Genetics

Question 1

What inheritance type is incontinentia pigmenti?

Answer 1

X-linked dominant
Boys don’t survive

Question 2

What is the genetic mutation in Prada Willi syndrome?

Answer 2

Deletion of the paternal copy of 15q11-13

Question 3

What is the genetic mutation in Angelman Syndrome?

Answer 3

Deletion of the maternal copy of 15q11-13
UBE3A

Question 4

What condition is related to mutation on 6q?

Answer 4

Neonatal diabetes mellitus

Question 5

What is the genetic mutation in BWS?

Answer 5

Duplication on paternal copy of 11p1-5

Question 6

What is the genetic mutation in Russell silver syndrome?

Answer 6

Duplication on maternal copy of 11p1-5
Can also be UPD on 7q

Question 7

What is associated with a mutation in COL2A1 or COL11A?

Answer 7

Stickler syndrome

Question 8

What are the key characteristics of an autosomal dominant pedigree?

Answer 8

Affected person often has affected parent
Both sexes affected equally
Transmitted by either sex
Risk to child of affected person is 50%

Question 9

What are the characteristics of an autosomal recessive pedigree?

Answer 9

Affected person usually has unaffected parents
Parents of affected person are usually carriers
Increased incidence of parental consanguinity
Affects either sex
25% risk if a prior child is affected

Question 10

What are the characteristics of an X-linked inheritance pedigree?

Answer 10

Affects almost exclusively males
Affected males born to unaffected parents; m other is asymptomatic carrier
Females may be affected if father is affected and mother is carrier or if X inactivation in female is skewed
No male to male transmission

Question 11

What does expressivity mean?

Answer 11

Variability in the expressed phenotype between individuals with a condition

Question 12

What does incomplete penetrance mean?

Answer 12

Even though the mutation might be present the disease phenotype doesn’t always manifest clinically.

Question 12

Allelic heterogeneity vs Locus heterogeneity?

Answer 12

Allelic heterogeneity: many different types of mutations in a gene can result in the same disorder.
Locus heterogeneity: mutations in many different genes can result in the same disorder.

Question 13

What are the characteristics of mitochondrial inheritance?

Answer 13

• Both sexes affected
• Transmission only by females
• Mitochondria are maternally derived
  only
• No transmission by males

Question 14

What can a chromosomal microarrays not detect?

Answer 14

Balanced chromosome configurations/translocations (need karyotype)
Balanced insertions
Inversions