Pedigree Analysis

pedigrees are used to

analyze the human crosses that already exist

pedigree

a family tree used by geneticists to track how a trait is inherited through generations

autosomal trait

appears equally often in males and females

X-linked traits

If males are much more likely to have the trait

If a trait results from an autosomal recessive allele, the individuals with the trait must be

homozygous

If a trait results from an autosomal recessive allele, the parents are

heterozygous carriers

Homozygous

having two identical alleles for a gene.

heterozygous carriers

An individual with one normal allele and one recessive disease allele.

If a trait results from an autosomal dominant, allele, individuals with the trait will be

homozygous or heterozygous

What does this symbol mean

female unaffected

What does this symbol mean?

Female affected

What does this symbol mean?

female carrier of recessive allele

What does this symbol mean?

Male unaffected

What does this symbol mean?

Male affected

What does this symbol mean?

Male carrier of recessive allele

What does this symbol mean?

Mating

Do autosomal recessive traits usually appear in every generation?

No, they often skip generations.

What is a clue that a pedigree shows autosomal recessive inheritance?

Affected children often have unaffected parents.

In Autosomal Recessive Disorder Number of affected males and females is roughly

equal

In Autosomal Recessive Disorder, the children of two affected (homozygous) parents are

affected

example of autosomal recessive disorder

sickle cell anemia and cystic fibrosis

In Autosomal Dominant Disorder, Number of affected males and females is roughly

equal

In Autosomal Dominant Disorder, The trait does not

skip generations

In Autosomal Dominant Disorder, Unaffected parents have only

unaffected children

In Autosomal Dominant Disorder, An affected parent will both

affected and unaffected children

Example of autosomal dominant disorder

Polydactyly