Genetic Disorders & Testing Warning: sensitive material Polydactyl- dominant trait

review Results of a mutation? 2 types of mutations What is a mutation?   What is a mutation? 2 types of mutations Gene or Chromosomal

Review Types of Gene mutations 1. Point mutation: change in one nitrogen base in DNA; Ex. Substitution 2. Frameshift Mutation Ex. insertion or deletion of a base shifts entire sequence for translation

review Chromosomal Mutation Change in # or structure of the chromosome Mitosis & meiosis usually not passed on because zygote dies Ex. Deletion Inversion Duplication translocation

Nondisjunction occurs when a chromosome pair fails to separate properly during meiosis-can happen to any chromosome pair 2 types: 1. Monosomy: when gamete has one less chromosome than it should only 45 chromosomes (need 46) Ex: Turner syndrome- occurs only in females 2. Trisomy: when gamete has one more chromosome than it should 47 chromosomes( need 46) Ex: Down’s syndrome, extra #21 Don’t forget: you have 23 pairs(46 chromosomes) in each cell in your body

GENETIC DISORDERS THESE ARE THE ONES YOU NEED TO KNOW FOR THE TEST! Autosome- lst 22 pairs of chromosomes Sex-linked- 23rd pair

Autosomal Recessive Disorders Disorder: Progeria Facts: rapid aging disease, Caused by point mutation Symptoms: thin, bald, old-looking skin Incidence: rare (live to teens or maybe 30’s) Treatments: none

Autosomal Recessive Disorders Disorder: Albinism Facts: can be caused by a autosomal recessive, autosomal dominant or sex-linked trait; point mutation Symptoms: absence of pigment in hair, skin, eyes; defect of melanin production Photophobic- sunlight painful to eyes Incidence: common in European descent; less common in African Americans & Asians Treatments: none

Autosomal Recessive Disorders Disorder: PKU Facts: missing an enzyme that breaks down Phenyalanine (in milk) /it accumulates in the central nervous system Caused by a point mutation Symptoms: can cause mental retardation, abnormal growth patterns Incidence: rare in African Americans & Japanese; more common in Irish Treatments: test newborns- change diet

Autosomal Recessive Disorders Disorder: CF- Cystic Fibrosis Facts: mucus in lungs & digestive tract is very thick ; caused by point mutation Symptoms: makes breathing & digestion difficult Incidence: most common in Caucasians(whites) 1 in 2000 white; 1 in 25 carry recessive allele. Treatments: frequent lungs infections, daily therapy is needed to loosen & remove mucus

Autosomal Recessive Disorders Disorder: Tay-Sachs Facts: disorder of central nervous system: brain & spinal cord missing an enzyme which breaks down lipids; accumulates in brain Symptoms: everything goes in reverse; deteriorates Incidence: 1 in 27 Jews, Cajuns(Lousiana), & French-Canadians are carriers Treatments: none; happens within 1st year most children don’t live past 5

Autosomal Recessive Disorder/ Codominance Disorder: Sickle-Cell Anemia Facts: sickle-shaped blood cells block/clot up blood vessels; point mutation Symptoms: pain in joints, anemia, weakness Incidence: 1 in 375 African Americans Treatments: bone marrow transplants, medicines

Autosomal Dominant Disorders Disorder: Huntington’s Disease Facts: degeneration of nerve cells in the brain because of faulty gene on chromosome # 4(point mutation) Symptoms: mood swings, depression, memory loss, decline in movements & speech Death usually occurs 10-20 years after onset of symptoms. Symptoms begin between ages of 30-50. Incidence:Every child of a parent with the disorder has a 50% chance of inheriting Huntington's Disease. Treatments: none *Mother murdered/assisted suicide/ her sons in the nursing home here in Ga.

Autosomal Dominant Disorders Disorder: Achondroplasia Facts: stunted bone growth; type of Dwarfism Point mutations Symptoms: Torso is normal but arms and legs are short. Incidence: 1 out of 25000 Only heterozygotes have this disorder. Homozygous dominant condition results in death of the embryo. Treatments: none

Aneuploidy (caused by Nondisjunction) Disorder: Down’s Syndrome (Trisomy 21) Facts: most common reason for mental retardation; chromosomes failed to separate Symptoms: mental retardation, slanted eyes Incidence: 1 in 900; most cases not inherited Treatments: none

Aneuploidy (caused by Nondisjunction/ Trisomy) Disorder: Klinefelter Syndrome Facts: XXY - Trisomy- chromosomes failed to separate Symptoms: male, taller than average, longer limbs, sterile, may have some mental retardation Incidence: Treatments: none

Aneuploidy (caused byNondisjunction/ Monosomy) Disorder: Turner’s Syndrome Facts: female, only 1 X b/c of Nondisjunction Symptoms: sterile, lack of sexual development(no ovaries), short stature Incidence: Treatments: none

Chromosomal mutation Disorders Disorder: Cri Du Chat Syndrome Facts: missing piece of chromosome # 5 (deletion) Symptoms: mental retardation, high-pitched cry that sounds like a cat. Incidence: avg. 1 in 40, 000 Treatments: none

Sex-linked Disorders. write Xm Xm , XmY Sex-linked Disorders *write Xm Xm , XmY *most disorders are x-linked, recessive Disorder: Muscular Dystrophy (MD) (duchenne’s only) Facts: recessive, x-linked; many types of MD Symptoms: muscle loss & weakness Incidence: mainly in males; all ethnic groups have an equal chance of MD Treatments: physical therapy , braces, wheelchair

Sex-linked Disorders Disorder: Hemophilia Facts: recessive, x-linked; blood does not have clotting factors Symptoms: bleed excessively or to death Incidence: mainly in males ; Royal Family Treatments: inject themselves with purified clotting factors to prevent or stop bleeding

Sex-linked Disorders Disorder: Color-blindness Facts: recessive, x-linked disorder; Cones in eyes(color receptors) are absent or lack of pigment Symptoms: cannot tell difference between certain colors Incidence: mainly in males- passed from mother; red-green color blindness most common Seeing only black/white is rare Treatments: none

1. Karyotyping: pictures of chromosomes are matched up according to size 4 Methods of detection

methods of detection cont 2. Ultrasound: sound waves/ image. Used to detect abnormalities of limbs, organs, etc. 3. Amniocentesis: fluid surrounding the fetus is drawn out by needle, fetal cells collected/ grown Chromosomes karyotyped

4. Chorion villi sampling: a sample of the chorion (membrane surrounding fetus) is taken, chemical tests and karyotyping are performed