Med Genomics 3 Flashcards
autosomal dominant
reoccurence = 50% probability child will get affected or normal
vertical transmission
one dominant allele
seen in each Aa not aa
causation of the same disease phenotype by mutations at different loci
locus heterogeneity
genes that have more than one discernable effect on the body are said to be …
pleiotropic
autosomal recessive
reoccurence = 25%
horizantal transmission
two affected parents will cause 100% affected
consanguinity seen
differential activation of genes depending on the parent from why they are inherited
genomic imprinitng
inactive genes are called imprinted
long arm of chromosome 15 from
the father = prader willi syndrome (fat)
the mother = angelman syndrome (mental)
anticipation and repeat expansion
in pedigree, as generation go on the disease displays an earlier age of onset and or more severe expression in more recent generations but will repeat and expand in further generations
Disease associated with repeat expansion
- fragile x syndrome
- friedfreich ataxia
- huntingtons
fragile x - CGG (utr)
friedrich ataxia - GAA (intron)
huntingtons disease - CAG (exon)
freidreich ataxia
GAA triplet - intron - site of expansion and affected sequence causes by nucleotide repeat mutation - autosomal recessive
Trisomy 21
1 in 800 live births
DOWN SYNDROME
95% of down syndrome is caused by what?
nondisjunction
95% of these are contributed by mother
75% occur during MEIOSIS 1
Trisomy 18
edward syndrome
most common chromosome abnormality among still borns
Trisomy 13
Patau syndrome
clefts, small eyes, polydactylyl
Trisomy 16
most common at conception, never seen in a live birth
Turner syndrome
karyotype 45x
females
short neck and stature
Trisomy XXY
Karyotype 47xxy
Klinefelter syndrome
males
tall stature, long arms and legs
harmful agents that could break chromosomes
clastogens
interchange of genetic material among NONhomologous chromosomes
translocations
reciprocal - two breaks on different chromosomes with exchange of genetic material which result in duplication or deletion
robertsonian - long arms of two chromosomes fuse at centromeres to single chromosome
fragile x syndrome
most common inherited cause of mental retardation - INHERITED - X exhibits breaks and gaps in tips of long arm
down sydnrome is chromosomal abnormality and not inherited gene mutation!
when chromosomes divides perpendicular to its usual axis of division - resulting in chromosome that has two copies of one arm and no copies of the other
the genetic material is substantially altered so most are LETHAL
most isochromosomes observed at live births involve the X – have features of turner syndrome
isochromosomes
trisomy 21 45x 47xxx 47xxy - klinefelter 47xyy
trisomy 21 - 1/800 45x - 1/5,000 47xxx - 1/1,000 47xxy - 1/1,000 47xyy - 1/1,000
