Genetics single-gene inheritance

Some genetic conditions are caused by mutations in a single gene. These conditions are usually inherited in one of several straightforward patterns, depending on the gene involved ... 

Genetic maps have been used successfully to find the single gene responsible for rare inherited diseases such as cystic fibrosis and muscular dystrophy. Maps are now being used by scientists to... 

Less commonly, variation is discontinuous when differences in response reveal a discrete proportion, large or small, who respond differently from the rest, e.g. poor drug oxidisers or fast and slow acetylators of isoniazid. Discontinuous variation most commonly occurs when response to a drug is controlled by a single gene. The term genetic polymorphism refers to the existence in a population of two or more discontinuous forms of a species which are subject to simple inheritance. By convention the frequency of each species is 1% or more. 

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