Pedigree Analysis, Applications And Genetic Testing Flashcards
What is a pedigree?
A pictorial representation of a family history. It outlines the inheritance of one or more characteristics.
What is a proband?
The person from whom the pedigree is initiated.
What are features of autosomal recessive traits?
They normally appear with equal frequency in both sexes and seem to skip generations.
Examples are cystic fibrosis, sickle cell anemia and Tay Sachs disease.
What are features of autosomal dominant traits?
They appear qually in males in females and are usually present in each generations. Unaffected persons do not transmit the trait, and affected perons whave at least one affected parent.
An example is familial hypercholesterolemia.
What are features of X-linked recessive traits?
They appear more often in males than in females and are not passed from father to son.
A recessive allele is masked in a femal with 2 x chromosomes.
What is an example of an X linked recessive condition?
Duchenne muscular dystrophy.
It includes progressive muscle weakness.
Classic hemophilia is inherited as what type of trait?
X-linked recessive.
X-linked hypophosphatemia is inherited how?
It is an X-linked dominant disorder.
What is a feature of Y linked traits?
They only appear in males and are passed from a father to all sons.
Autosomal recessive traits often appear in bedigrees in which there have been consanguine mating, because these traits:
Appear only when both parents carry a copy of the gene for the trait, which is more likely when the parents are related.
How could you distinguish between an autosomal recessive trait with higher penetrance in males and an X-linked recessive trait?
X-linked recessive traits are only passed to sons from mothers, not from fathers.
What type of twins are dizygotic twins?
Nonidentical twins
What type of twins are monozygotic twins?
Identical twins
What is a a concordant trait?
A trait shared by both members of a twin pair.
What is concordance?
The percentage of twin pairs that are concordant for a trait.
