Chapter 7 Flashcards
allele
version of a gene (could be many versions for the same gene), single dominant; 2+= dominant= polymorphic
locus
particular location on a chromosome (could be anything -band -many genes- or 1 gene
Single- gene disorder
- alleles at single locus determine if someone has the disorder or not
- 1 million live births=0.36%
- mendelian= because happen in babies with regular probabilities
How does a variant arise?
- nucleotide sequence has to be different
- mutation (not always bad)
- medical genetics (usually disease= alleles/ changes)
OMIM
- online Mendelian Inheritance in Man
- online database (relationship between genotype and phenotype)
- Mendelian
genotype
collection/specific allele of genotype
phenotype
physical result of the genotype (visual characteristics)
pedigree
-graphical representation of family tree
=shows single-gene disorder inheritance in families
-standard symbols
proband
first affected person (who comes to genetic counsellor and pedigree built around them= IS affected
sibs
siblings
sibship
collection of brothers and sister
First Degree
parents and siblings and children
Second degree
grandparents, parent’s siblings, neices/nephews, grandchildren and half siblings
Third degree
cousins
kindred
entire pedigree= collection of individuals
consultand
maybe affected but also relative of the proband
consaguinity
couples who have 1 or more ancestors in common
Autosomal Recessive
need to be homozygous for a mutant allele to show phenotype
Autosomal Dominant
need at least 1 dominant allele to show the phenotype
Pure dominance
same phenotype regardless of Aa or AA
incomplete dominance
alleles combine to give a mixed phentoype
x^a
x-linked recessive
x^A
x-linked Dominant
Factors that affect a pedigree
- some disorders not experienced at all, even though the genotype affects other members
- phenotype can vary between members of a family