has certain disorders. are done on the cells from the fetus or placenta through chorionic villus sampling or amniocentesis

Question 34

AFP (alpha-fetoprotein)

Answer 34

protein produced by fetus

Question 35

Estriol

Answer 35

estrogen produced by both the fetus and placenta

Question 36

Inhibin A

Answer 36

protein produced by the placenta and ovaries

Question 37

Quad Screen

Answer 37

perfromed between 16 and 18 wks, maternal screen, risk for down syndrome or neural tube defect

Question 38

cffDNA

Answer 38

present after 5-7 wks, tests for downs, patau syndrome, edwards syndrome, and problems with other sex chromosomes

Question 39

Edwards syndrome

Answer 39

severe developmental delays due to an extra chormosome 18. low birth weight, small abnormally shaped head, birth defects in organs that are often life threatening. has no treatment and is usually fatal before birth or within the first year of life.