Two Types of Mutations Gene mutation: single gene defective

Insertion Substitution Deletion

Chromosomal mutation: missing or extra chromosome Monosomy Trisomy Deletion

Either can involve autosomes (chromosomes 1-22) or sex chromosomes

Autosomal Disorders

Disorders involving the 22 pairs of chromosomes that are NOT sex chromosomes (X,Y).

Can result from Gene mutation: defective gene

on autosome Chromosomal mutation: loss

or gain of autosome

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Autosomal DisordersGene Mutations

1- Cystic Fibrosis Recessive disorder Mutated gene on

chromosome 17. Characterized by excessive,

THICK secretion of the mucus in the body.

Autosomal DisordersGene Mutations

2- Huntington Disease Dominant disorder Mutated gene on

chromosome 4 is responsible.

Causes degeneration of neurons producing dementia, and random jerking movements.

Autosomal DisordersGene Mutations

3- Phenylketonuria (PKU) Recessive disorder Mutated gene on chromosome

12 is responsible4- Sickle-Cell Anemia 1 of 12 U.S. African Americans Recessive disorder Mutated gene on chromosome

11

Autosomal DisordersGene Mutations

5- Tay-sachs Disease Recessive disorder European Jewish ancestry. Mutated gene on

chromosome 15 Tay-sachs—One Wrong Letter

Autosomal DisordersChromosomal Mutations

Down Syndrome 1 in 1,000 live births. Extra Chromosome 21 Risk increases with

mom’s age Pregnancies of women

over age 35 accounts for20% of Down syndrome

births

Sex-Linked Disorders Involve the sex chromosomes Recessive gene on the X chromosome is more

likely to be expressed in males ***Y chromosome has no 2nd allele that might

counteract the gene on the X chromosome!

Sex-Linked DisordersGene Mutations

1- Color Blindness X-linked recessive disorder Gene mutation on X

chromosome 1 of 10 males

2- Hemophilia X-linked recessive disorder Gene mutation on X

chromosome. 1 of 5,000 males Interfere with normal blood

clotting

Sex-Linked DisordersChromosomal Mutations

1- Klinefelter Syndrome (XXY) 1 of 1,000 males. Extra X chromosome

Sex-linked DisordersChromosomal Mutations

2- Turner’s Syndrome (XO) 1 of 10,000 females One of X chromosomes is either

missing or inactive Have immature female appearance

and lack internal reproductive organs.

GENETIC DISORDERS

Autosomal DisordersChromosomes 1-22

Sex-Linked DisordersSex Chromosomes X and Y

Gene Mutations1 gene mutated

on chromosomes 1-22

ChromosomalMutations

Extra or missing chromosome 1-22

Gene Mutations1 gene mutated

on X chromosome

ChromosomalMutations

Extra or missing Sex chromosome

EXAMPLES?

How Do We Know About All of Our Genes?

Human Genome Project Began in 1990

Goals: Determine complete sequence of the

3 billion DNA bases in human DNA Identify all human genes for further

biological study

The Unknown

Gene number, exact locations and functions

Gene regulation DNA sequence organization Chromosomal structure and

organization

Ethical, Legal and Social Issues

Fears Genetic information used to harm or

discriminate Deny access to health insurance Deny employment Deny education Deny loans?

DNA Databases