5. Principles of Genetic Inheritance

Question 1

Define “Lyonization”

Answer 1

The random choice of which X chromosome will be activated.

More commonly called X-Inactivation

Question 2

What is the genotype for a patient with Turner Syndrome?

What are the basic symptoms?

Answer 2

45,XO (Absent Y, so femaie)

• Short stature
• Many do not undergo puberty without HRT
• Ovarian hypofunction
• Webbed neck
• CV defects

Question 3

What is the genotype for a patient with Klinefelter Syndrome?

What are the primary symptoms?

Answer 3

47,XXY

Gynecomastia

Tall stature

Infertility

Low muscle mass

Question 4

NEED CARD FOR DOWNS

Question 5

If someone expresses a gene from there father, how is the corresponding gene on the mother’s allele silenced?

Answer 5

Methylation - Called Genomic Imprinting

Question 6

Prader-Willi and Angelman syndromes are both due to the same deletion on Chromosome 15. What determines which disease a patient gets?

Answer 6

It depends on which gene is expressed.

Paternal Chromosome 15 deletion is Prader-Willi

P is for Paternal and Prader-Willi

Maternal Chromosome 15 deletion is Angelman

Mommy’s little angel

Question 7

Define pleiotropy

Answer 7

Individuals with the same genotype having different phenotypes.

Question 8

Define Proband

Answer 8

The first person in a pedigree to have a disease / trait.