Genetic Disorders

What are they? A disease that is caused by a recessive allele in a person’s DNA

Types of Disorders Single Gene Disorders Chromosomal Abnormalities A mutation causes the protein product to be altered or missing Chromosomal Abnormalities Entire chromosomes, or large segments of them are missing, duplicated, or altered.

Cystic Fibrosis Recessive disorder Causes a thick, sticky mucous to be made Causes issues with digestive system & lungs

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

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)

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

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

Sex-linked or X-linked Traits More genes are carried on the X chromosome than on 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