3.2 Pedigree Analysis

Autosomal dominant traits

• appear equally in males and females

• doesn’t skip generations

• affected children have an affected parent

• unaffected people do not transmit the trait

Autosomal recessive traits

• appear equally in males and females

• skips generations

• more to appear among progeny of related parents

X-linked dominant

• doesn’t skip generations

• affected males pass trait to all daughters and no sons

• affected heterozygous females pass trait to half of sons and half of daughters

X-linked recessive traits

• affected males produce carrier daughters

• no sons of affected males are affected

• males more likely to be affected than females

• half of the sons of an unaffected carrier will be affected

Y linked traits

• traits appear only in males

• all sons of affected males will be affected

Mitochondrial (mtDNA) traits

• affected females pass the trait to all children

• affected males never pass down the trait

Organelle inheritance doesn’t follow Mendelian ratios which leads to…

random segregation of mtDNA during meiosis and mitosis leads to unequal inheritance of mtDNAs