Single Gene Disorders

Question 1

single gene disorders caused by

Answer 1

defective allele at a single gene location that follows the mendelian patterns of inheritance

Question 2

mendelian patterns of inheritance

Answer 2

characteristic of organism that reproduce sexually; can only happen with single gene diseases : autosomal dominate, autosomal recessive, x-linked dominate, x-linked recessive, and mitochondrial

Question 3

patterns of inheritance depend on

Answer 3

phenotype (dominate or recessive) and whether the defective gene is on a autosomal or sex chromosome

Question 4

inheritance patterns of autosomal dominate and recessive disorders (single gene disorders)

Answer 4

only need on dominate chromosome for disorder to appear/ need two recessive
not on sex chromosome (#23)

Question 5

patterns of inheritance can be predicted using

Answer 5

punnett squares

Question 6

autosomal dominate disorders

Answer 6

a single mutant allele from an affected parent is transmitted to an offspring regardless of sex

Question 7

autosomal dominate disorders change of transmitting to each offspring

Answer 7

50% chance for the affected parent to transmit the autosomal dominate disorder to their offspring; unaffected relatives/siblings do not transmit the disorder

Question 8

many autosomal dominate disorders accompanied by

Answer 8

reduced repo capacity->therefore defect is not repeated in further generations

Question 9

% change of inheriting a autosomal dominate disorder

Answer 9

50% but wide variation of gene penetrance and expressions (reduced penetrance and variable expression)

Question 10

does sex matter in autosomal dominate disorders

Answer 10

no

Question 11

the affected parent has what percent change of transmitting the disorder to their offspring’s

Answer 11

50%

Question 12

what are the chances of a unaffected sibling transmitting a autosomal dominate disorder ?

Answer 12

0%; those not affected are not carriers and do not pass it along

Question 13

examples of autosomal dominate disorders

Answer 13

achondroplasia
adult polycystic kidney disease
Huntington's
familial hypercholesterolemia
marfan syndrome
neurfibromatosis
osteogenesis imperfecta
spherocytosis
von williebrand diease

Question 14

autosomal recessive disorders

Answer 14

manifest ONLY when both members of the gene pair are affected (child inherets homozygous)
=both parents must either be affected or be carriers of defective gene

Question 15

do autosomal recessive disorders only affect certain sexes?

Answer 15

no, not a sex linked gene (autosomal not sex chromosome) so sex doesnt matter

Question 16

autosomal recessive disorders: % change of having affected child=

Answer 16

1 in 4/ 25%

Question 17

autosomal recessive disorders % chance of having carrier child=

Answer 17

2 in 4/ 50%

Question 18

autosomal recessive disorders % change of having child not affected or not carrier

Answer 18

1 in 4 or 25%

Question 19

examples of autosomal recessive disorders

Answer 19

cystic fibrosis
glycogen storage disease
oculocutaneous albinism
phenylketonuria
sickle cell disease
tay sachs disease

Question 20

autosomal dominate disorder

Answer 20

inheriting two dominate alleles (one from each parent) can increase severity of disease vs one dominate- less severe disease

Question 21

sex linked disorders

Answer 21

are almost always associate w/ X chromosome; inheritance patters are predominantly recessive

Question 22

x-linked recessive disorders

Answer 22

genetic disorders linked to recessive x chromosome

Question 23

female chromosomes (refressher)

Answer 23

XX

Question 24

male chromosomes (refresher)

Answer 24

XY

Question 25

why do females rarely experience effects of the recessive X defective gene?

Answer 25

``` b/c females have 2-XX chromosomes, so have the presence of one normal X chromosome even with one defected aka heterozygous (carrier) females rarely experience affects of recessive def. gene ```

Question 26

males are typically affected more by x linked recessive defects because

Answer 26

males only inherit the one, defected X copy

Question 27

unaffected mother is carrier of mutant allele, she has normal x dominant and mutant recessive X; what is the chance she will pass along mutant gene to her son? daughtes?

Answer 27

son: 50% of being affected; he could get either the recessive or the dominate allele from the mother daughter: have 50% change of being carriers , 50% change of no affect,

Question 28

affected male with x linked recessive disorder-> passing to son? daughter?

Answer 28

if father has a daughter-> will transmit defective X to daughter-> carrier (only x available to donate) if has son-> will not be affected (father donates y chromosome)

Question 29

x linked dominate disorders

Answer 29

are not as common as x linked recessive disorders- | = defective X (sex linked) dominate chromosome

Question 30

x linked dominate disorders in females

Answer 30

mutant X is dominate to normal X so = affected

Question 31

x linked dominate affected females transmit to what % of their offspring? (heterozygous female)

Answer 31

will transmit 50% of the time; regardless of sex

Question 32

x linked dominate affected males will transmit- males/females

Answer 32

100% of daughters will be affected- daughters only inherit mutated x chrom from father 100% of males not affected (males only inherit y chrom)

Question 33

x linked dominate usually lethal for

Answer 33

embryonic male when inherited x linked dominate b/c ONLY have that one X linked dominate x chromosome or for homozygous females (both X chromosomes are x link dominate mutated)

Question 34

dominate sex linked disorders means

Answer 34

you only need one dominate affected x chromosome to be affected

Question 35

fragile X syndrome

Answer 35

x linked dominate, single gene disorder mutation occurs on Xq27 most common form of intellectual disability

Question 36

fragile x syndrome causes

Answer 36

intellectual disability; mostly affects brain/teste | long face w/ large mandible, large everted ears,

Question 37

fragile x syndrome in girls

Answer 37

more likely to be subtle or absent of phenotype presentations because girls have 2 X chrom (one normal) may show learning disability only in particular area

Question 38

multifactor inheritance disorders

Answer 38

caused by influence of multiple genes + environment factors

Question 39

inheritance patterns do not follow the same patterns as single gene disorders (T/F?)

Answer 39

true

Question 40

expression of multifactor inheritance disorder always occurs later in life (T/F)

Answer 40

false- can be present at birth or present later in life

Question 41

environmental factors play a significant role in development of multifactor inheritance disorders (T/F)

Answer 41

true

Question 42

multifactor inheritance disorders congenital malformations usually involve a single organ or tissue derived from the same embryonic developmental field

Answer 42

true

Question 43

risk of reoccurrence is high for future pregnancies after a child with multifactorial inheritance disorder

Answer 43

true

Question 44

cleft palate is an example of an inherited multifactor disorder

Answer 44

true

Question 45

chromosomal disorders

Answer 45

major category of genetic disease accounting for a large proportion of early miscarriages, congenital malformations, and intellectual disability

Question 46

study of chromosomal disorders is called

Answer 46

cytogenetics

Question 47

chromosomal disorders results in

Answer 47

abnormalities in number of chromosomes and/or structural alterations to 1 or more chromosome

Question 48

extra or structure alterations in chromosomal disorders usually result from

Answer 48

breakage in one or more of the chromosomes during meiosis followed by rearrangement or deletion of chromosome parts

Question 49

what factors cause breakage of chromosomes leading chromosomal disorder

Answer 49

exposure to radiation such as x-rays, influence of certain chemicals, extreme changes in the cellular environment and viral infections

Question 50

aneuploidy

Answer 50

having an abnormal # of chrom. usually due to a failure of chromosomes to separate during oogenesis or spermatogenesis: can occur in autosomes or sex chromosomes

Question 51

failure of chromosome to splits during oogenesis or spermatogenesis is called

Answer 51

nondisjunction

Question 52

down symdrome

Answer 52

most common chromosomal numeric disorder; there are still 46 chromosomes but TRISOMY happens at the 21st chromosome

Question 53

down syndrome manifestations

Answer 53

some degree of intellectual disability chara. facial features, health problems small sq. head, flat facial features, small folds in inner corner of eyes, upward slanting eyes, fat pad @ back neck, open mouth, large protruding tongue, short stubby fingers, usually congenital heart defects, increased risk of gastro malformations, increased risk of alzhiemers

Question 54

95% of down syndrome caused by what?

Answer 54

nondisjunction (or error in cell division during meiosis)

Question 55

rare form of down syndrome has error occur through

Answer 55

robertsonian translocation with trisomy of the long arm of chrom #21

Question 56

the risk of having a child with down syndrome increases with age (t/f)

Answer 56

true- rational is that womens are born with all their eggs which change over time due to aging process

Question 57

chromosomal numeric disorder linked to sex chromosomes

Answer 57

chromosomal disorders associated with sex chromosomes are much more common than those related to autosomes (except for down syndrome)

Question 58

characteristics of sex linked chromosomal numeric disorders

Answer 58

all but one X chromosome is inactivated | there are very few genes that are carried on y chromosome

Question 59

turner syndrome

Answer 59

x linked chromosomal numeric disorder; caused by absence of all or part of X chromosome (45,X/O); affects females

Question 60

manifestations of turner syndrome

Answer 60

1 in 2500 affected ; most frequently occuring genetic disorder in women = short in stature, normal body proport. lose majority of oocytes by age 2, do not menstruate and show no shows of secondary sex chara

Question 61

variations in turner syndrome

Answer 61

range from essentially normal phenotype to cardiac abnormalities and small webbed neck

Question 62

Klinefelter syndrome

Answer 62

numerical x-linked chromosomal abnormality where males have extra x chromosome on (47,xxxy)

Question 63

klinefelter syndromes frequency

Answer 63

1 in 700 male newborns

Question 64

klinefelter syndrome extra X chromosome results of

Answer 64

nondisjunction during meiosis division - can be result of advanced maternal age

Question 65

klinefelter syndrome manifestations

Answer 65

enlarged breasts sparse facial and body hair, small testes, inability to product sperm usually undetected until puberty when testes do not respond to gonadotropin-> degeneration may be deficient in 2ndry male sex hara may have some degree of language impairment

Question 66

environmental influences of chromosome disorders happen during

Answer 66

period of vunerability

Question 67

period of vulnerability

Answer 67

cell differentiation and organ development happen 15-60 days after conception-> embryos development is most easily disturbed during this time

Question 68

teratogenic agents

Answer 68

a chemical, physical, or biologic agent that produces abnormalities during embryonic or fetal development that can cause birth defects

Question 69

teratogenic agents are divided into 3 groups

Answer 69

radiation, chemical and drug substances, infectious agents

Question 70

radiation teratogenic affect on embryonic development

Answer 70

cause microcephaly, skeletal malformations and mental retardation

Question 71

chemicals and drugs teratogenic affect on embryonic development

Answer 71

can cross placenta and damage embryo and fetus

Question 72

examples of environmental teratogenic

Answer 72

organic mercurial which causes neurologic deficits and blindness- certain fish an water sources contaminated by mercury

Question 73

drug teratogenic

Answer 73

thalidomide, chemo agents, anticoagulant coumadin, anticonvulsant meds

Question 74

fetal alcohol syndrome

Answer 74

alcohol passes freely btwn placenta barrier; concentration of alcohol in the fetus is the same as in the mother

Question 75

infectious agents teratogenic

Answer 75

many organisms cross the placenta and enter fetal circulation results in malformations (TORCH)

Question 76

bonus: TORCH

Answer 76

toxoplasmosis, other rubella, cytomegalovirus, herpes