Deletions and Duplications

Deletions and duplications are important structural
aberrations of chromosomes. Deletion,
which causes hemizygosity and functional haploinsufficiency
for the loci involved,may occur
de novo or be the result of the meiotic segregation
of a parental balanced reciprocal translocation
(see p. 198). Duplication of a chromosomal
segment leads to partial trisomy, resulting in
functional imbalance of the genes contained in
the involved region.