Genetics Flashcards
def: codominance
both alleles contribute to phenotype (blood type)
def: variable expressivity
phenotype varies amoung individuals with same genotype (NF1)
def: incomplete penetrance
not all individuals with mutant genotype show the mutant phenotype (BRCA1 - not everyone gets cancer)
pleiotropy
one gene contributes to multiple phenotypic effects (PKU - lots of different signs/sx)
imprinting
differences in gene espression depending on if the mutation is maternal or paternal (Prader-willi/angelman’s)
anticipation
increased severity, or earlier onset of dx in each generation (huntington’s)
locus heterogenetity
mutations at different loci can produce the same phenotype (marfan’s, MEN2B and homocysturia all cause marfanois habitus)
heteroplasmy
precesnes of normal and mutated MtDNA
hardy-weinberg shows
Psq +2pq + qsq. Psq is the frequency of homozygosity for allele P. Qsq is the frequency of homozygosity for allele Q. 2PQ is the frequency for hetrozygosity
prader-willi imprinting from the
Paternal 15 not expressed)
angelMan;s imprinting from the
Maternal 15 not expressed
MR, hyperphagia, obesity, hypogonadiasm, hypotonia
Prader-Willi
MR seziures, ataxia, inappropraite laughter
Angelman’s
ragged red fibres in muscle biopsy
myopathy of mtDNA inheratance
genetic defect in Achondroplasia
FGF receptor 3 (AD)
genetic defect in AD polycystic kidney dx
PKD1 on 16 (AD)
genetic defect in FAP
APC gene on 5 (AD)
genetic defect in famial hypercholesterolemia
defective/absent LDL receptor (AD)
signs of hereditary hemorrhagic telangiectasia
teleangiectasia, recurrent nosebleeds, skin discolorations, AVMs (AD)
genetic defect in hereditary s[herocytosis
spectrin/ankyrin defect - hemolytic anemia (AD)
treatment for hereditary s[herocytosis
splenectomy
genetic defect in Huntington’s
CAG repetes on 4 (AD)
tumors in MEN
endocrine glands (AD)
genetic defect in NF1
long arm of 17 (AD)
signs of NF1
cafe-au-lair spots, neural tumors, iris harmtomas (AD)
genetic defect in NF2
NF2 on 22 (AD)
sx of NF2
bilateral acoustic schwannomas, juvy cataracts
tuberois sclerosis
facial lesions, ash-leaf spots, eye hamatromas, MR, renal cysts (AD)
genetic defect in con hippel-Lindau
deletion of VHL tumor supressor on 3 (AD)
tumors in von hippel-lindau
brain, retina, bilateral renal cell carcinomas
genetic defect in CF
CFTR gene on 7. commonly deletion of Phe 508 (AR)
common X linked disorders (10)
Bruton's agammt aglobulima Wiskot - aldrich fabry's G6PD defic Ocular albinism Lesch-Nyan Duchene's/Becker's MD Hunter's Hemophilia A/B Ornithine transcarbomoylase def
type of mutation in Duchenne’s MD
frameshift –> deletion of dystrophin gene (X linked)
worst MD
duchenne’s
large testes, jaw and ears
fragile X
genetic defect in fragile X
FMRI gene (X linked)
trinucleotide expansion diseases (4)
Fragile X
friedreich’s ataxia
huntington’s
Myotonic dystrophy
genetic defect of down’s
trisomy 21 mosly meiotic disjunction
signs of down;s
MR, flat facies, epicanthal folds, simian cerase, duodenal atresia, endocardial cushion defect
risks of older down’s pts
early alzheimer’s and ALL
prenatal tests for down’s
low a-fetoprotein
high b-hcg
low estroil
high inhibin A
edwards’s syndrome
severe MR, rocker bottom feet, small jaw, low-se ears, congenital Heart dx
genetic defect in edwards’s disease
trisomy 18
genetic defect in patau’s syndrome
trisomy 13
patau’s syndrome
severe MR, small jaw/ears, cleft lip/palate, holoprocephaly, polydactly, congenitcl heart dx
genetic defect in cr- du chat
microdeletion of chromosome 5 short arm
slight MR, high functioning verbal skills, extreme friendliness, CV problems
williams syndrome
digeorge syndrome genetic defect
microdeletion at 22q11
disdevelopment in digeorge
3rd and 4th branchial pouches
