germinal mutation

With a germinal mutation, all cells are predisposed.
The tumor arises after loss of function
of the second allele. When somatic mutation
occurs in a single cell, loss of function of both
alleles rarely affects the same cell. But with a
germ cells mutation, loss of function of the second
allele is frequent, since all cells carry the
first mutation, i.e., are predisposed. With somatic
mutation, the tumor occurs sporadically
(is not hereditary) and arises unifocally from a
single cell. In the hereditary form resulting from
a germ cell mutation, several tumors may arise
from different cells (multifocal tumor). The predisposition
for the tumor in the hereditary form
shows autosomal dominant inheritance.