Important Genetic Disorders Bio Definitions Autosomes any chromosome

Important Genetic Disorders Bio

Definitions • Autosomes- any chromosome that is not a sex chromosome. Not the “X” or “Y” • Sex-linked- genes located on the sex chromosome. Usually on the “X” • Nondisjunction- A chromosome mishap in meiosis

A Karyotype is a photograph of the chromosomes of a single cell.

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Huntington’s Disease • Symptoms: Gradual Brain tissue loss in middle age. • Defect: Inhibitor of brain cell metabolism • Autosomal/somatic dominate • 1/10, 000

Cystic Fibrosis • Symptoms: Mucus clogs lungs, liver, pancreas • Defect: Failure of chloride ion transport mechanism • Autosomal recessive • 1/2080 whites most common disorder

Sickle Cell Anemia • Symptoms: impaired blood circulation, organ damage • Defect: Abnormal hemoglobin molecules – RBC’s • Autosomal Recessive • 1/500 African Americans -If heterozygous will not get malaria

Tay-Sachs Disease • Symtoms: deterioration of CNS in infancy. • Defect: Defective form of enzyme hexosaminidase A (Hex A) • Autosomal recessive • 1/1600 Jews of European desent

Phenylketonuria (PKU) • Symptoms: Failure of brain to develop in infancy; if untreated causes death. • Defect: defective form of enzyme phenylalanine hydroxylase • Autosomal recessive • 1/18, 000 urine test, treated by diet until puberty.

Hemophilia • Symptoms: failure of blood to clot • Defect: defective form of blood-clotting agent. • X-linked recessive • 1/7, 000

Muscular Dystrophy • Symptoms: wasting away of muscles; short life expectancy • Defect: muscle fiber degenerate • X-linked recessive • 1/10, 000 “Jerry’s Kids”

Down’s Syndrome • Symtoms: Mental retardation with abnormal physical features. • Defect: extra “X” chromosome • Non-disjunction of the 21 st pair of chromosomes • Somatic chromosome • Also called Trisomy 21

Klinefelter’s • Symptoms: only in males, sterile, do not develop 2 nd sex characteristics. Below normal intelligence • Defect: extra “X” in 23 pair of chromosomes • Meiosis error- genotype XXY

Turner’s • Symptoms: only in females, appear normal at birth, become stockier & shorter than other females- large necks, sex organs & breasts do not develop- sterile • Defect: missing “X” chromosome in 23 rd pair • Non-disjunction of sex chromosome • Genotype XO