Genetic Disorders

What are they? A disease that is caused by an abnormality in a person’s DNA.

Types of Disorders Single Gene Disorders Chromosomal Abnormalities A mutations causes the protein product to be altered or missing Chromosomal Abnormalities Entire chromosomes, or large segments of them are missing, duplicated, or altered. Multi-factorial Disorders Result from mutations in multiple genes coupled with environmental causes

Single Gene Disorders Cystic Fibrosis Recessive disorder Usually helps move salt into & out of the cell When defective it causes a thick, sticky mucous to be made Causes issues with digestive system & lungs

Single Gene Disorder Sickle Cell Anemia Recessive gene Causes red blood cells to be rigid & concave They are not able to transport oxygen very well (hemoglobin) Resistant to malaria

Single Gene Disorder Huntington’s Disease Dominant disease Causes brain cells to be destroyed that deal with movement, emotion, & thinking

Single Gene Disorder PKU Phenylketonuria (recessive) Codes for an enzyme in the liver that breaks down the amino acid phenylalanine Causes phenylalanine to build up in the blood which poisons brain cells (neurons) Can’t eat protein!

Chromosome Abnormalities Non-Disjunction Disorders When homologous chromosomes or chromatids do not separate during meiosis Results in Monosomy – only one copy of a chromosome Trisomy – having 3 copies of a chromosome

Turner’s Syndrome Only affect females X (missing X) Female appearance Infertile Don’t mature

Klinefelter’s Syndrome Only affects males XXY (extra X) Some female characteristics Very little facial hair Infertile (don’t produce sperm)

Down Syndrome Trisomy of chromosome 21 Causes too much protein to be made, which causes problems

Sex-linked or X-linked Traits More genes can be carried on the X chromosome than the Y Genes ONLY on X chromosomes are called “X-linked” Since there is only one allele, the phenotype of that allele is expressed in males

Examples