Introduction to med gen Flashcards
phenotype definition
the physical description of a character in an individual organism
genotype definition
the genes an individual has at a particular site or locus, responsible for the observed phenotype
penetrance definition
the chance that a given genotype will cause a particular phenotype, usually referring to the mutation
character definition
a structure, function or attribute determined by a gene of group of genes
trait definition
alternate forms of a character
locus definition
a location within the genome
consanguineous definition and appearance on pedigree
related couples that form offspring, double line
different twin types and their appearance on a pedigree
monozygotic, identical twins- line between them forming a triangle
dizygotic, fraternal twins- triangle with no bottom line
pregnancy appearance on pedigree
small triangle
name the 6 main modes of inheritance
autosomal dominant, autosomal recessive, X-linked recessive, X-linked dominant, mitochondrial, uni parental disomy
explain autosomal dominant
gene carried on the autosome and affects heterozygotes
3 examples of autosomal dominant conditions
Huntington’s disease, breast cancer, Marfan syndrome
explain autosomal recessive
gene carried on the autosome and only affects homozygotes with 2 copies of the mutated gene. Two carriers of the condition would result in a 25% chance of offspring having the condition
3 examples of autosomal recessive conditions
cystic fibrosis, sickle cell anaemia, albinism
explain X-linked recessive
in a woman, both Xs would need to carry the mutation to be affected, in the man only the X needs to be affected. Female carriers are usually unaffected due to X-linked inactivation
3 examples of x-linked recessive conditions
haemophilia, colour blindness, Duchenne muscular dystrophy
explain X linked dominant
if woman inherits one mutant X they will be affected but due to X-inactivation they will survive, men will die.
