Chapter 6- Pedigree, Genetic Testing

female representation in pedigree

circle

male representation in pedigree

square

affected offspring ion pedigree

shaded

unaffected/unhealthy offspring

unshaded

denotes a carrier of a trait in pedigree

halfshaded

connects parents to offspring

vertical line

connects siblings

horizontal line

shows the person who is brought to attention

arrow

slsh through individual

deceased

cosanguineous relationship (related partners)

double mating line

often appears in every generation (affected person usually has an affected parent, males and similarily affected, father to son trasmission can occur)

autosomal dominant

may skip generations; affected child cn have 2 unaffected carrier parents; sexes similarly affected; more common with related parents (25 un, 50 car, 25 non carrier)

autosomal recessive

more males affected, no father to son transmission; affected sons have carrier mothers; affected father passes his x alleles to his daughters

x linked recessive

affected father passes trait to all daughters and no sons; affected heterozygous mother passes it to about 50% of her children of either sex

x linked dominant

only males; affected father passes to all sons (if variant is transmitted)

y linked

affected mother can transmit to all children; affected father does not transmit mitochondrial DNA to children

mitochondrial

similar rates in both sexes

autosomal inheritance

generation skipping and unaffected parents with an affected child

recessive inheritance

stained chromosome sunder a slide to observe chromosomes

karyotype

A fluorescent (hybridization) DNA probe binds a chosen chromosome region to test a targeted deletion, duplication, translocation or chromosome locations

fish

genome wide probe base copy number comparioson; detects many deletions/duplications; usually does not detect balanced rearrangements (CMA)

chromosomal microarray

amplifies a selected DNA segment using primers and DNA poly; a fast targeted analysis; needs sequence information for primer design

PCR

separates DNA/RNA fragments mainly by size (DNA is neg charged)

gel electrophoresis

twins thata rise from 1 fertilized egg and share nearly all inherited DNA

monozygotic

arise from 2 fertilized eggs and share on average about half their segragating genetic variants, like ordinary siblings

dizygotic

both twin have a trait, grater in MZ than DZ similarity supports a genetic contribution, but does not prove a trait is entirely genetic

concordance