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Polydactyly

Polydactyly. Brachydactyly Human Pedigree Analysis

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Page 1: Polydactyly. Brachydactyly Human Pedigree Analysis

Polydactyly

Page 2: Polydactyly. Brachydactyly Human Pedigree Analysis

Brachydactyly

Page 3: Polydactyly. Brachydactyly Human Pedigree Analysis
Page 4: Polydactyly. Brachydactyly Human Pedigree Analysis

Human Pedigree Analysis

Page 5: Polydactyly. Brachydactyly Human Pedigree Analysis
Page 6: Polydactyly. Brachydactyly Human Pedigree Analysis
Page 7: Polydactyly. Brachydactyly Human Pedigree Analysis

A child that has retinoblastoma

Page 8: Polydactyly. Brachydactyly Human Pedigree Analysis

Manute Bol had Marfan Sydrome

Page 9: Polydactyly. Brachydactyly Human Pedigree Analysis

Michael Phelps has Marfan Sydrome

Page 10: Polydactyly. Brachydactyly Human Pedigree Analysis

Human Pedigree Analysis

Page 11: Polydactyly. Brachydactyly Human Pedigree Analysis

Anatomy of a Pedigree

Male (left) Female (right)

Affected individuals

Carriers (Heterozygotes for autosomal recessive)

Deceased individuals

Sex unspecified

Page 12: Polydactyly. Brachydactyly Human Pedigree Analysis

Anatomy of a Pedigree

Generation

Mating

Adoption

Siblings

Identical twins

Fraternal twins

Consanguineous marriage

Page 13: Polydactyly. Brachydactyly Human Pedigree Analysis

Autosomal dominant (e.g., retinoblastoma)

AAaffected

Aaaffected

Aaaffected

aaunaffected

A a

A

a

Affected parent (Aa) X Affected parent (Aa)

Page 14: Polydactyly. Brachydactyly Human Pedigree Analysis

Autosomal recessive (e.g., PKU)

Aaunaffected

(carrier)No PKU

aaaffected

PKU

Aaunaffected

(carrier)No PKU

aaaffected

PKU

A a

a

a

Unaffected parent (Aa) X Affected parent (aa)

Page 15: Polydactyly. Brachydactyly Human Pedigree Analysis

Autosomal Dominant (e.g., Huntington disease)

Page 16: Polydactyly. Brachydactyly Human Pedigree Analysis

Characteristics of a Dominant Pedigree

• An affected individual has at least one affected parent

• As a result, dominant traits show a vertical pattern of inheritance – the trait shows up every generation

• Two affected individuals may have unaffected children

AA AaAa aa

A a

a

a

A

Page 17: Polydactyly. Brachydactyly Human Pedigree Analysis

Autosomal Recessive (e.g., cystic fibrosis)

Page 18: Polydactyly. Brachydactyly Human Pedigree Analysis

Characteristics of Recessive Pedigrees

• In pedigrees involving rare traits, a horizontal pattern of inheritance is observed– the trait may not appear in every generation

• An individual who is affected may have parents who are not affected, particularly as a result of consagineous matings

• All the children of two affected individuals are affected

aa aaaa aa

a a

a

a

Page 19: Polydactyly. Brachydactyly Human Pedigree Analysis

Pedigree of a family with some members showing the Marfan Syndrome

Page 20: Polydactyly. Brachydactyly Human Pedigree Analysis

Marfan syndrome is

Page 21: Polydactyly. Brachydactyly Human Pedigree Analysis

Marfan syndrome is

Page 22: Polydactyly. Brachydactyly Human Pedigree Analysis

Issues with genetic screening

• Why carry out genetic screening at all?• When is a test accurate and comprehensive enough to be

used as the basis for screening?• Once an accurate test becomes available at reasonable

cost, should screening become required or optional?• If a screening program is established, who should be

tested?• Should private companies and insurance companies have

access to employees and client test results?• What education needs to be provided regarding test

results?