Pedigree Analysis Quiz: Inheritance Patterns and Charts

What is the primary purpose of a pedigree chart?

Which of the following is an example of an autosomal dominant trait?

In autosomal recessive inheritance, what is required for the trait to be expressed?

Which of the following is an example of an acquired trait?

What is the relationship between genetics and heredity?

What is the primary difference between autosomal dominant and autosomal recessive inheritance?

What is the principle that states that pairs of alleles are separated when gametes are formed?

Which of the following is an example of a condition caused by an X-linked recessive trait?

What is the pattern of inheritance for Y-linked traits?

What is the term used for genes that are controlled by more than two alleles?

Which of the following is an example of a condition caused by a mitochondrial inheritance pattern?

What is the term used when both alleles contribute to the expressed phenotype?

Inheritance and Pedigree Charts

Inheritance is the passing of traits from parents to offspring
A pedigree chart is a record of an individual's family to study the transmission of a hereditary condition
Goals of pedigree charts: determine the mode of inheritance and probability of an affected offspring

Modes of Inheritance

Autosomal Dominant

A single copy of an allele is sufficient to cause a trait
Examples: Huntington's Disease, Progeria, Marfan Syndrome, Hereditary Hemorrhagic Telangiectasia (HHT), Neurofibromatosis (NF)

Autosomal Recessive

Two recessive alleles result in a trait being expressed
Examples: Albinism, Tay Sachs Disease

Mendelian Principles

Segregation: pairs of alleles are separated when gametes are formed
Independent Assortment: pairs of alleles will be sorted independently of one another when gametes are formed
Principle of Dominance: one allele masks the effect of another allele

Non-Mendelian Genetics

Incomplete Dominance: partial dominance or blending when one allele is not completely dominant over another
Codominance: both alleles contribute to the expressed phenotype
Multiple Alleles: genes that are controlled by more than two alleles

Blood Typing

Blood type is determined by the genotype of an individual
ABO blood types: A, B, AB, O

Sex-linked Traits

X-Linked Recessive

Both males and females can be affected, but the trait is much more common in males
Examples: Colorblindness, Hemophilia, Fabry Disease, Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency, Lesch Nyhan

X-Linked Dominant

Both sexes are affected
Examples: Enamel Hypoplasia, Rickets, Rett Syndrome, Incontinentia Pigmenti, Fragile X Syndrome

Y-Linked

No affected females
Example: Auricular Hypertrichosis

Mitochondrial

Both sexes are affected
Example: Leigh Syndrome

Test your knowledge on inheritance and pedigree charts. Explore the modes of inheritance, determine the probability of affected offspring, and learn about different symbols used in pedigree charts.