W7 Patterns of Inheritance

Question 1

Neurofibromatosis type I (NFI)

Answer 1

• Autosomal dominant
• Cafe au lait spots
• Tumor disorder

Question 2

Cystic fibrosis

Answer 2

Allelic heterogeneity

Question 3

Rentinitis pigmentosa

Answer 3

locus heterogeneity

Question 4

Hyperphenylalanemia

Answer 4

locus heterogeneity (different enzymes)

Question 5

RET mutations

Answer 5

Phenotypic heterogeneity

Causes either:

Hirschsprung disease (chronic constipation)

or

Multiple endocrine neoplasia types I and II

Question 6

Hemochromotosis

Answer 6

Sex-influences autosomal recessive

(thought is that male behaviors may alter disease phenotype)

Question 7

Tay-Sachs

Answer 7

consagunous disease

higher prevalence in Ashkanazi Jews

Question 8

Achondroplasia

Answer 8

Semidominant

Homozygotes often do not make it to birth

Question 9

Familial hypercholesterolemia

Answer 9

Semidominant

heterozygotes are okay

homozygotes = super expression

Question 10

Male-limited prococious puberty

Answer 10

Sex-limited expression

Question 11

Hemophilia

Answer 11

X-linked recessive trait

Question 12

Mutational mosaicism

Answer 12

mutation in early development

only some genes have mutation and therefore disease

Question 13

Penetrance

Answer 13

whether or not phenotype is expressed

Question 14

Expressivity

Answer 14

degree of phenotype severity

Question 15

Allelic heterogeneity

Answer 15

same disease can result from multiple mutations in one locus

ex: cystic fibrosis

Question 16

Locus heterogeneity

Answer 16

same phenotype results from mutaitons in different loci

Ex: Rentinitis pigmentosa

Question 17

Phenotypic heterogeneity

Answer 17

one mutation causes different disease phenotypes

ex: RET mutations

Question 18

Rett syndrome

Answer 18

X-linked dominant

seen only in females because lethal to males prenatally

(semidominance in females)