Ch 5: Genetics Flashcards
what are polymorphisms
genetic variations
what is a mutation
permanent change in DNA
what is an inherited (familial) disease
inherited chromosomal abnormality of one or more parents
what is Marfan Syndrome
dominant, inherited defect in the FBN1 gene encoding the extracellular glycoprotein fibrillin-1
prevents TGF-b which causes bone overgrowth
causes skeletal abnormalities, ocular changes (lens dislocation), and cardiovascular lesions (mitral valve prolapse)
what does fibrilin-1 do
glycoprotein that is a major component of microfibrils found in the extracellular matrix and forms elastic fibers
what is Ehlers-Danlos Syndome
dominant disorder that causes mutations in genes that encode for collagen and its modifying enzymes
effects skin (hyperextensible), joints (hyperextensible), bowl (rupture), and large vessels
what is familial hypercholesterolemia (FH)
dominant disorder that impairs hepatic clearance of LDL
leads to increased serum cholesterol levels which causes premature atherosclerosis
cholesterol deposits along tendon sheaths
what is a xanthoma
papule or nodule typically in tendon sheaths due to lipid deposits
under the microscope, cells are light and have a foamy protoplasm (foam cells)
which organelle is the key component of the intracellular digestive system
lysosome
what is Tay-Sachs Disease
recessive disease where there is a mutation on chromosome 15 which causes severe deficiency of hexosaminidase A
GM2 gangliosides (lipids) cannot be catabolized so they build up in the nerve cells
prevalent in Ashkenazic Jews
presents with cherry red spots in retina, motor and mental deterioration, and dementia
leads to a complete vegetative state
what is Sandhoff Disease
recessive deficiency of hexosaminidase B (HEXB) which results in neuronal injury and also affects the liver, pancreas, and kidney
what is Neimann-Pick Disease (type A/B)
recessive disorder where there is a lysosomal accumulation of sphingomyelin due to inherited deficiency in sphingomyelinase
common in Ashkenazi Jews
affected cells (lipid-laden phagocytic foam cells) become enlarged due to distended lysosomes (occurs in spleen, liver, lymph nodes, bone marrow, etc.)
type A: early death in first 3 years of life due to CNS involvement
type B: organomegaly, no CNS involement
what is Neimann-Pick Disease (type C)
most common out of the three types
primary defect in nonenzymatic lipid transport (transport of free cholesterol from lysosomes to cytoplasm)
at birth: hydrops fetalis (severe swelling), hepatitis, and neurologic damage
what is Guacher Disease
most common type of lysosomal storage disorder
recessive disease where there is a mutation in the glucocerebrosidase
this causes glucocerebrosides (lipids in nerve sheaths) to accumulate in macrophages leading to Guacher cells
type 1: affects spleen and bone marrow
type 2+3: affects CNS
high probability of causing Parkinson due to the disease leading to the accumulation of synucleins (brain proteins)
what are Guacher cells
enlarged macrophages due to the presence of distended lysosomes which are filled with glucocerbrosides
start to resemble wrinkled tissue paper
what is Von Gierke Disease (type 1)
mutation in the glucose-6-phophatase when leads to an accumulation of glycogen in the liver
leads to reduction of blood glucose concentrations (hypoglycemia)
what is mcardle disease (type 5)
deficiency or complete absence of the muscle glycogen phosphorylase enzyme
leads to a disregulation of glucose metabolism in muscles
presents with painful muscle cramps, weakness, etc.
what is pompe disease (type 3)
glycogen storage disease where glycogen is not broken down so it accumulates in the skeletal muscle fibers
what is karyotping
the study of chromosomes typically by a cytogenetiscist
define euploid
any exact multiple of the haploid number of chromosomes (23, 46, 69, etc)
define aneuploidy
error occurs in meiosis or mitosis which causes a cell to have a number of chromosomes that is not a multiple of 23
decode 47,XY,+21
male with 47 chromsomes, one extra 21st
define inversion in terms of a mutation
rearrangment where a single chromosome is broken then reincorporated backwards
define translocation
segment of chromosome is transferred to another
what percentage of all conceptions have a chromosomal abnormality
7.5%
what is trisomy 21
down syndrome - most common chromosomal disorder
extra 21st chromosome
presents with: congenital heart disease (atrioventricular septal defect), neuropathic changes (Alzheimers), short A-P diameter, and open operculum (recessed area in brain)
what is trisomy 13
patau syndrome
extra 13th chromosome
presents with: midline facial defects (cleft lip & palate), hypotelorism (wideset eyes), midface hypoplasia (abnormal development), polydactyly, micropthalmia (decreased size of eyeball)
what is trisomy 18
Edwards syndrome
extra 18th chromosome
presents with: low-set ears, upturned nares, micrognathia (recessed lower jaw), overlapping fingers, rockerbottom feet, horseshoe kidney, and valvular dysplasia
what is cri du chat syndrome
cat cry syndrome
partial deletion of short arm of chromosome 5
presents with: round oval face, catlike cry, and growth and mental retardation
what is triploidy
69 chromosomes - not compatible with life
presents with: hydrocephalus, low set ears, hypertelorism (wide set eyes), bulbous nose, sloping forehead, syndactyly (webbed), and camptodactyly (fixed bent position)
what is monosomy X
turner syndome - a female who is missing a X chromosome
presents with: cystic hygroma (lymphatic malformation), webbing of the neck, underdeveloped or absence of ovaries, and contraction of heart vessels
what is klinefelter syndrome
males that have and extra X chromosome for a total of 3 sex chromosomes
presents with: gynecomastia, small penis and testis, long legs, etc.
what is fragile X syndrome and what does it present with
martin-bell syndrome
most common genetic cause of intellectual disabilities in males
piece of the X chromosome breaks off
presents with: pectus excavatum, elongated face, large ears, and intellectual disabilities
how should samples for cytogenetics be taken
using sterile techniques such as sterile saline instead of alcohols
where are the best sources for cytogenetics tissue
fascia, lung, achilles tendon, chorionic villi, and cartilage
