Patterns of Single Gene Inheritance

Question 1

Compound heterozygous

Answer 1

both alleles are mutant, but mutant in different locations on gene

Question 2

Hemizygous

Answer 2

Abnormal gene is located on x chromosome

Question 3

allelic heterogeneity

Answer 3

different mutations occurring on same gene

Question 4

Phenotypic heterogeniety

Answer 4

Different mutations in same gene producing different phenotypes

Question 5

Locus heterogeneity

Answer 5

Mutations at different loci that produce same phenotype

Question 6

Long QT syndrome

Answer 6

phenotype caused my mutations in more than one gene-all have same

locus heterogeniety

Question 7

4 factors that confound pedigree interpretation

Answer 7

early lethality in disorder

small family size

variable age of onset, decreased penetrance or variable expressivity

non-mendelian inheritance

Question 8

Auto rec features

Answer 8

must have 2 mutant alleles and no wild type
-can have different try of mutation in each allele-compound heterozygote

Reduce/eliminate function of gene product
Affect function of enzymes usually

Rare

Question 9

Carrier frequency

Answer 9

Prevalence of disease in given population

Question 10

4 factors that affect risk of inheritance of auto rec disorder

Answer 10

Carrier frequency

Consantuinity-close or closer than second cousins
-increase chance that both parents are carriers of the same mutant allele

Inbreeding

Genetic isolates

Question 11

Key features of AR pedgree

Answer 11

parents are unaffected carriers

males=females

usually recurrence of risk to unborn is 1/4

phenotype found in siblings

Question 12

oblligate heterozygote

Answer 12

person who you are sure is a carrier

Question 13

Auto dom inheritance features (AD)

Answer 13

Every affected individual has affected parent (if completely penetrant)

Male to male transmission

Males and females equally infected

1/2 of offspring have risk

Normal siblings have all normal offspring

Question 14

Incomplete dominance

Answer 14

Individual is homozygous for AD mutation is more severely affected then individual who is heterozygous

Question 15

X linked inheritance

Answer 15

No male to male transmission

X link inactivation results in very different clinical presentations for females
-unbalanced inactivation can result in carrier woman with phenotype

Many more affected males than females

Heterozygous females are usually unaffected

Gene is transmitted from affected male to all daughters

Hidden passage through series of carrier females

Question 16

x linked dominane

Answer 16

trait NEVER passed from father to son

Many more females than males

Question 17

Reduced penetrance

Answer 17

all or none

Probability that mutant gene will have any phenotype at all

Question 18

Variable expressiity

Answer 18

sevirty varies with same exact genotype

Question 19

Sex limited traits

Answer 19

Genes can be carried by opposite sex but an not display because anatomical/physiological difference

Question 20

Hemochromatosis

Answer 20

Most common single gene inherited disease in US

Question 21

Sex influenced pheotype

Answer 21

hemochromatosis

more common in male or female because reason (menstruation lowers iron levels)

Question 22

Mosaicism

Answer 22

Presence of at least two cell lines that differ genetically from single zygote

Question 23

Pure somatic vs pure germline mosaicism

Answer 23

Present in soem tissues in the embryo but not germ cells

Depends on whether the mutation occurred before or after the separation of gremlin cells from somatic cells

Parents are normal, not carrier, and more than one child affected with AD or XLR disorder

Question 24

New mutations

Answer 24

Very low probability per gamete

Affected child will share allies for all other genes with parents

Can result in genetic lethal

Very rare in AR-need to mutate both alleles

Question 25

Genomic imprinting

Answer 25

Sex of transmitting parents plays role in expression of phenotype

100 human genes that only one copy can be active

Question 26

Parent of origen

Answer 26

Specific pattern is present in all somatic cells, but reversed in germ cells

Question 27

Prader willi syndrome
vs
angleman

Answer 27

Loss of fathers chromosome part

Loss of mothers chromosome part

Question 28

TNR disorder principlas

Answer 28

Molecular characteristics and consequences of expansion differ

Tendency for repeat expansion depends on transmitting parent

premutaitons

Genetic anticipation

Question 29

premutation phenotype

Answer 29

can be mildly to affected or even normal

Question 30

genetic anticipation

Answer 30

More TNRs more early and more severe disease is

Question 31

Male limited precocious puberty

Answer 31

Mutation in lut hormone gene

Always on

ONLY IN BOYS

Heteromales-secondary sex char early

Question 32

Parents pass methylation to kids

Answer 32

NO WHAT THE FUCK- REVERSED IN GAMETES