Mosaic Phenotypes

Overview

1) Mosaicism results from the mutation in part of somatic cells after the fertilization, only a few cases occur dueto mutation during meiosis. Mosaicism is characterized by genetic or functional difference of two or more cell linesin one individual from one zygote. 2) Phenotypical variety is high and depends on the proportion of cell lines ofindividual clones. 3) Clinical prognosis of mosaic individuum is better in comparison to the full mutation in all cells.4) The genetic prognosis of reproduction in relatives of the mosaic individuum is without increased recurrent risk,genetic prognosis of own offspring depends on the moment of mutation occurrence – wheit occurs before day 16 to20 when gonadal cells are differentiated, it represents high risk of transmission. 5) Diagnosis of mixoploids in somecases requests investigation of different cells (fibroblasts, lymphocytes). 6) Clinical „signal“ features of the mosaicare hemihypertrophy, asymmetry, Blaschko lines, pigmentations. 7) Risk of malignant tumor is increased, similarlyto other chromosomal aberrations, chromosomal instability or hamartomatoses. 8) Mosaics of gene mutation haveusually normal mental development and are manifested by external abnormalities only. 9) Incidence of mosaicphenotypes is high and therefore the diagnosis of mixoploids and gene mosaic is important for the estimation ofclinical as well as genetic prognosis.

Key words:
mosaicism, cell lines, clinical and genetical prognosis, hemihypertrophy, Blaschko lines, increasedrisk for malignancy.