Genetic disorders

Question 0

MEN 2A

Answer 0

Gene: mutation of germline RET (neural crest cells)
Inheritance: autosomal Dominant
Phenotype: Adrenal medulla (Pheochromocytoma); Parathyroid tumor: 3rd/4rth pharyngeal pouch; parafolliclar cells (medullary thryoid cancer): derived from neural crest cells; associate with 4th/5th pharyngeal pouch

Question 1

Digeorge syndrome

Answer 1

Gene: 22q11.2 deletion
Inheritance: Autosomal Dominant
phenotype: aberrant development of 3rd and 4th pouches -> T-cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroid development); Associated with cardiac defect (contruncal anomalies)

Question 2

Familial adenomatous polyposis

Answer 2

Gene: mutations on chromosome 5 (APC)
Inheritance: autosomal dominant, 2 hit hypothesis
Phenotype: colon becomes covered with adenomatous polyps after puberty.

Question 3

BRCA1/2

Answer 3

Gene: BRCA1/2 tumor suppressor/DNA repair enzyme

Inheritance: autosomal dominant, 2 hit hypothesis

Phenotype: predisposition to breast or ovarian carcinoma