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.
B.
A pedigree is a chart that traces phenotype
and genotype in a family to determine
whether people carry recessive alleles.
Boxes :males Circles: Females
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
A.
Why can lethal alleles pass from generation to
generation?
What methods can be used to detect and
predict genetic disorders?