Answer:
Patau syndrome is caused by having cell in the body that has three copies of chromosome 13 instead of the usual two.
Edwards syndrome is caused by having a third copy of all or part of chromosome 18.
Trisomy X syndrome is caused by a malformation in egg or sperm formation.
Explanation:
The phenomenon where one has three members of a homologous chromosome is called trisomy. Such children are mentally deficient, have a slit eyed appearance and have low chances of surviving because of reduced resistance to infections.
When nondisjunction involves all chromosomes, the resulting gametes are diploid. Patau, Edward and Trisomy X syndromes are examples gene mutations caused by nondisjunction.
