A child has a severe intellectual
disability, developmental delay, autism, and unusual facial
features, His mother had a learning disability and slightly delayed
development. Genome sequencing, as well as karyotyping, reveal that
the child has excess material from chromosome 9 and 14 and too
little from chromosome 10. Th mother has all of the genetic
material, but she has four “derivative” chromosomes – they have
seemingly mixed and matched their parts. These chromosomes consist
of pieces of 9, 10, and...