Genetics: Hodgepodge

Question 1

Muscular dystrophies

Answer 1

1. Duchenne’s
2. Becker
3. Myotonic type 1

Question 2

Duchenne’s

Answer 2

X linked FRAMESHIFT mutation
–largest gene= increased risk of SPONTANEOUS MUTATION
Weakness begins in pelvis and moves superiorly
Pseudo hypertrophy of calf muscles (fibrofatty replacement of muscle)
Gower maneuver:
DEATH FROM CARDIOMYOPATHY

Question 3

Becker

Answer 3

X linked recessive due to NONFRAMESHIFT INSERTION in dystrophin gene
Less severe than Duchenne’s
Onset early adolescence

Question 4

Myotonic type 1

NOT RECESSIVE DISEASE

Answer 4

AUTO DOM
CTG expansion in DMPK gene
Myotonia, cataracts, testicular atrophy, arrhythmia
“My Tonia, my testicles, my toupee, my ticker”

Question 5

Fragile X syndrome

Answer 5

X linked dominant
Trinucleotide repeat in FMR1 gene
“Xtra large testes, jaw and ears”
Macroorchidism, long face with large jaw, large reverted ears, autism, mitral valve prolapse

Question 6

Trinucleotide repeat expansion diseases

Answer 6

Try hunting for my fried eggs
X girlfriend’s first aid helped ace my test
Fragile X - CGG (large testes–lots of circular things)
Friedrich Ataxia - GAA (ataxia–two a’s)

Hungtingtons - CAG
Myotonic dystrophy - CTG

Question 7

Down Syndrome

Answer 7

Trisomy 21
Fetal US: increased beta HCG 
1. Duodenal atresia
2. Hirshprung's 
3. AV septal defect
4. Alzheimer's 
5. Increased risk of ALL and AML

Question 8

Edwards Syndrome

Answer 8

Trisomy 18 (election age = 18) 
Rocker bottom feet, small jaw
Low set ears, clenched hands with overlapping fingers
Prominent occiput 
Death within 1 years of birth

Question 9

Pautau syndrome

Answer 9

Trisomy 13: Puberty = 13
Severe MR, microcephaly, cleft lip/palate, holoprosencephaly, polydactyly
Death within 1 year of life
MIDLINE DEFECTS! (No cut midline)

Question 10

Robertsonian translocation

Answer 10

Long arms of 2 acrocentric chromosomes fuse at the centromere and the 2 short arms are lost
Unbalanced translocation - Down Syndrome and Patau syndrome

Question 11

Cry du chat syndrome

Answer 11

Congenital micro deletion of short arm of chromosome 5 (46 XX or XY)
Microcephaly, MR, high pitched crying, epics that folds, VSD

Question 12

Williams Syndrome

Answer 12

Deletion of long arm of chromosome 7
“Elfin” facies, MR, hypercalcemia, well developed verbal skills, extreme friendliness with strangers, CV problems
“Serena Williams does look like an elf” a very stocky elf…

Question 13

Cystic Fibrosis

Answer 13

Autosomal recessive 
Defect in CFTR gene on ch: 7
--misfolded protein 
encodes a ATP gated Cl channel -- secretes Cl in lungs and GI tract, reabsorbs Cl 
Abnormally thick mucus
1. Recurrent pulm infections
2. Pancreatic insufficiency
3. Infertility 
--men: absence of vas deferens
--women: abnormally thick cervical mucus

Question 14

22q11 deletion syndromes

Answer 14

CATCH22
Cleft palate
Abnormal facies
Thymic aplasia
Cardiac defects
Hypocalcemia (parathyroid aplasia) 
1. DiGeorge Syndrome: thymic, parathyroid and cardiac defects
2. Velocardiofacial Syndrome: palate, facial, and cardiac defects