genetics Flashcards
pharmacogenomics
the study of how inherited genetic differences in humans influence individual responses to drugs
polymorphism
genes that have more than one normal allele at the same locus
genotype/phenotype
genetic constitution/expression of genotype
mitosis
2n-2n (diploid)
meiosis
2n-n (haploid)
dominant traits
allele whose effects are observable in either homozygote or heterozygote state
recessive trait
requires homozygote condition of genes to be present
homozygote gene
required for recessive allele to be expressed. both alleles are identical
heterozygote
different allele at each locus of gene. One allele dominant over the other.
hemizygote
a diploid individual with only one allele at a given locus or gene instead of typical two. The men are physiologically hemizygous for the genes located on X chromosome
penetrance
percentage of individuals with a specific genotype who also exhibit the expected phenotype
karyotype
identification of individual chromosomes prepared by slides during metaphase
aneuploid cell
a somatic cell that does not contain a multiple of 23 chromosomes
cri-du-chat syndrome
partial deletion of p arm of chromosome 5
turners syndrome
45, XO deletion of a sex chromosome phenotypical females sterile short stature webbed neck
sex chromosome addition
klinefelters syndrome 47, XXY phenotypical male sterile no body hair gyno tall
trisomy 21/ downs syndrome
47xy+21
mental retardation short
hypotonia
simian crease(line)
familial hypercholesterolemia
chromosome 19
most common mendelian disorders
lack of ldl surface receptor
elevated plasma cholesterol
heterozygote plasma cholesterol in familial hypercholesterolemia
2-3 fold higher than normal
300-400 mg/dl
homozygote plasma cholesterol in familial hypercholesterolemia
5 times higher than normal
600-1200 mg/dl
autosomal recessive genes
inborn errors of metabolism
PKU-phenylketonuria
chromosome 12
accumulation of phenylalanine-cns damage
treatment-diet low in phenylalanine
gene therapy candidate
cystic fibrosis
chromosome 7
exocrine disorder
most lethal single autosomal recessive defect
defect in cftr(cystic fibrosis transmembrane conductance regulator)
gene therapy candidate
x linked defects
hemophilia, color blindness, fragile x syndrome, muscular dystrophy
factors related to developmental defects arise during what period
embryonic period
2-8 weeks after conception
TORCH
toxoplasmosis, other, rubella, cytomegalovirus, herpes
thalidomide
tranquilizer
banned worldwide after 12000 babies born with malformations
reduced tnf alpha- a cytokine
inflammatory response reduced and blood vessel growth arrested
fetal alcohol syndrome signs
craniofacial- small head, chin and upper lip
growth- small, 2 sd below mean
cns abnormalities- microencephaly, hypotonia, retardation
what reduces incidence of ntd by 50-70%
folic acid
cell free fetal dna testing
tests mothers blood for babys dan
can detect several chromosomal defects 98% of time
maternal blood sample/ quad screen test
alpha fetal protein (low=downs)(high=ntd) unconjugated estriol (low=downs) hcg(high=downs) inhibin A (high=downs)
can detect 11-35% chromosomal abnormalities
level 2 ultrasound
amniocentesis
sampling amniotic fluid
15-18th week of pregnancy
what does amniocentesis test show?
cytogenetic disorders
x linked disorders
ntd
inborn errors of metabolism
only in 1st trimester(10th week)
can detect downs
can’t detect ntd
chorionic villi sampling (cvs)
