Mendelian Genetic Disorders


Mendelian disorders occur in families with a pattern that reflects the inheritance of a single causative gene. Studies of families with conditions such as cystic fibrosis, Huntington disease and fragile X syndrome reveal a variety of inheritance patterns that reflect the nature of the underlying gene and the causative genetic lesion.

Keywords: familial disease; pedigree analysis; autosomal recessive; autosomal dominant; X‐linked

Figure 1.

Pedigree symbols. A subset of symbols commonly used to illustrate a family tree, incorporating clinical details and the nature of specific relationships.

Figure 2.

Inheritance patterns of mendelian disorders: (a) autosomal recessive, (b) autosomal dominant and (c) X‐linked recessive.


Further Reading

Connor M and Ferguson‐Smith M (1997) Essential Medical Genetics, 5th edn. Oxford: Blackwell Science.

Gelehrter TD, Collins FS and Ginsburg D (1998) Principles of Medical Genetics, 2nd edn. Baltimore: Williams and Wilkins.

Kingston HM (1997) ABC of Clinical Genetics, 2nd edn. London: BMJ Publishing.

Mendel Web [].

Online Mendelian Inheritance in Man (OMIM™) (2000) [].

Vogel F and Motulsky AG (1996) Human Genetics: Problems and Approaches, 3rd edn. Berlin: Springer‐Verlag.

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Kennedy, Martin Alexander(Sep 2005) Mendelian Genetic Disorders. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0003934]