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Pedigree Analysis meaning, Inheritance Pattern and Problem Solving tips and tricks

What is a Pedigree Chart?

      Definition: Pedigree chart is a diagram that shows the presence or absence of a trait in a family over several generations.

      It is widely used to track genetic diseases or traits over generations

This is a simplified video that will help you to improve your understanding and problem solving skills in pedigree analysis

Common symbols are the following

Pedigree analysis basic symbols

1 Y-Linked Inheritance

Y-Linked Inheritance tips

      Y chromosome passed from father to son.

      Affected men pass the trait to all sons

      Daughters are not affected

      The trait doesn’t skip generations

      Hairy ears, Retinitis Pigmentosa.

2 X-Linked Dominant Traits

More in Females than males

X-Linked Dominant Trait pedigree charcteristics

a) If father is affected

      No male to male transmission

      All daughters of affected father are affected

b) If mother is affected

      Both Daughters & sons are affected (50%)

      The trait doesn’t skip generations

      Fragile X syndrome

3 X-Linked Recessive Disorder

More in males than females

X-Linked Recessive Disorder charcteristics

a) If father is affected

      No male to male transmission

      All daughters becomes carriers

b) If mother is carrier

      ¼ Affected son and carrier daughter

b) If mother is affected

      All sons become affected

      The trait skips one or more  generations

      Hemophilia, Fabry disease

4 Autosomal Dominant Disorder

Autosomal Dominant Disorder pedigree

      Affected children born to affected parent

      Both males and females are affected in equal frequency

      50% children affected from affected parents

      The trait doesn’t skip generations

      Huntington disease, Marfan syndrome, polydactyly, Neurofibromatosis type 1, achondroplasia

5 Autosomal Recessive Disorder


      Affected children born to affected or carrier parent

      Both males and females are affected in equal frequency

      If both parents are carriers (heterozygous), ¼ children gets affected

      The trait often skip generations

      More likely to appear in progeny of related individuals

      cystic fibrosis, sickle cell disease

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