Inheritance and Pedigree Charts Quiz

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