I have some pedigree which is of autosomal dominant disease but I thought there is some other inheritance pattern also?
Autosomal dominant inheritance often manifests together with two other separate phenomena: 1) Variable expressivity and 2) Incomplete Penetrance. The latter, incomplete penetrance is an "all or none" presence or absence of the phenotype in an individual at a particular time. The former, variable expressivity, has do with the many guises of a phenotype as it displays the influence of environment, modifier genes and stochastic processes. Neurofibromatosis type I provides an excellent example of variable expressivity in that it shows neurofibromas, café-au-lair spots, freckling and Lisch nodules (benign growths on the iris). Incomplete penetrance is frequent in autosomal dominant tumor suppressor genes where a 2nd mutation is required to manifest a cancer. In that case, a stochastic process that is sometimes influenced by modifier genes, also, is required for the loss of function prerequisite to tumorigenesis. Because of all these complexities, there is no computer algorithm that substitutes for the astute clinician in making these assessments.
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