Patterns Of Inheritance I

Question 1

Pleiotrophy

Answer 1

The mutation produces multiple distinct phenotype so that may or may not appear in a particular individual

Question 2

Why are pedigrees useful

Answer 2

Is the trait heritable
Chromo location of cause genes
Risk to other family members

Question 3

Proband

Answer 3

Isolated case of a genetic disorder involving a family member who draws attention to a pedigree

Question 4

Index case

Answer 4

The clinically affected family member through whom attention is first drawn to a pedigree of particular interest to human genetics

Question 5

Penetrance

Answer 5

The probability that a gene will have any phenotypic expression at all

Question 6

Expressivity

Answer 6

The severity of expression of the phenotype

Question 7

Pleiotropy

Answer 7

When an allele of a gene produces several phenotypic effects

Question 8

Autosomal Dominant Inheritance Characteristics

Answer 8

1. Multiple generations affected
2. Males and females are equally affected
3. Male to male transmission
4. Each offspring has a 50/50 chance of being affected to unaffected

Question 9

AD disorders that are homozygous are…

Answer 9

Lethal

Question 10

Examples of AD diseases

Answer 10

Polycystic Kidney Disease
Defect in PKDI on 16p13
Onset when 40-50

Question 11

Autosomal recessive characteristics

Answer 11

Parents can be unaffected

Equal expression in both sexes

Question 12

Examples of AR inheritance diseases

Answer 12

Taysachs disease

Accumulation of gangliosides in neurons

Question 13

PKU

Answer 13

AR disease involving mental retardation and can be averted with proper dietary considerations in a timely fashion

Question 14

Consanguinity

Answer 14

Genetic relationship where individuals have at least one common ancestor in the preceding few generations

Question 15

First Degree Relatives

Answer 15

50% of genes shared

Includes parents, siblings, and offspring

Question 16

Second degree relatives

Answer 16

25% genes shared

Grandparents, aunts/uncles, grandchild, niece/nephew

Question 17

Third degree relatives

Answer 17

12.5 % genes shared

First cousins

Question 18

Isonymous marriage

Answer 18

Marriage between persons with the same surname

Question 19

X-linked recessive inheritance

Answer 19

Much higher incidence in males than females
All daughters if affected males will be carriers
Condition is never transmitted father to son

Question 20

What exceptions cause XR’s to be more severe

Answer 20

Extreme Lyonization

Turner Syndrome

Question 21

Examples of XR inheritance

Answer 21

Hemophilia A and DMD

Question 22

XD inheritance characteristics

Answer 22

Females should be affected twice as much as males

All daughters of affected males will be affected and none of the sons will

Question 23

XD disease examples

Answer 23

Ret Syndrome

Vitamin D resistant rickets

Question 24

Mitochondrial inheritance characteristics

Answer 24

-inheritance has maternal origin
-all offspring of an affected mother are at risk of being affected
All daughters of an affected mother are at risk of transmitting the disease

Question 25

Heteroplasmy

Answer 25

More than one type of mDNA is seen in the mitochondria of an individual

Question 26

Examples of mitochondrial diseases

Answer 26

LHON(bilateral vision loss) KSS(retinal pigment degeneration) MERRF

Question 27

Y linked inheritance

Answer 27

Only males are affected and one male to male transmission is seen