Genetic Func

Question 1

Polyploidy

Answer 1

• cells with complete set of extra chromosomes (often seen in plants)

Question 2

• cells with normal number of chromosomes

Answer 2

Euploid

Question 3

• cells contain a missing chromosome or additional individual chromosomes
• Likely due to nondisjunction
• Cause of Down Syndrome, Edwards, and Patau

Answer 3

Aneuploidy

Question 4

• Improper separation of homologs during meiosis I or II
• Major cause of mitotic errors
• Increases with maternal age. As mother’s get older, there is more opportunity for mother’s somatic cells to be mutated.

Answer 4

Nondisjunction

Question 5

• UPD is a phenomenon when individual receives two copies of chromosome or part of a copy from one parent and no copy from the other
• Often asymptomatic as pt. still has one copy of each gene
• Prader-Willi syndrome occurs from this, leads to uncontrolled eating, obesity

Answer 5

Uniparental Disomy

Question 6

• Normal process
• One copy of gene is silenced due to parental origin
• Epigenetic process that involves methylation/histone modification of 5’ end of gene on egg/sperm during their formation (Note: genetic sequence unchanged)
• Certain genes only expressed from father or mother
• Imprinted alleles are silenced such that the gene is expressed only from non-imprinted allele
• Erased in germ cells at each generation

Answer 6

Genetic Imprinting

Question 7

Robertsonian Translocation

Answer 7

13, 14, 15, 21, 22)
• Exchange of material between two chromosomes.
• 13 and 21 cause Patau and Down’s respectively.

Question 8

What syndrome is caused by a deletion is on the paternal chromosome (15)

Answer 8

Prader Willi

i. Short, hypotonia, small hands and feet, fat, mild-moderate intellect disability, uncontrolled eating
- Think of a small willi-cauli stein at 15 yrs…short, w/ small hands (opposite of now)`

Question 9

47, XXY syndrome

Answer 9

Kleinfelters
Small, undescended testes, breast development gynecomastia, infertility, cognitive, social, behavioral, and learning difficulties, tall
-more X’s increase symptoms
-Klein is a real ladies man

Question 10

Trisomy 13

Answer 10

Patau Syndrome 47, xx+13
Most die before birth, 13% survive to 10 y.o. Clenched fist, polydactyl, Heart, kidney, CNS dysfunction. Microencephaly, malformed ears, close/absent eyes, cleft palate
-Gollum Platau’d at age of 13

Question 11

Trisomy 18

Answer 11

Edwards Syndrome 47, XX+18
Often IUGR (in utero growth restriction), less than 10% of births survive >1 year, microencephaly, malformed, low-set ears, small mouth and jaw, cleft palate, rocker bottom feet, overlapped fingers
-Edward Scissorhands had 18 oddly bent fingers and legs with a strange head

Question 12

Trisomy 21

Answer 12

Downs syndrome 47, XX+21
Cardiac defects, duodenal atresia (blocking intestines), cognitive impairment (varies), increased nuchal translucency, short limbs, flattened nose/face, upward slanting eyes
-associated with maternal age

Question 13

45, XO missing chromosome (no Y)

Answer 13

Turner syndrome

-Short, ovarian failure, do not undergo puberty, webbed neck, low hairline, NO cognitive deficits

Question 14

Might cause generational skips on a pedigree, like in retinoblastoma

Answer 14

Incomplete penetrance

Question 15

A single disorder caused by genes in different chromosomal loci

Answer 15

Locus Heterogeneity

Osteogenesis Imperfecta Syndrome

Question 16

Blue sclera, Brittle Bone disease, collagen

Syndrome

Answer 16

Osteogenesis Imperfecta

Question 17

Mosaicism

Answer 17

-two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg

Question 18

Cousins are more likely to produce rare autosomal recessive disorders

Answer 18

Consanguinity

Question 19

Heteroplasmy

Answer 19

• Because each cell contains a population of mtDNA molecules, a single cell can harbor some molecules that have an mtDNA mutation and other molecules that do not. This heterogeneity in DNA composition, termed heteroplasmy, is an important cause of variable expression in mitochondrial diseases.
  Mito must undergo many divisions before sufficient amount to cause symptoms, so deveops later in adulthood