Patterns of Autosomal Mendelian inheritance

Question 1

Dysmorphology

Answer 1

the study of birth defects

Question 2

Achondroplasia

Answer 2

Dominant disorder

Question 3

neurofibromatosis type 1

Answer 3

Autosomal dominant disorder (1/3000).
Caused by mutation in NF1 gene (which controls Ras->uncontrolled growth)
Cafe-au-lait spots, freckling, neurofibromas (bunch of skin cancer).
Penetrance is basically 100%, and diagnosis is clear by age 6
Expressivity highly variable
De novo account for half of all cases
Genetic testing not done usually

Question 4

Marfan

Answer 4

Autosomal dominant disorder. (1/7000-10,000)
Mutation in the FBN1 gene which codes for a fibrillin protein.
Highly penetrant
Phenotypes include, skeletal changes (tall stature), ectopia lentis, dilated aortic root.
25% are de novo mutations.
Sometimes there is mosaicism.
With no family history, need systemic feature score

Question 5

cystic fibrosis

Answer 5

recessive

Question 6

PKU

Answer 6

recessive

Question 7

Familial hypercholesterolemia

Answer 7

Dominant disorder