HUMAN PEDIGREE ANALYSIS

HUMAN PEDIGREE ANALYSIS

Pedigrees show the genetic history of a family in what is similar to a "genetic family tree". It shows the phenotypes of a particular genetic trait from one generation to the next in a family. Most of the time the genotypes of the individuals may be determined as well by using your understanding of inheritance.

Can be useful in determining who is a carrier (heterozygote) for a genetic disease, such as:

Autosomal recessive disorders:

Albinism: inability to produce melanin

Tay Sach's: cannot dispose of fatty molecules in nervous system, build up leads to mental degeneration and death

Cystic Fibrosis: recessive disorder on chromosome 7 causes build up of heavy mucous in lungs

Sickle-Celled Anemia: abnormal hemoglobin alters RBC shape and lowers the oxygen carrying capacity of blood

Autosomal Dominant Disorders:

Huntington's Disease: adults lose muscle control, convulsions, nervous degeneration causes death, found on chromosome 4, thus Hh or HH will get the disease

Polydactyly: dominant disorder that causes extra fingers and toes

Each generation is represented by a Roman Numeral, and each person in a generation is labeled with a number in the order in which they were born.

Squares are males and circles are females.

Usually a shaded or darkened symbol shows the condition that is being studied.

All un-shaded symbols are individuals who have the dominant phenotype and at least on dominant allele. Carriers may be identified by symbols with lines through them.

TAY SACH'S DISEASE

SICKLE-CELL ANEMIA