# Pedigree and Probability

Topics: Sex linkage, Allele, Zygosity Pages: 2 (472 words) Published: May 5, 2013
What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

What is the mode of inheritance?

Probability: Probability is used to determine the chance of an outcome occurring in any one trial. It is equal to the expected proportion of an outcome in a series of events. Example: Outcome: X-bearing or Y-bearing sperm Events: All sperm in an ejaculate Trial: Fertilization of a single egg Probability: 1/2 for X, 1/2 for Y

• Law of Independence: Applies if the occurrence of an outcome in one trial does not influence the probability of another outcome in a subsequent trial. Example: Given that a couple has had one boy, the probability that their next offspring is male is still 1/2.

• Multiplication Rule: The combined probability of two or more independent outcomes happening in two or more trials is the product of their individual probabilities. [a and b - multiply] Example: The probability of a couple having two boys in row is 1/2 x 1/2 = 1/4. • Addition Rule: The probability of two or more alternative outcomes happening in the same trial is the sum of their individual probabilities. [a or b - add] Example: The probability of a couple having either or boy or a girl is 1/2 + 1/2 = 1.

Waardenburg syndrome is an autosomal dominant condition that accounts for 1.4 percent of congenitally deaf persons. Given that a woman has Waardenburg syndrome (and is assumed to be a heterozygote) and a man is unaffected, what is the probability that none of their three children will be affected?

An unrelated man and woman both have a sibling affected with cystic fibrosis. The man and woman are phenotypically normal. Their parents are unaffected with CF, but are...