Key Takeaways

KEY TAKEAWAYS

· There are 22 pairs of autosomal genes and two sex-linked genes in the human chromosome.

· Chromosomal abnormalities lead to missing chromosomes, extra chromosomes, deletions or additions to chromosomes.

· Many chromosome abnormalities are not directly inherited but are caused by defects in meiosis.

· Many chromosomal abnormalities lead to mental retardation; however, Turner syndrome is not one of them.

· Autosomal dominant disorders are passed on in each generation to half of the affected person’s children.

· Autosomal recessive disorders involve a carrier state that is an unaffected person who passes the disease on only if the other parent is also a carrier or has the disease.

· X-linked recessive traits involve a variety of diseases that do not affect girls nearly as much as boys. Girls are often carriers of the disease.