Genetic disorders can be due to any of the following factors: A. Monogenetic Disorders: Caused by a mutation in a single gene 1. Autosomal recessive alleles: a. You may be a carrier and not know it, since the dominant allele masks the recessive. b. Lethal alleles are passed in these heterozygous carriers. Ex: Cystic fibrosis

2. Autosomal dominant alleles: Person would only need one copy of the dominant allele to have the disease. ex: Huntington’s disease 3. Sex linked genes: males only need one recessive allele to have a disorder found on a sex chromosome. Ex: hemophilia

Occur when there are not 2 of each chromosome. 1. Trisomy: When there is an extra copy of a chromosome. 2. Deletions 3. Translocations

C. Multifactoral Inheritance Disorders: caused by a combination of inherited genes and environmental factors. Ex: heart disease, diabetes, and most cancers.

A. Genetic counselors are health care professionals who determine your risk of developing a disorder, or your risk of having children with a disorder.

A. A pedigree is a chart that traces phenotype and genotype in a family to determine whether people carry recessive alleles. B. Boxes :males Circles: Females

A. Gene tests: test for a specific mutation in a DNA sequence. B. Chromosomal tests: include karyotypes, which look for extra or missing copies of a chromosome. C. Prenatal Testing: detects disorders before birth

Why can lethal alleles pass from generation to generation? What methods can be used to detect and predict genetic disorders?