Transcript Genetic Disorders and Pedigrees

Pedigrees
Pedigrees
 A type of chart that is used to show the patterns of
transmission of a trait within a given family
 Usually produced after an undesirable trait appears
within a family
 Used to figure out the ways that the trait might be
passed along, to counsel parents on the cause of
the disease or in predicting the probability of
parents having an affected child
Pedigree Patterns affected by:
 Whether it is an autosome or X-linked gene
 Whether the trait is dominant or recessive
 The chance of transmission of the gene from the
parents to the children
 Can be confusing if multifactorial traits are
involved
Here is a list of symbols that are commonly
used when making pedigrees:
Autosomal Recessive Inheritance
 Both parents of an
affected individual
must be
heterozygous
 Affected
individuals might
skip generations
 Males and females
are affected in
equally.
Autosomal Dominant Inheritance
 Half the children of an
affected parent are
generally affected.
 The trait is transmitted
only by affected
individuals and does not
skip generations
 Males and females
affected equally.
 Father to son
transmission is possible
X-linked Recessive Inheritance
 No father to son
transmissions
 Father to daughter
carrier is possible
 Female carrier will
transmit to half her
sons
 Males are affected the
most.
 Skips generations
Questions:
 Page 198 Read through sample problems 1 and 2.
 Page 199 Practice problem # 1 and 2
 Page 201 #1-5