What is Genetic Disease and how does it pass from parent to child? Modes of Inharitance

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My dear patient thank you for this question. As those that know this is a complex question - I will try to explain this in the simplest possible way?

Monogenic Inheritance - Mendel 1866: A dominant characteristic is expressed in at least one parent is expressed in half of the offspring.

Recessive characteristic - is evident in a quarter of the siblings born to parents who are both hetrozygous - and do not themselves express the characteristics.

X-Linked Recessive Trait: The female carriers of the X-Chromosome are unaffected due to the presence of a second normal X Chromosome (Females have 2 X chromosomes), while the male offspring inherit the abnormal gene and suffer the disease because males do not have the relevant normal gene on the Y Chromosome (Males are XY). This genetic transmission is seen in the genetic transmission of hemophillia. 


Polygenic Inheritance - is much more difficult to work out. 

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