Pedigrees. NGSSS SC.912.L.16.2 Discuss observed inheritance patterns caused by various modes of inheritance, including dominant, recessive, codominant,

Pedigrees

NGSSS

SC.912.L.16.2

Discuss observed inheritance patterns caused by various modes of inheritance, including dominant, recessive, codominant, sex-linked, polygenic and multiple alleles

Genetic conditions caused by a mutation in a single gene follow predictable patterns of inheritance within families

The four types of inheritance patterns:– Autosomal recessive– Autosomal dominant– X-linked recessive– X-linked dominant

PEDIGREE

A pedigree is a tool for studying inheritance in humans (in particular, inherited diseases).

It shows the occurrence and appearance (phenotype) of a particular genetic trait, as it is passed from one generation to the next in a family.

How to Read Pedigrees= = malemale = = femalefemale

= = parentsparents

oror = = individualindividual whowho showsshows thethe traittrait

oror = = heterozygousheterozygous carriercarrier ofofautosomalautosomal traittrait

= = offspringoffspring

11 22 33I, II, III, IV, or VI, II, III, IV, or V = = generationgeneration

More Symbols

Identical Twins

Non-Identical Twins

Deceased Individuals

PATTERNS OF INHERITANCEAutosomal Recessive Trait

Seen when individual has 2 copies of allele (One copy of allele, individual is carrier but does not develop condition)

Males and females affected equally

PATTERNS OF INHERITANCEAutosomal Dominant Trait

Condition expressed in individuals with just one copy of allele

Males and females have equal chance of passing on trait to offspring

PATTERNS OF INHERITANCESex-linked Recessive

Not expressed when one normal allele present

Fully evident in males because they have only one copy of X chromosome

Women rarely affected unless both X chromosomes carry the allele

No father to son transmission, but all daughters will inherit one copy of allele (carrier)

PATTERNS OF INHERITANCESex-linked Dominant

Located on X chromosome

so no father to son

transmission but all

daughters affected

Expressed when only one copy of allele present

Carriers are not possible

Your task…

Determine the pattern of inheritance for…– Cystic Fibrosis– Achondroplasia– Tay-Sachs Disease– Huntington’s Disease

Cystic FibrosisPattern of Inheritance?

AchondroplasiaPattern of Inheritance?

Tay-Sachs DiseasePattern of Inheritance?

Huntington’s DiseasePattern of Inheritance?

HemophiliaMode of Inheritance?