Midterm 2 Flashcards by Amanda Holan

is paternal or maternal nondisjunction more common?

maternal

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deletion of mother’s 15q11-q13 causes what in the child?

Anglemans syndrome (AS)

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paternal deletion of 15q11-q13 causes?

prader willi syndrome (PWS)

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what are the 3 mechanisms that promote imprinting?

hypermethylation of imprinted alleles
deacetylation of histones
chromatin condensation

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cru de chat is an

autosomal deletion syndrome, terminal or interstitial deletion of 5p

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how often do idiopathic chrom abnormalities occur?

1/7,000 live births

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what disorder can occur from a deletion in 22q11.2

DiGeorge or 22q11.2 deletion syndrome

craniofacial abnormalities, intellectual disabilities, HEART DEFECTS IF TBX1 (PROXIMAL) IS DELETED

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22q11.2 duplication can cause

22q11.1 duplication syndrome

no intellectual disability
can cause cat eye syndrome is there’s 3 chroms and one has a reciprocal duplication

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what disorder is 47,XX,+inv dup(22)(pter–>q11.2)

cat eye syndrome

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AZF genes are located?

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which Y-linked genes are needed for sex determination? for spermatogenesis?

SRY/TDF for determination

AZF for spermatogenesis

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each hemoglobin unit contains:

4 heme units
2 alpha
2 Beta

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sickle cell

autosomal recessive disorder of hemoglobin where β subunit genes have a missense mutation that substitutes Valine for Glutamic acid at amino acid 6.

The Glu6Val mut in β-globin decreases the solubility of deoxygenated hemoglobin and causes it to form a sickle shape

DEFECTIVE B CHAINS

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irreversibly sickled cells that are removed from the circulation by the spleen

hemolytic anemia

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T or F, red blood cells have a nucleus

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how many genes are responsible for only one phenotype?

3, 329

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What are the 4 diff effects on protein functions caused by mutations (leading to disease)

loss of function
gain of function
gain of NOVEL property (sickle cell)
misexpression (heterochronic or ectopic)

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based on expression pattern, what are the 2 classes of proteins?

housekeeping and tissue-specific specialty

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single phenotype or a genetic disorder is caused by mutations in one of a multiple number of alleles or loci

genetic heterogeneity

mutation of a single gene leads to multiple phenotypes or genetic disorders

genetic pleiotropy

multiple alleles at a single locus

allelic heterogeneity

PKU can be caused by?

LOF mutation resulting in a deficiency of either PAH or BH4

causes elevated levels of phe in blood

a read-through mutation in FGFR3 causes?

thanataphoric dysplasia

most sequenced pop in the world?

northern europeans

most introns end in (splice acceptor)?

polypyrimidine track then AG

most EXONS end in?

2 purines (AG)

introns start with? this is the splice donor or acceptor?

GT (becomes GU in mRNA) this is the splice donor

what does c.7delC, p.Gln3AsnfsTer8 mean??

the 7th nucleotide C was deleted the 3rd amino acid Gln is now Asn due to a frameshift mut there a premature stop 8 codons downstream of the frameshift

germline vs somatic changes?

Germline mutations are changes to your DNA that you inherit from the egg and sperm cells during conception and affect (usually) all cells in ur body Somatic mutations are changes to your DNA that happen after conception to cells other than the egg and sperm, only affect certain tissues (ex: Proteus syndrome)

what disease only expands its repeats in paternal lineages?

huntington's disease

in Fragile X syndrome, the repeats will get expanded through the ____ lineage?

maternal lineage

what disease has the highest de novo rate in the human genome?

Duchenne muscular dystrophy - exon duplication or deletion

which disease is Gower maneuver associated with?

Duchenne's muscular dystrophy

T or F: dynamic repeats follow typical Mendelian patterns of inheritance

FALSE

CF is a LOF or GOF?

LOF

lactose tolerance is a ?

misexpression

what is the heterozygote advantage of sickle cell anemia?

increased defense against malaria if het (carrier)

what is an example of a dominant negative mut? is this an LOF or GOF?

osteogenesis imperfecta, GOF

hereditary persistence of fetal hemoglobin is?

a heterochronic expression (missexpression)

the gene causing Holoprosencephaly is

haploinsufficient

An extra copy of the PMP22 gene causes? this is a problem of?

causes Charcot-Marie-Tooth disease and is a gene dosage problem

variants that reduce activity or inactivate a protein:

LOF, haploinsufficiency, dominant negative (a GOF)

variants that enhance function, give new functions or expression domains:

heterochronic/ectopic, GOF, novel property gain

if two parent's offspring have 50/50 ratio of recombinant and parental markers are the markers linked or unlinked in the parents?

unlinked

what is the recomb rate (%) if two markers are 3 cM apart?

lets say we are looking at genes with 2 markers and a disease (D) is located btw the markers. the distance from either marker to D is 0.05 cM. what are the odds of a marker-to-marker recombination?

add up both distances (as 2 genes will be crossing over at diff segments - theta 1 and theta 2) = 0.05 + 0.05 = 0.1 --> 10%