Download Genetic Counseling

Genetic Counseling
Making a Pedigree
By Diana L. Duckworth
Rustburg High School
Campbell County
Pedigree
Female with trait
Male with trait
Normal female
Normal male
Mating (marriage?)
Children, birth order left to right
Example
Now do your own pedigree, showing
those with whom you share genetic
material.
Sex Linked Gene
• The y chromosome has very few genes
• Any gene on the X chromosome is sex linked
• If the phenotype is found predominantly in
males, then it is sex linked
• If recessive, female must be homozygous to
express the gene
• Any male possessing the allele will have the
phenotype
• Example: albinism & hemophelia
Genetic Disease
• Sickle Cell Anemia – abnormal hemoglobin
molecules; 1/500 African Americans; recessive
• Hypercholesterolemia – abnormal receptor for
cholesterol; dominant; 1/500
• Tay-Sachs – defective brain enzyme; recessive;
1/3500 in Ashkenazi Jews (children)
• Cystic Fibrosis – recessive; defective chloride ion
transport protein; 1/2500 Caucasians
• Hemophilia – sex-linked recessive; blood clotting
factor defective; 1/10000
• Huntington’s Disease – inhibitor of brain cell
metabolism; (middle age); dominant; 1/10,000