Classifying Genetic Disorders

Autosomal Dominant

Autosomal Recessive

Sex-Linked Disorders

Chromosomal Abnormalities

Autosomes

Sex Chromosomes

Single Gene Chromosomal

Large portion or entire

chromosome

Human Genetic Disorders21 of the 3,000

• Cystic Fibrosis• Tay-Sachs • Albinism• Huntington Disease• Achondroplasia• Marfan Syndrome• Club Foot• Duchenne Muscular

Dystrophy• Down Syndrome• Cri-Du-Chat• Hemophilia• Sickle-Cell Anemia

• Klinefelter Syndrome• PKU• Diabetes• Adrenoleukodystrophy• Red-Green Colorblindness• Polydactyly• SCIDs• Progeria• Turner Syndrome

Cystic Fibrosis• Affects lungs and digestive system

• Eastern European ancestry

•1 in 25 are carriers of mutated gene

•Avg. lifespan = 32 years

•CTFR protein abnormality

Cystic Fibrosis

Tay - Sachs

Tay - Sachs

• Eastern European Jewish decent

• Lack vital enzyme (protein) Hex–A needed to break down fatty waste substance found in brain cells.

• No Hex A = abnormal accumulation of fatty waste in brain cells

• Lose motor skills and mental functions

• Eventually blind, deaf, mentally retarded, paralyzed and non responsive to environment

• Death by age 5

Albinism

• Altered gene does not allow body to make the usual amount of a pigment called melanin

• 1 in 17, 000 people

• Little or no pigment in

eyes, skin and hair.

Huntington Disease• Gene produces protein

called Huntington which leads to damage of the nerve cells in the brain.

• Slowly diminishes the affected individual's ability to walk, think, talk and reason. Jerky movements common.

• Late onset b/w 30-50 yrs.

• Death occurs approximately 12 years after onset.

• Crosses all races and ethnic backgrounds

Huntington Disease

Are there carriers in disorders that are autosomal dominant?

Achondroplasia• Genetic disorder of bone

growth that is evident at birth.

• Affects about one in every 25,000 births

• Occurs in all races and in both sexes.

• Normal torso , short arms and legs, generally the head is large, the forehead is prominent, and the nose is flat at the bridge.

Marfan Syndrome

Marfan Syndrome • A connective tissue disorder.

• Linked to the FBN1 gene, chromosome 15, which encodes a protein called fibrillin, essential for the formation of elastic fibers found in connective tissue.

• Without the structural support provided by fibrillin, ruptures in the walls of major arteries can occur, spine may curve, eye lens may dislocate.

• Unusually long limbs, and is believed to have affected Abraham Lincoln.

Club Foot

Duchenne Muscular Dystrophy

• Rapid progression of muscle degeneration that occurs early in life (first 3 yrs).

• An estimated 1 in 3500 males affected worldwide.

• Gene for DMD found on X Chromosome. Encodes protein called dystrophin which is involved in structural support of muscle cells

• Clumsiness in walking, many falls by age 10, muscles so weak wheelchair bound. Death by age 20

Down SyndromeTrisomy 21Trisomy 21

Some degree of mental retardation, or cognitive disability, developmental delays.

Common physical traits, but not always present: - folds over the eyes

- flattened bridge of nose

- a single palmar crease

Down Syndrome

Klinefelter Syndrome

• 47,XXY: Extra X chromosome

• Hormone Imbalance

• sterility, breast development, small testes, incomplete masculine body build, sparse facial and body hair

• Non-disjunction disorder

Klinefelter Syndrome

Cri-du-chat Syndrome

Caused by genetic material being lost from the short arm of the 5th chromosome

Dr Lejeune (French) discovered the disorder in 1963 gave the syndrome the name "cat cry" due to the characteristic cry of newborns which is not unlike the mewing of a kitten.

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Cri-du-chat Syndrome

Turner SyndromeXO

Turner Syndrome

Hemophilia

Deficiency in clotting factors that must work in a specific sequence to produce blood clotting. 

HemophiliaEuropean Royal Family

Sickle-Cell Anemia

• Most commonly found among African American population

• Carriers less likely to die from Malaria

• Sickle cell anemia is a painful disease caused by red blood cells that become malformed into bent and distorted shapes.

• “Sickled" cells don't have the ability to flex like the normal cells as they travel through the capillaries.

Sickle-Cell Anemia~256,000 base pairs in gene

Phenylketonuria (PKU)• Enzymatic disorder affects

the way the body processes protein

• Cannot process phenylalanine (amino acid) in protein

• Mental retardation and epilepsy occur if not detected early

• If treated early, lead normal life with diet modifications (low-protein)

Diabetes Mellitus• Serious, chronic condition of high blood sugar. Person has

an inability to transport sugar from the bloodstream into cells

• If left untreated, it may result in blindness, heart attacks, strokes, kidney failure and amputations.

• Diabetes is the fourth leading cause of death in the United States. More than 178,000 people die each year from this disease.

• 2 TypesType I – IDDM (pancreas does not make insulin)

Type II – NIDDM (pancreas makes little or not enough and body does not properly use the insuliln) – most common

Adrenoleukodystrophy (ADL)Lorenzo’s Oil

Born May 29, 1978, now 25 yrs. oldCannot see, talk or move Communicates by blinking

Adrenoleukodystrophy (ADL)

• (ALD) is a peroxisomal disorder.

• Peroxisomes are cell organelles involved in the metabolism of long chain fatty acids. One or more peroxisomal enzymes may malfunction causing accumulation of very long chain fatty acids.

• In the brain these fatty acid chains cause breakdown myelin which surrounds nerve cells

• Lorenzo’s Oil = mixture of olive and rapeseed oils that,

delay the build-up of the fatty acids thought to contribute to the breakdown of the nerve coating.

Red-Green Colorblindness

A person cannot distinguish shades of red and green (usually blue-green).

Occurs mostly in males

Polydactyly

Extra digit on hand or foot or both

1/1000 in Caucasian population; 1/100 in African American population

Sever Combined Immunodeficiency Disorder

(SCIDs)

Persons born with SCIDs lack the ability to fight off infections

Often called "bubble boy disease"

Progeria-Children with Progeria die of atherosclerosis (heart disease) at an average age of thirteen years

-There is some evidence that it is inherited from a parent on an autosome.  Some scientists believe that the genetic defect might arise through a spontaneous mutation.